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Everyday Calculators & Converters

Quick everyday calculators for percentages, discounts, tips, dates and unit conversions. Instant answers with the working shown, so you can check them.

Maths

Percentages, discounts, increases and decreases with the working shown. Type two numbers and see every common percentage answer at once, with the formula behind each one.

  • Percentage Calculator

    Find X% of a number, what percent one number is of another, and the percent increase or decrease between two values, all at once with worked examples.

Small sums, done right

Most of the maths in daily life is simple until you need it in a hurry: working out a discount at the till, splitting a bill, checking how much a price really went up or converting a recipe from cups to grams. These calculators give you the answer immediately and show the working underneath, so you can see why it is right and do it yourself next time.

Built for speed

  • Answers as you type. There is no submit button. Results update the moment you change a number.
  • Several answers at once. Where it helps, a tool shows related results together. For example, the percentage calculator shows “percent of”, “what percent” and “percent change” from the same two numbers.
  • Works on any device. Every tool is designed for phones first, with large touch targets and number keyboards on mobile.
  • No sign-up, no tracking of your inputs. Everything runs in your browser.

Common mistakes these tools help you avoid

  • Mixing up percent and percentage points. A rate moving from 4% to 5% has risen by one percentage point but by 25 percent.
  • Assuming a rise and fall cancel out. A 20% increase followed by a 20% decrease leaves you 4% below where you started.
  • Rounding too early. Our tools keep full precision internally and round only the final result.

Each page explains the formula with real examples, so the tools double as quick refreshers on the maths itself.

Quick checks you can do in your head

A few shortcuts make it easy to sanity-check any result: 10% is the number with the decimal point moved one place left, 5% is half of that, and 1% is the decimal moved two places. Combine them to estimate tips, discounts and price rises before you reach for a calculator, then use the tools here for the exact figure.