Compound Interest Calculator
See how savings and investments grow with compound interest and monthly contributions.
Percentage Calculator
Three percentage calculations in one place.
Percentage formulas
X% of Y = (X ÷ 100) × Y. Percentage = (Part ÷ Whole) × 100. Percentage change = ((New − Old) ÷ |Old|) × 100.
Worked example
20% of 250 is 50. 50 is 25% of 200. Going from 80 to 100 is a 25% increase.
How to use this calculator
- Fill in whichever pair of boxes matches your question.
- Select Calculate — all three results are shown together.
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Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 20% of 250 = 0.20 × 250 = 50.
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value, and multiply by 100.