Forward percentages start with a base and find a part. Reverse percentages start with a total after a percent was applied and work backward to the original.
Reverse percentage formula
If the final amount includes a percent added on:
Original = Final ÷ (1 + rate/100)
If the final amount is after a discount:
Original = Final ÷ (1 − rate/100)
Sale example
You paid $60 after 25% off. Original ≈ $60 ÷ 0.75 = $80.
Using our percentage calculator
For simple “X% of Y” problems, enter the base value and rate directly. For reverse problems, solve with the formula above or try values until the forward calculation matches your known total.