Percentage change in geography
How big is a change compared with where it started?
Find the change, divide by the original value, then multiply by 100.
Use the starting value
The same rise can mean different things. Ten more buses is a large change for a village with 20 buses, but a small change for a city with 200.
Read the sign
A positive result is an increase. A negative result is a decrease. A percentage change is different from the percentage of a total.
Worked example
| Daily passengers on an invented route |
|---|
| Original: 80 · New: 100 |
- Change = 100 − 80 = 20 passengers.
- Divide by the original: 20 ÷ 80 = 0.25.
- Multiply by 100: 0.25 × 100 = 25%. Passenger numbers increased by 25%.
If the original value is zero, this formula cannot give a percentage change. State the numerical change instead. A rise from 20% to 30% is 10 percentage points, or a 50% relative increase.
Check you’ve got it
Passenger numbers fall from 100 back to 80. Is that a 25% decrease?
Check your answer
No. The new starting value is 100. (80 − 100) ÷ 100 × 100 = −20%, a 20% decrease.
Try it yourself
Use this new resource. Check your answers, then try another set.
Percentage change
The starting year is the denominator. A negative percentage indicates a decrease.
| Year | Visitors |
|---|---|
| 2020 | 2300 |
| 2025 | 2530 |
Resource description
Fictional nature reserve annual visits
Your course and question context
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