∑ Calculivo

Percentage Calculator

Five percentage modes in one: of, what-percent, increase, decrease and change.

Result —

About this calculator

Most everyday percentage questions reduce to one of five forms. A good percentage calculator handles all of them without you having to remember which formula goes where. Pick the mode, type two numbers, and the result is ready instantly.

How it works

‘A% of B’ is the most common form — useful for tips, discounts, taxes and probabilities. It’s simply A divided by 100 times B.

‘A is what % of B’ inverts the question and tells you what share A represents of B. Use it to express scores, market share, or test results as a percentage.

‘Increase / decrease by B%’ applies a percentage change to A. Useful for price markups, discount calculations and tax adjustments.

‘Change between two values’ tells you how much A grew or shrank to reach B as a percentage. It’s the same math you use to express year-on-year growth — and remember it can be negative when B is smaller than A.

Formula

of:            (A / 100) × B
what-percent: (A / B) × 100
increase:     A + (A × B / 100)
decrease:     A − (A × B / 100)
change:       ((B − A) / |A|) × 100

Examples

20% of 250

Twenty percent of 250 is 50 — useful for tax, tip and discount calculations.

Result: 50

Year-on-year growth from 1,000 to 1,250

Growing from 1,000 to 1,250 is a 25% increase — the change as a percentage of the starting value.

Result: +25%

Frequently asked questions

Why are there five different modes? +
Because ‘percentage’ doesn’t describe one operation — it describes a family of related operations. Each mode covers the most common form of one of those questions.
What’s the difference between increase-by-B% and the new total? +
Increase-by-B% gives you the new total: original + percentage of original. If you want just the size of the increase, multiply A by B / 100.
Can percent change be negative? +
Yes — if B is smaller than A, the change is negative. It expresses a decrease as a percent of the starting value.
Is there a difference between percentage and percentage point? +
Yes. Going from 20% to 25% is an increase of 5 percentage points but a 25% increase as a relative change. The calculator’s ‘change’ mode reports the relative change.
Does it round? +
Results are shown to two decimal places. Internally the math is full-precision floating point.

Related calculators