Free online calculators

Checks whether your bag meets carry-on luggage size rules for airlines.

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

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

Enter input, cached and output token counts to see cost per model from a price table.

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.

Shows how savings grow over time given a starting amount, regular deposits and an assumed yearly return, with yearly totals.

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

Animated support-desk model using Erlang C that shows waits exploding near full utilisation and how much an extra agent helps.

A basic calculator built as an installable offline-capable web app with React and Redux.

Czech income tax calculator for individuals (Czech language).

Web calculator for estimating and comparing LLM API costs across models.

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.

All-in-one site with 21 calculators and tools, including math, finance, graphing, conversion, password and QR.

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.

Small React app that computes loan EMI and monthly interest.

Calculates RC low-pass cutoff and draws Bode magnitude and phase plots, with an audio demo.

Divides rent among roommates fairly using each person's income and room.

Financial independence planner showing when savings can fund your spending.