Free online calculators

Web calculator with user-defined variables and functions, complex numbers, derivatives and integrals.

Notepad-style calculator where each line is evaluated live, with units, percentages and variables.

Web version of an arbitrary-precision calculator that understands units, currencies and conversions.

Calculator that works with ranges and uncertain numbers instead of exact values.

Collection of small calculators for everyday topics, with active calculator packs cached for offline use.

Shows how overpayments cut mortgage term and interest, charted with D3.

Computes UK capital gains from broker transaction exports and produces a PDF report for self assessment.

Calculates income tax for employees in Bangladesh.

Visual UK take-home pay breakdown covering income tax, NI, pension relief and salary sacrifice.

Prepares Polish PIT-38 tax figures for foreign stock trades from broker exports.

Crypto gain and loss tax calculator for trade histories.

Estimates taxes owed by Romanian PFA sole traders (Romanian language).

Calculates UK capital gains and dividend tax on investments, including corporate actions.

Polish B2B net income calculator comparing ryczalt, flat-tax and tax-scale options (Polish).

Computes Ghana take-home pay, income tax and SSNIT contribution from gross income.

Estimates how long a circuit runs on a chosen battery type from its capacity and the load.

Estimates the token cost of an image for OpenAI vision models from its width, height and detail level.

Czech income tax calculator for individuals (Czech language).

Simulates Warhammer 40,000 attack dice and shows hit, wound and save probabilities as charts.

Works out which trades rebalance a portfolio while limiting taxes.

Swiss income, wealth and capital tax estimator by municipality and marital status (German).

Converts between bits, bytes and larger data units.

Estimates return on investment from buying a home versus renting.

Estimates the savings goal and earliest age you can retire early.