CalcDex

TL;DR

CalcDex is one free program for Windows that does almost every kind of calculation in one place — like having a big box of hundreds of different calculators (for money, health, school maths, building jobs, cooking, sports, and much more) that all work with no internet, no ads, and no sign-up. Pick a calculator, type your numbers, read the answer with the working shown in plain words. It also works from the command line for people who like typing commands.

Free forever. Optional donations are allowed but never required and never unlock anything. No ads, no in-app purchases, no selling data.

Who it is for

CalcDex is built for students, teachers, professors, scientists and engineers — people who need a result they can check, not just a number. That is why every calculator:

• shows its formula, the substituted values, and the result (worked steps you can follow or mark against),
• keeps full precision in results (rounded forms are labelled, never silently substituted),
• accepts scientific notation inputs (e.g. 6.022e23, 1.5e-3),
• names the constants it uses (g = 9.80665 m/s², R = 0.082057 L·atm/(mol·K) = 8.314 J/(mol·K), Avogadro 6.02214076×10²³),
• uses correct units and symbols, and labels anything that is an approximation as an ESTIMATE (body-fat, BAC, race prediction, carbon footprint and similar),
• explains input errors in words that say why there is no answer (for example: log of a negative number has no real value).

For students & teachers: results read like worked solutions — formula first, then the numbers put in, then the answer — so homework and lab calculations can be verified line by line.

For professionals: the same registry runs from the command line, so any calculation in the window can be scripted, repeated and logged with identical output.

What it does

CalcDex brings together the calculator sets of two big websites — Omni Calculator (3,938 calculators) and Nutilz (637+ tools, calculator subset only) — as one offline desktop program. Where those sites list hundreds of near-identical pages (for example a separate page for every unit pair), CalcDex uses one calculator where you pick the units — see docs/COVERAGE.md for the honest mapping.

Categories: Math, Finance, Health, Physics, Chemistry, Construction, Conversion, Statistics, Date & Time, Everyday, Sports, Food, Ecology, Other.

Every calculator shows its formula and the steps in plain words, and handles bad input (dividing by zero, square root of a negative, and so on) with a clear message instead of crashing.

The look

Dark "Terminal" theme, exactly SEAN's Purgeon Terminal colours: near-black background #0c0c0c, panels #121212, phosphor-green accent #4ade80, Cascadia Mono type, sharp corners everywhere.

How to use it (window)

Since v0.2.0 the window uses the Design 3 layout SEAN picked from the eight research mockups (mode rail / centre work area / history rail — the pattern Microsoft's Calculator app uses):

1. Run CalcDex.exe.
2. Mode rail (far left): the categories are modes — ALL, MATH, FINANCE, HEALTH, and so on. Click a mode to see its calculators, or hold Alt and press the key printed on the mode's row. The full working shortcut set is Alt+1 … Alt+9, Alt+0 for the first ten modes, then Alt+Q, Alt+W, Alt+E, Alt+R, Alt+T for the last five, in rail order. The Search box at the top of the rail filters every calculator by name.
3. Centre: click a calculator in the chip strip under the mode heading, then fill in the labelled boxes (list calculators take numbers separated by commas or spaces in one big box). Dates go in ONE box per date, in the format the hint under the box shows — MM/DD/YYYY, so 04/23/1988 means April 23, 1988. Press the green Today? button beside any date box to fill in today's date (the Age calculator's End Date and the Countdown's From Date already start filled with today).
4. Press CALCULATE (or Enter). The result appears in the Display at the top of the centre in large green type, with the full formula and worked steps in the footer block underneath — nothing is cut down to one line.
5. History rail (right): every result is saved there at once (see Calculation log below). RE-OPEN on an entry restores its calculator and inputs. On a narrow window the rail collapses — below 1100 points wide the header LOG button shows the same history in the centre instead.

How to use it (command line)

Every calculator works the same from the command line — nothing is window-only:

CalcDex --list
CalcDex --search loan
CalcDex compound-interest 1000 5 10
CalcDex bmi 70 175
CalcDex mean 1 2 3 4
CalcDex convert-length 1 7 3
CalcDex age 04/23/1988 10/25/2026

Dates on the command line are one argument in MM/DD/YYYY form, just like the window (the old six-number form 1988 4 23 2026 10 25 still works and gives the identical answer).

More command-line tools (v0.3.0 — everything in the window has a command-line counterpart; see docs/PARITY.md for the full table):

CalcDex --describe bmi
CalcDex bmi --example
CalcDex compound-interest --vary 1 0 10 2.5 1000 10
CalcDex --batch compound-interest in.csv out.csv
CalcDex --sig-figs 3 compound-interest 1000 5 10
CalcDex --favourite bmi
CalcDex --favourites

More command-line tools (v0.4.0 — display formats, copy formats, expressions, typed quantities, spec check, help, log undo, update check):

CalcDex --format engineering compound-interest 1000 5 10
CalcDex --format auto compound-interest 1000 5 10
CalcDex bmi 70 175 --as csv
CalcDex bmi 70 175 --spec 18.5 25
CalcDex expr "2*(3+4)^2"
CalcDex bmi "154 lb" "5 ft 9 in"
CalcDex --help-guide
CalcDex --restore-log
CalcDex --check-update

Numbers go in the same order as the labelled boxes in the window. For unit converters the two extra numbers pick the units from the numbered list shown in that calculator's description. CalcDex --help explains the rest.

New in v0.8.0 — the engineers batch

Electronics and mechanical tools, a materials table, and a polished calculation log — in the window and on the command line alike. Registry now 316 calculators. This batch completes the 50-enhancement program (items 41–45 and 49).

• Electronics pack (#41, in Physics). Resistor Colour Code: type the band colours (red red brown gold) to read a resistor, or type a value (4700, 4.7k) to get its bands. Resistors in Series & Parallel gives both totals for one list. Voltage Divider gives Vout, the current, and each resistor's power.
• Tolerance Stack-Up (#42, in Construction). Dimensions as (nominal, tolerance) pairs → the total with its worst-case range and its RSS (root-sum-square) range.
• Safety Factor & Margin of Safety (#43). Strength against an applied stress (or a load over an area): FoS, MoS, and a plain-language reading — below 1 is called a predicted failure.
• Materials table (#44). Twelve common materials with typical density, resistivity and Young's modulus values, labelled as typical values (resistivity is marked not-applicable for insulators). CalcDex --materials prints the table; the header's MATERIALS view is the same table with a USE E IN BEAM button per row.
• Mechanical pack (#45, in Construction). Bolt Torque (T = K × D × F, N·m and ft·lbf) and Beam — Stress & Deflection (simply supported, central load, rectangle or circle section; E typed in or taken from a materials-table code).
• Log polish (#49). Search the log, filter it by calculator, tag or date, pin entries so the 500-entry trim never drops them, and export the filtered set to a text file: CalcDex --log-search, --log-filter, --log-pin, --log-export — and the same controls in the window's log view.

New in v0.7.0 — the scientists batch

Tools for lab and research work, in the window and on the command line alike. Registry now 309 calculators.

• Paste a column (#32). List calculators (Mean, Standard Deviation, Linear Regression and the rest) accept numbers separated by commas, spaces, tabs, semicolons or new lines — a copied spreadsheet column pastes straight in, in the window field and as command-line arguments. A token that is not a number is named in the error.
• Replicates Summary (#33). One step from a set of repeated measurements to the mean, sample standard deviation, standard error of the mean, and the 95% confidence interval (Student's t for small samples, the normal value beyond 30 degrees of freedom).
• Outlier Check (#36). Quartiles (Q1, median, Q3), the interquartile range, and the 1.5×IQR fences, with any outlying values listed — or a plain statement that there are none.
• Serial Dilution (#35). A dilution series planned step by step: starting concentration, then either transfer + diluent volumes or a plain factor per step, giving the concentration after every step.
• Constants library (#38). Fifteen CODATA 2018 constants (c, h, ħ, e, k_B, N_A, R, G, ε0, μ0, m_e, m_p, u, F, σ) usable by name in the Expression Calculator — h*c/500e-9 is the energy of a 500 nm photon. The CONSTANTS view lists them with an INSERT button; CalcDex --constants prints them. Your own constants (CalcDex --define name=value) are stored in the shared settings file and can never replace a built-in.
• Uncertainty propagation (#40). In the Expression Calculator, 10 ± 0.2 (or 10 +/- 0.2) carries its uncertainty through + − × ÷ ^ and functions by the first-order lab rules, and the result prints as value ± uncertainty with the percentage — each step names the rule used.
• Lab notebook (#39). Any log entry can carry a tag and a note (LOG view, or --log-tag / --log-note); edits back the log up first. --lab-export <file> writes the log as a plain text lab record, oldest first, with the timestamps stated as UTC. History files from earlier versions read unchanged.

New in v0.6.0 — the teachers batch

Tools for the front of the classroom, in the window and on the command line alike:

• Projection mode — a header toggle rendering the window at about 1.5x with higher contrast, saved between runs (CalcDex --projection on|off).
• Problem sets — build a set of problems (calculator + values) in the SETS view or with CalcDex set new|add|open; the plain-text set file holds problems only, so it doubles as the student assignment. Sets can be generated from a seed (set generate --seed N --count K) — the same seed always makes the identical set.
• Worksheets and answer keys — export a printable plain-text worksheet (name/date header, working space, no answers) and a separate teacher answer key with answers and one-line working.
• Bulk marking — CalcDex --mark <set> <answers.csv> marks a whole class CSV (fractions checked exactly) and prints a score line per student.
• Course packs — the rail filters the calculators to GCSE (115), A-Level (161), AP (121) or Undergrad (210) by real curriculum fit (CalcDex --pack GCSE --list).
• Demonstration mode — DEMO hides a run's result values until REVEAL is pressed; the log keeps the real results.
• Formula sheets and class examples — printable per-category formula sheets (--formula-sheet Math out.txt) and a saved examples library (--save-example, --examples, --open-example).

New in v0.5.0 — the students batch

Tools for learning and teaching, in the window and on the command line alike:

• Formula & symbols (#19). Every calculator shows its formula and what each symbol means, in a FORMULA & SYMBOLS section under its form. CalcDex --describe <id> prints them too.
• Deeper steps (#12). The STEPS header selector's Deeper mode shows the formula, the formula with your values in it, the working, and the result, as four labelled stages. Command line: --steps deeper.
• Check my answer (#13). Type your own answer and be checked: exactly for the fraction calculators, within 0.5% for the rest. A wrong answer that matches a common slip (100x, 4x, squared, sign flipped, ...) names the likely slip. Command line: CalcDex <id> <args> --check <answer>.
• Exact mode (#14). A display format alongside Off / Sig figs / Decimals / Engineering / Auto: fraction results are labelled exact, pi geometry also shows its exact form (25*pi), and the Expression Calculator works rational expressions out exactly (1/3 + 1/6 = 1/2). Anything outside that scope keeps the decimal answer and says so. Command line: --format exact.
• Practice mode (#15). The PRACTICE header toggle opens a view that generates problems (answer hidden) for the picked calculator or a random one, checks your answer, and can reveal the worked solution. A seed field makes problem sequences reproducible. Date, list, unit-code and lookup-table calculators are excluded — the view says so. Command line: CalcDex <id> --practice --seed N [--answer X].
• Graph plot (#17). The Expression Calculator plots its expression in x (range fields included); the quadratic solver plots its parabola. Command line: CalcDex expr "x^2" --plot -5 5 prints the plot as CSV sample points.
• Export worked solution (#18). EXPORT SOLUTION under the steps saves the name, formula, inputs, steps and result as a plain-text file. Command line: CalcDex <id> <args> --export <path>.

New in v0.4.0 — the rigour batch

Program items 2, 3, 4, 5, 6, 7, 8, 9, 10 and 37, plus four standing-rule features. Registry now 306 calculators. Everything is in the window AND on the command line:

• One display-format setting. The header FORMAT selector (Off / Sig figs / Decimals / Engineering / Auto) replaces the v0.3.0 SIG FIGS selector. Decimals shows a fixed number of decimal places; Engineering shows the headline with SI prefixes (1.63 k, 4.2 M, 350 m, down to pico); Auto works out the significant figures from the numbers you typed and says why ("Inputs carry 3 significant figures"). Only one annotation line is ever added, a VIEW row under the display re-renders the current result in another format without changing the setting, and a Rounding choice (Half up / Banker's / Truncate) controls how halves round inside every format. All of it is display only — full precision is always kept and logged. CLI: --format <mode[:n]>, --decimals N, --rounding half-up|bankers|truncate.
• Copy the result four ways. Buttons under the display copy the result as plain text, LaTeX (the printed values and lines with the text escaped and numbers in $...$ — an export of what CalcDex printed, not a re-derived formula), scientific notation, or CSV (label,value rows). CLI: --as latex|csv|sci|plain.
• Expression Calculator. A new Math calculator that takes a whole expression — 2*(3+4)^2, sin(30), sqrt(16)+abs(-3) — with + − * / ^, parentheses, the functions sin cos tan asin acos atan sqrt ln log10 exp abs, constants pi/e/tau and a degrees/radians switch. Mistakes get teaching errors (where in the expression, and what was expected). Every run is saved in the calculation log, which is its paper tape. CLI: CalcDex expr "2*(3+4)^2".
• Typed quantities. Fields that carry a unit family accept amounts typed the way people write them: 5 ft 3 in, 1.2 kg, 70 F, 2 h 30 min, 3 lb 4 oz. Compound amounts add up and are converted into the unit the field expects (converters: into the FROM unit you picked). Coverage: all converter calculators, the physics set (speed, force, energy, power, pressure, Ohm's law, projectile, pendulum, wave, torque, momentum and more) and the BMI/BMR/water/ protein health calculators. Other fields keep plain-number entry. If a typed amount's dimension does not match the field — a length typed into a mass field — the run stops with a plain warning naming both. Plain numbers never warn.
• Five compound-unit converters. Density, Fuel Consumption (L/100km ↔ mpg US/UK ↔ km/L), Data Rate (Mbps ↔ MB/s and more), Concentration (mg/mL ↔ g/L ↔ % w/v) and Energy Density — in the Conversion category, with examples, hints and known-answer checks like the other converters.
• Spec check. Enter Min/Max under the display and each numeric result line is judged PASS (inside the limits — the limits themselves count as inside) or FAIL, saying which limit and by how much, with a ✓/✗ symbol and a word as well as colour. CLI: --spec MIN MAX.
• Built-in help. The header HELP button (or F1) opens a plain-words guide inside the program — what CalcDex is, the five things people do most, the keyboard shortcuts, where the files live, and the command line in 3 lines. CalcDex --help-guide prints the same text.
• Undo for clearing the log. CLEAR LOG saves the log to history-backup.txt first; RESTORE CLEARED LOG in the history view (or --restore-log) puts it back. Batch runs refuse to overwrite an existing output file unless you allow it (OVERWRITE toggle in the window, --force on the CLI) — and then the old file is kept as a .bak copy.
• Drag and drop. Drop a .csv file on the window and the BATCH panel opens with the input path filled in.

New in v0.3.0 — Batch 1 of the 50-enhancement program

Ten enhancements (program items 1, 11, 16, 20, 31, 34, 46, 47, 48, 50), every one of them in the window AND on the command line:

• Significant-figures mode (1). The header's SIG FIGS selector (Off / 2 / 3 / 4 / 5 / 6) adds a rounded showing of the result headline next to the full-precision answer — counted correctly (0.00456 to 3 figures stays 0.00456; 1628.89 becomes 1.63e3, so the count is never ambiguous). Display only: the stored result and the log always keep full precision. CLI: --sig-figs 3.

• Try an example (11). Every calculator has a TRY AN EXAMPLE button that fills in a worked teaching example and runs it at once. CLI: CalcDex bmi --example.

• Vary one input (16). The VARY section under the form sweeps one input across start/end/step and tables the results (200-row cap, stated in the panel). CLI: CalcDex compound-interest --vary 1 0 10 2.5 1000 10 (the field is numbered from 0, as in --describe; the remaining numbers are the other inputs in order).

• Hints under every input (20). Every field shows what format and unit it wants — and what the codes mean where a field takes codes (sex codes, unit numbers, activity factors). CLI: CalcDex --describe bmi prints them too.

• Batch from CSV (31). The header BATCH panel (or CalcDex --batch <id> <input.csv> <output.csv>) runs one calculator over a whole file. The header row names the fields in order — for Compound Interest that is:

  Principal P,Annual rate %,Years
  1000,5,10
  2000,10,5
  

  Each output row is the inputs plus the result headline, or ERROR: ... — one bad row never stops the batch. (In the window the file paths are typed: this toolkit has no file-picker dialog.) For list calculators the header is the single list label and each row's cells are the list values.

• Linear Regression & Calibration (34). A new Statistics calculator: enter (x, y) pairs and get slope, intercept, r, R², means, residuals, and the working (n, Σx, Σy, Σxy, Σx²). Add one extra value at the end — a measured y — and it predicts the x that produced it, x = (y − b) / m. Registry now 300 calculators.

• Favourites + Recent (46). The ★ FAVOURITE button on any calculator stars it into the FAVOURITES mode at the top of the rail (Alt+F), which also shows your last 8 calculators as Recent chips. CLI: --favourite bmi, --unfavourite bmi, --favourites.

• Ctrl+K quick search with synonyms (47). Ctrl+K (or /) jumps to search from anywhere; search understands everyday words — "home loan" finds the mortgage calculator, "bmi" finds Body Mass Index — and ranks exact names first. 40+ synonym pairs.

• Remembered inputs (48). Reopening a calculator restores the values you last used in it; RESET puts the smart defaults back.

• Smart defaults (50). Every field opens on a realistic, visible, editable default (the teaching examples double as the defaults): today in date fields, standard temperature/pressure in the gas laws (273.15 K, 1 atm, 22.414 L), g = 9.80665 m/s² inside the physics formulas, sane 0%/100% bounds elsewhere. The notable ones are listed in docs/AUDIT.md.

Tooltips: every button, toggle, field and key in the window has a plain-words tooltip saying what it does — no exceptions (enforced by construction in the code and checked by a test).

Settings file: favourites, recent, remembered inputs and the display-format choice live in data\settings.txt beside the program (plain text, format documented in the file's code). On the first run of v0.9.0 or later, a settings file in the old %APPDATA%\CalcDex folder is copied into data\ automatically; the original is left untouched as the backup of the move. The window and the command line read and write the SAME file — it is the shared source of truth, so a calculator you star or run on the command line is starred and remembered in the window too.

Calculation log

Every successful calculation is saved automatically — whether you ran it in the window or on the command line — so classwork, lab results and estimates (SEAN's original request was for age calculations) can be found again later:

• The saved entries live in the History rail docked on the right of the window, newest first (header LOG shows/hides it; on narrow windows the same history opens in the centre). RE-OPEN on an entry loads that calculator with its inputs restored; CLEAR LOG empties the log — but first saves it to history-backup.txt, and RESTORE CLEARED LOG (shown when a backup exists) undoes the clear.
• Or from the command line: CalcDex --log prints the log, CalcDex --clear-log empties it (with the same backup) and CalcDex --restore-log undoes the clear.
• Entries are kept in data\history.txt beside the program (plain text: time, calculator, inputs — dates in MM/DD/YYYY form — and result). Only the newest 500 entries are kept; log timestamps are UTC. Failed calculations are never logged.

Privacy & network

CalcDex works fully offline and collects nothing. It makes no network connection at all unless you press Check for updates in the HELP panel (or run CalcDex --check-update), or switch on "Check for updates at startup" in the HELP panel (default OFF). The check only reads the newest release version from github.com and shows you the release page if it is newer — it never downloads or installs anything by itself.

Requirements & building

• Windows 10/11 for the shipped program (it is a standard Windows .exe; it also builds and runs on Linux for development).
• To build from source: a recent Rust toolchain, then: cargo build --release — and the full check is cargo fmt + cargo clippy --all-targets + cargo test --locked.

Install

Every release ships one 64-bit (x64) build in two forms, plus a checksum file:

• CalcDex-v{version}-x64-Setup.exe — the installer (per-user, no admin; installs to %LOCALAPPDATA%\Programs\CalcDex).
• CalcDex-v{version}-x64-Portable.zip — the portable build: the .exe, this README, the license and a short note. Unzip anywhere and run; the program keeps its files in a data folder beside the .exe.
• SHA256SUMS.txt — the SHA-256 of both downloads; check your copy against it before running.

The program is unsigned (no code-signing certificate) — Windows may warn on first run; choose "More info", then "Run anyway", if you trust this build.

Screenshots

Real captures from SEAN's machine, taken during the v0.1.1 field test (2026-10-25). They show the OLD left column — v0.1.2 makes the lists brighter, larger, and single-line; a fresh main-window capture after the readability fix is still needed.

Age Calculator (v0.1.1 capture): one MM/DD/YYYY box per date, the format hint under each field, and a Today? button beside each date. The result shown — 06/04/1977 to 10/26/2026 = 49 years / 18,041 days / 2,577 weeks — was independently re-checked and is exactly right.

Calculation Log (v0.1.1 capture): every calculation is saved automatically; RE-OPEN restores an entry's calculator and inputs, CLEAR LOG empties the log. Timestamps are UTC.

Captures still needed (real ones only, no placeholders): a fresh main-window shot of v0.4.0 showing the Design 3 layout with the rigour features (mode rail, display with its format/copy/spec rows, history rail, hints under the fields), ideally one at full width and one narrow enough that the history rail has collapsed.

Limitations (honest)

• Formula calculators only: the very specialised Omni pages that need live data (currency exchange rates, weather, stock prices), big lookup tables (tax brackets by country/year), medical diagnosis, or drawing graphs are not in v0.1 — they are listed in docs/ROADMAP.md, not silently dropped.
• Health and building results are estimates from the standard published formulas named in each calculator. They are not medical or engineering advice.
• See docs/PARITY.md for category-by-category scoring from test evidence.

License

MIT — see LICENSE. Free software; use it, share it, change it.