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86 calculators · 14 categories · 3 languages · free, forever

Free calculators for everything you need to work out

Finance, health, dates, conversions, maths. Get an exact answer in seconds, with the formula and every step of the calculation. No sign-up, nothing to install.

Popular right now Mortgage Loan Compound interest Retirement Savings BMI

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Finance

Loans, savings, interest, investing and tax

23 calculators

Health

BMI, calories, metabolism and pregnancy dates

9 calculators

Mathematics

Percentages, fractions, equations and numbers

27 calculators

Date and time

Age, durations, deadlines and hours worked

2 calculators

Unit conversion

Length, weight, volume, temperature, energy and more

3 calculators

Geometry

Areas, volumes, perimeters and triangles

3 calculators

Physics

Speed, force, energy and electricity

3 calculators

Statistics

Averages, standard deviation, probability and counting

1 calculator

Construction

Concrete, paint, materials and surfaces

6 calculators

Everyday life

Tips, discounts, fuel and splitting the bill

3 calculators

Chemistry

Molar mass, dilutions and pH

3 calculators

Telecom & networks

IP subnetting, RF link budget and fiber loss

3 calculators

Medicine

Renal function, body surface area and due dates

3 calculators

Pharmacy

Dosing, infusion rates and dilutions

3 calculators

Popular calculators

Finance Mortgage Work out a mortgage payment, the total interest and the full amortisation schedule, with extra payments and taxes included. Finance Loan Work out the payment, total interest and real annual rate of a personal or car loan, fees and extra payments included. Finance Compound interest See what an investment grows to with compound interest, with or without regular contributions, at any compounding frequency. Finance Retirement Estimate how much you need for retirement, what your current savings will grow to, how much to save monthly, or how long your savings will last. Finance Savings Project what your savings will grow to, work out the deposit a goal needs, or find how long that goal will take. Health BMI Work out your body mass index, the WHO category it falls in, and the weight range that matches a healthy BMI for your height. Health Calories Estimate how many calories you burn in a day and the daily target for losing, holding or gaining weight. Mathematics Percentage Work out a percentage of a number, a share, a percentage change, or add and subtract a percentage — with every step shown.

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  1. 01

    Find the calculator

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  2. 02

    Enter your numbers

    Every field states its unit and its limits. The result updates as you type — there is nothing to submit and no account to create.

  3. 03

    Understand the answer

    Each result comes with the formula, the steps and the assumptions used. Copy the numbers, download a schedule, or share the exact calculation by link.

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Health CANRISK Finance Retirement Finance Deferred payment loan Finance Auto loan Finance Payoff time Finance Interest rate finder

Frequently asked questions

Is 1plus1 really free?

Yes. Every calculator is free to use, with no account, no trial and no paywall. The site is funded by advertising placed outside the calculation area.

Do you store what I calculate?

No. Calculations run entirely in your browser and are never sent to a server. Your inputs stay on your device; only your language and currency preferences are saved locally.

How accurate are the results?

Formulas come from published, citable sources and are covered by automated tests against known reference values. Each calculator lists the assumptions it makes, because most disagreements between two calculators come from different assumptions rather than different arithmetic.

Can I use the results for an official purpose?

They are estimates for information. Financial, tax and health figures depend on rules that vary by country and on personal circumstances the calculator does not know. Use them to understand and compare, then confirm with a professional or an official source.

Which languages is the site available in?

English, French and Spanish. Every calculator is fully translated — the text, the formulas, the examples and the questions — not machine-translated on the fly. You can switch language at any time from the header.