How Percentage Calculator works

Solve percent-of, what-percent, percentage-change and increase or decrease calculations.

The formula

Percent of = percent × value. Percentage change = (new − old) ÷ |old| × 100.

A practical example

20% of 500 is 100; increasing 500 by 20% gives 600.

Important limitations

Results are estimates based only on the values you enter. They do not include every fee, tax, timing difference, market movement or product rule.

Frequently asked questions

Why can’t percentage change start at zero?

The formula divides by the starting value, so a zero start is undefined.

Can values be negative?

Yes where the calculation is mathematically defined.

Is percent change symmetric?

No. A rise and fall by the same percentage do not cancel.