Quick answers for everyday questions
These calculators handle the small sums that come up every day and are easy to get slightly wrong in your head.
Shopping and eating out. The percentage calculator covers the five most common percentage questions on one page. The discount calculator handles stacked discounts correctly — 30% off followed by another 20% off is a 44% discount, not 50% — and the tip calculator splits a bill fairly down to the cent.
Dates and time. The age calculator gives an exact age in years, months and days, while the date difference calculator counts the days or business days between two dates and can add or subtract periods from any date.
Measurements and travel. The unit converter covers length, weight, temperature, volume, speed, data and more. Planning a drive? The fuel cost calculator estimates the cost of a trip in miles or kilometres.
Health and rest. The BMI calculator is a quick screening tool, and the sleep calculator suggests bedtimes based on sleep cycles. Both are for general information only — they are not medical advice, and a healthcare professional can give you guidance for your own situation.
Why use these instead of a phone calculator?
Each tool shows the formula it uses and a worked example, so you can see why the answer is what it is. Results update as you type, and nothing you enter leaves your device.