Everyday calculators
Quick answers for the sums that come up every week: percentages, sale prices, restaurant bills and exact age in years, months and days.
- Percentage Calculator Work out a percentage of a number, find what percent one value is of another, or measure the percentage chang...
- Age Calculator Pick a date of birth and, if you like, a different date to measure to. The calculator returns exact age in ye...
- Discount Calculator Enter the original price and the percentage off. Add a second discount if the store stacks offers, and sales...
- Tip Calculator Enter the bill, choose a tip percentage and say how many people are sharing. The calculator shows the tip, th...
Everyday sums, done right
The percentage calculator handles three common questions: a percentage of a number, what percent one number is of another, and percentage change. Before you buy, the discount calculator shows the final price after one or two discounts and tax. When you split a bill, the tip calculator works out the tip and each person's share. The age calculator gives an exact age between any two dates.
Two mistakes these calculators help you avoid
Stacked discounts do not add up. A 20% discount followed by 10% saves 28%, not 30%, because the second discount applies to the already reduced price.
Percentage change is not symmetric. A price that falls from 100 to 50 dropped by 50%, but it must rise by 100% to recover.
Frequently asked questions
How do I calculate a discount?
Multiply the price by one minus the discount as a decimal. A 20% discount on 80 is 80 times 0.80, which equals 64.
How is exact age calculated?
The age calculator subtracts the birth date from the target date and returns the result in years, months and days.
Are these calculators free to use?
Yes. There is no sign-up and no limit on use.