A and B are labeled clearly so you can calculate a percentage, a share of a whole, or a change rate without guessing.
Calculation type
Example: what percent is 30 of 120?
Formula
A (part) ÷ B (whole) × 100
Quick examples
Tap an example to fill the inputs.
Inputs
Example: what percent is 30 of 120?
A is
25%
30 is 25% of 120.
Remaining
75%
As decimal
0.25
As fraction
30 / 120
Visual ratio
A is usually the number you check first, and B is the whole or base. Each input explains whether it is a part, whole, old value, or new value.
For 30 out of 120, enter A=30 and B=120. A is the part, B is the whole.
Yes. Use A% of B for discounts, tax, tips, and fees.
Yes. Decimal ratios are scaled before being reduced.
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