Free Online Calculators with Clear Formulas

177 calculators and converters across health, finance, math, everyday life, construction and units. Every result shows how it was worked out.

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Health calculators

Body measures, nutrition, pregnancy and fitness tools, each with its formula and its limits.

Financial calculators

Loans, mortgages, savings, investing, business and tax calculators with assumptions you can change.

Math calculators

Arithmetic, algebra, geometry, probability and statistics tools that show their working.

Everyday calculators

Dates, time, school, travel and tech tools for daily life.

Construction & Science calculators

Materials, electrical and weather calculators with editable assumptions.

Converters calculators

Length, weight, temperature, area, data and regional units, using exact definitions.

Why use Adzita calculators

Formula shown beside every result, with a worked example generated by the same code, so the example always matches the tool.
Limits stated plainly. We say what each number cannot tell you.
Private by design. Calculations run in your browser and nothing you enter is stored or sent.
Fast and light. No account, no pop-ups, no third-party scripts.
Practical next steps on every page, not only a number.

Medical disclaimer: This tool is for education and general planning. It is not medical advice and does not diagnose any condition. If you are pregnant, under 18, have an eating-disorder history or a medical condition, speak to a doctor or registered dietitian before changing your diet or exercise.