How do I calculate percentage increase?

Subtract the old value from the new, divide by the old value, then multiply by 100.

How do I reverse a percentage?

If a price increased by 20% to $120, the original was $120 ÷ 1.20 = $100.

Percentage Formula on CalcAll — free educational content with detailed examples.

How do I calculate percentage increase?: Subtract the old value from the new, divide by the old value, then multiply by 100.
How do I reverse a percentage?: If a price increased by 20% to $120, the original was $120 ÷ 1.20 = $100.