How to calculate percentage
Percentage of base = P ÷ 100 × base Part as percentage = part ÷ base × 100 Percentage change = (new − original) ÷ |original| × 100
Worked example. 20% of 850 is: 170.
Example inputs — Calculate: Percentage of a number; Percentage: 20%; Base amount: 850. Starting values are illustrative.
From George Guju, founder of Calculyn · Educational calculator guidance, not professional advice.
Common questions answered
What is 10% of 50?What is 10% of 80?What is 10% of 100?What is 10% of 200?What is 10% of 500?What is 10% of 1000?What is 15% of 50?What is 15% of 80?What is 15% of 100?What is 15% of 200?What is 15% of 500?What is 15% of 1000?What is 20% of 50?What is 20% of 80?What is 20% of 100?What is 20% of 200?What is 20% of 500?What is 20% of 1000?
All percentage of a number answers →How it works
Choose a percentage of a number, a part-to-whole percentage, or a change from an original value. Change is measured against the absolute size of the original value; a zero base cannot define a percentage ratio.
Assumptions & limitations
- Results are rounded for display.
Formula and assumptions reviewed October 2026 by the Calculyn team. How we build our calculators
Frequently asked questions
How do I calculate a discount?
Use the 'Number − %' line. A 25% discount on $80 leaves $60.