Percentage Increase / Decrease
Find the percent change between two values, or increase / decrease a number by a given percentage.
How to calculate percentage increase and decrease
To measure the percentage change between two numbers, take the difference between them, divide by the original value, and multiply by 100. The formula is % Change = ((New − Original) ÷ |Original|) × 100. A positive result is a percentage increase; a negative result is a percentage decrease. Here are four worked examples.
Difference is 100 − 80 = 20. Divide by the original and multiply: (20 ÷ 80) × 100 = 25% increase.
Difference is 750 − 1000 = −250. (−250 ÷ 1000) × 100 = −25%, a 25% decrease.
Change = 5000 × (15 ÷ 100) = 750. New value = 5000 + 750 = 5750.
Change = 1200 × (30 ÷ 100) = 360. New value = 1200 − 360 = 840.
Increase vs decrease — how the formula works
The sign of the result tells you the direction. When the new value is larger than the original you get a positive number (an increase); when it is smaller you get a negative number (a decrease). Always divide by the original value, never the new one — that is the most common mistake people make.
Quick percentage-change reference
A handy table showing what a few common percentage increases and decreases do to a value of 1000. Use it to sanity-check your own calculations.
| Increase | 1000 becomes |
|---|---|
| +5% | 1050 |
| +10% | 1100 |
| +25% | 1250 |
| +50% | 1500 |
| +100% | 2000 |
| Decrease | 1000 becomes |
|---|---|
| −5% | 950 |
| −10% | 900 |
| −25% | 750 |
| −50% | 500 |
| −100% | 0 |
Common uses in India
If your salary rose from ₹50,000 to ₹58,000, the hike is ((58000 − 50000) ÷ 50000) × 100 = 16% increase.
A jacket marked ₹2000 with a 30% off sale costs 2000 − (2000 × 0.30) = ₹1400 after the decrease.
If gold rose from ₹6000 to ₹6600 per gram, that is a ((6600 − 6000) ÷ 6000) × 100 = 10% increase.
Frequently asked questions
How do I calculate percentage increase?
Subtract the original value from the new value, divide the result by the original value, then multiply by 100. Formula: ((New − Original) ÷ Original) × 100. For example, an increase from 80 to 100 is ((100 − 80) ÷ 80) × 100 = 25%.
How do I calculate percentage decrease?
Use the same formula — ((New − Original) ÷ Original) × 100. When the new value is smaller, the result is negative, which means a decrease. For example, a drop from 1000 to 750 is ((750 − 1000) ÷ 1000) × 100 = −25%, i.e. a 25% decrease.
How do I increase or decrease a number by a percentage?
Multiply the value by the percentage as a decimal to get the change amount, then add it (for an increase) or subtract it (for a decrease). To increase 5000 by 15%: 5000 + (5000 × 0.15) = 5750. To decrease 1200 by 30%: 1200 − (1200 × 0.30) = 840.
Why do I divide by the original value and not the new value?
Percentage change is always measured relative to the starting point — the original value. Dividing by the new value gives a different, incorrect figure. For example, going from 80 to 100 is a 25% increase (20 ÷ 80), but coming back from 100 to 80 is a 20% decrease (20 ÷ 100). Same gap, different percentages, because the base changed.
Can a percentage increase be more than 100%?
Yes. If a value doubles, the increase is 100%; if it triples, it is 200% increase, and there is no upper limit. A decrease, however, can be at most 100% — that takes the value down to zero.
What does a negative percentage change mean?
A negative percentage change means the new value is lower than the original — that is a decrease. For example, if a price falls from ₹1000 to ₹750, the change is −25%.