Percentages Explained: Discounts, Tips and Pay Rises
Use percentages for discounts, tips, pay rises, price changes, and everyday comparisons with examples.
Open Percentage CalculatorPercentages are comparisons out of 100
A percentage expresses a number as a share of 100. That makes it useful for discounts, tips, interest rates, pay rises, price changes, exam marks, and comparisons. The three everyday questions are: what is X% of Y, X is what percentage of Y, and what is the percentage change from X to Y.
Use the AtlasPeak Percentage Calculator to switch between those three modes. It is useful for quick discounts in shops, pay rise checks, tip estimates, and comparing old and new prices.
Discounts and sale prices
To calculate a discount, find the percentage of the original price, then subtract it. If a jacket is 80 and discounted by 25%, the discount is 20 and the sale price is 60. For 10%, move the decimal one place. For 20%, double the 10% amount. For 5%, halve the 10% amount.
Percentage discounts can be misleading when the original price was inflated. Compare the final price with what you would normally pay, not just the size of the discount.
Tips and service charges
A tip is another X% of Y calculation. A 10% tip on 42 is 4.20. A 12.5% service charge is one eighth of the bill, so on 80 it is 10. When splitting a meal, calculate the final total after service charge, then divide fairly between diners.
If service is already included, adding another tip is optional. Check the receipt before calculating a percentage manually.
Pay rises and percentage change
A pay rise is a percentage change from old pay to new pay. Subtract old pay from new pay, divide by old pay, then multiply by 100. If salary rises from 30,000 to 31,500, the increase is 1,500. Divide by 30,000 and multiply by 100 to get 5%.
For real-world budgeting, also consider inflation and tax. A 5% gross pay rise does not mean take-home pay rises by 5%, because income tax, National Insurance, pensions, and deductions may change.
Avoid common percentage mistakes
A 50% fall followed by a 50% rise does not get you back to where you started. If something falls from 100 to 50, a 50% rise from 50 only takes it to 75. Percentage changes depend on the starting value.
Use the Percentage Calculator whenever the starting point changes or when a quick mental shortcut feels uncertain. It keeps the calculation simple and reduces mistakes in everyday decisions.
FAQ
How do you calculate 20% off a price?
Find 20% of the original price, then subtract it. For 80 with 20% off, the discount is 16 and the new price is 64.
How do you calculate a percentage pay rise?
Subtract the old pay from the new pay, divide by the old pay, then multiply by 100.
What is percentage change?
Percentage change shows how much a value rose or fell compared with the starting value.
Try the calculator
Put the guide into practice with the Percentage Calculator and check your own numbers.
Use Percentage Calculator