Use the four tools below to compare a starting value with a lower value, apply a percentage decrease, work backwards to the original amount, or measure the absolute change.
Percentage Decrease Calculator
Percentage decrease between two values
Value after a percentage decrease
Original value before a percentage decrease
Difference between two values
Which calculator should I use?
- Use Calculator 1 when you know the starting and final values.
- Use Calculator 2 to reduce a value by a known percentage.
- Use Calculator 3 to recover the original value from the final value and decrease rate.
- Use Calculator 4 to find the signed difference between two values.
Percentage decrease formulas
| result | Formula |
|---|---|
| Decrease | % = 100 × (Vi − Vf) ÷ Vi |
| Final value | Vf = Vi × (1 − % ÷ 100) |
| Original value | Vi = Vf ÷ (1 − % ÷ 100) |
Frequently asked questions about percentage decrease
How do I calculate percentage decrease?
Subtract the final value from the starting value, divide by the starting value and multiply by 100.
How do I find the value after a decrease?
Multiply the starting value by 1 minus the percentage written as a decimal. A 20% decrease uses a factor of 0.80.
How do I recover the original value?
Divide the final value by 1 minus the decrease rate. If 140 is the value after a 30% decrease, the original value was 200.
Is percentage decrease the same as a discount?
The calculation is the same. Discount is the usual shopping term; percentage decrease applies to prices, measurements, budgets and many other quantities.
Do two 50% decreases make a 100% decrease?
No. The second 50% is applied to the already reduced value. Starting from 100, the result is 25, an overall decrease of 75%.
Everyday examples
| Situation | Starting value | Decrease | Final value |
|---|---|---|---|
| Product discount | 1,200 | 15% | 1,020 |
| Fuel price drop | 6.50 | 8% | 5.98 |
| Weight reduction | 90 kg | 10% | 81 kg |
| Budget cut | 50,000 | 25% | 37,500 |
| Temperature drop | 40 °C | 20% | 32 °C |
See also…
