Calculate the percentage change between any two values. Auto-detects increase or decrease — enter old and new values to get your result with full working shown.
Enter your original (old) value and new value. The calculator auto-detects whether the change is an increase or decrease.
Enter the original value and the percentage change (use negative values for decreases) to find the resulting new value.
Know the new value and the % change applied? Work backwards to find what the original value was before the change.
A percentage change measures how much a value has shifted — up or down — relative to its starting point. It is the most versatile of all percentage calculations because it handles both growth and reduction in a single formula. Percentage change is used in finance (investment returns, inflation), business (month-over-month revenue growth), science (experimental data changes), and everyday life (tracking weight, scores, utility bills, and more).
The key advantage of our percentage change calculator over separate increase/decrease tools is that you don't need to know in advance whether the value went up or down — simply enter the old and new values and the result auto-labels the direction for you.
% Change = ((New Value − Old Value) ÷ |Old Value|) × 100
The vertical bars (| |) around Old Value mean you use its absolute value as the divisor — this matters when the original value is negative (common in financial loss scenarios). A positive result means the value increased. A negative result means the value decreased.
Old = 100, New = 130
% Change = ((130−100)÷100)×100 = +30%
Old = 100, New = 75
% Change = ((75−100)÷100)×100 = −25%
Question: Revenue was $24,000 in January and $18,000 in February. What is the % change?
Step 1: Difference = $18,000 − $24,000 = −$6,000
Step 2: Divide: −$6,000 ÷ $24,000 = −0.25
Step 3: Multiply: −0.25 × 100 = −25% (a 25% decrease)
Percentage increase and percentage decrease are specialised versions of percentage change — they each apply only to one direction. Percentage change is the umbrella formula that covers both. If you know the direction in advance, use the dedicated calculator for cleaner results. If you're unsure, use this percentage change calculator and it will label the result automatically.
Percentage change always has a clear reference point (the old/original value) and the result is directional. Percentage difference, however, treats both values as equal — it has no "before" or "after," and always produces a positive result. Use percentage change for time-series or before/after comparisons. Use percentage difference when comparing two independent measurements of equal standing, such as two lab readings or two competitors' prices.
| Scenario | Old Value | New Value | % Change |
|---|---|---|---|
| Monthly sales | $18,000 | $22,500 | +25% |
| Annual inflation | $1.80/L petrol | $2.07/L | +15% |
| Weight loss | 95 kg | 80.75 kg | −15% |
| Stock value drop | $250 | $187.50 | −25% |
| Website traffic growth | 8,000 visits | 11,200 visits | +40% |
| Energy bill reduction | $320 | $256 | −20% |
When the old value is negative (e.g., a business loss improving from −$5,000 to −$2,000), the formula still works — you divide by the absolute value of the old number: ((−2,000 − (−5,000)) ÷ |−5,000|) × 100 = (3,000 ÷ 5,000) × 100 = +60%, meaning the loss improved by 60%. According to standard accounting and financial reporting conventions (Investopedia), the absolute value denominator is the accepted approach for such edge cases.
Common questions about calculating percentage change
% Change = ((New Value − Old Value) ÷ |Old Value|) × 100. A positive result means an increase; a negative result means a decrease. The formula divides by the absolute value of the old number to handle negative starting values correctly.
1. Subtract the old value from the new value to get the difference. 2. Divide the difference by the old value. 3. Multiply by 100. Example: old = 50, new = 65 → ((65 − 50) ÷ 50) × 100 = +30%. Use the calculator above for instant results.
Yes — a negative percentage change means the value decreased. Example: old = 200, new = 150 → ((150 − 200) ÷ 200) × 100 = −25%. This is equivalent to a 25% decrease. Our calculator displays the direction label automatically.
Percentage change requires a clear old/new reference — it's directional and divides by the original value. Percentage difference has no reference point, uses the average of both values as the denominator, and always gives a positive result. Use change for before/after; use difference for two independent equal-standing values.
Percentage increase only applies when the value went up and is always expressed as a positive number. Percentage change covers both directions — a positive % change is an increase; a negative % change is a decrease. Both use the same formula but percentage change labels the direction in the result automatically.
Formula: New Value = Old Value × (1 + % Change ÷ 100). Use negative % for decreases. Example: increase $400 by 20% → $400 × 1.20 = $480. Decrease $400 by 15% → $400 × 0.85 = $340. Use the "Find New Value" tab in the calculator above.
No — division by zero is mathematically undefined, so percentage change cannot be calculated when the old value is zero. In such cases (e.g., going from $0 revenue to $1,000), the change is described as "new" or "infinite" rather than as a percentage. Our calculator will flag this as an error and ask you to enter a non-zero old value.