Percentage Change Calculator: From One Number to Another
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Percentage Change Calculator
Percentage change measures how much a value moved from one number to another, relative to where it started — with a sign. Prices, stock quotes, website traffic, weight, KPIs: whenever "before" and "after" matter, this is the right metric. Enter the old and new values and the calculator returns the signed change, the formula, and the absolute difference.
The percentage change formula
Percentage change = ((New − Old) ÷ Old) × 100
Example: a subscription went from 50 to 60. The change is (60 − 50) ÷ 50 × 100 = +20%. If it later dropped back to 50, that move is (50 − 60) ÷ 60 × 100 = −16.67% — a different magnitude, because the starting base changed.
Change vs. increase vs. difference
These three sound alike but answer different questions. Percentage change is signed and time-directed (this page). The percentage increase calculator frames the same math as growth or reduction, and also applies a percentage to a number. The percentage difference calculator is direction-free — it compares two values of equal standing against their average, so it's the one to use when neither number is the "starting point".
Applying a change to a value
The second mode goes the other way: given a starting value and a percent change (positive or negative), it returns the final value. A −12.5% change on 50 gives 50 × (1 − 0.125) = 43.75. Handy for projecting a price after an announced increase, or a portfolio after a drop.
FAQs
Subtract the old value from the new value, divide by the old value, then multiply by 100. From 50 to 60: (60 − 50) ÷ 50 × 100 = +20%. From 60 to 50: (50 − 60) ÷ 60 × 100 = −16.67%.
Percentage change = ((New value − Old value) ÷ Old value) × 100. A positive result means the value went up; a negative result means it went down.
Percentage change has a direction: it measures how a value moved from an old number to a new one. Percentage difference is direction-free: it compares two equally-valid values against their average. Use change for prices and KPIs over time, difference for comparing two things.
Enter the earlier price as the old value and the current price as the new value. A stock that moved from 42.50 to 39.10 changed by (39.10 − 42.50) ÷ 42.50 × 100 = −8%.
Yes. If a value more than doubles, the change exceeds +100%. From 40 to 100 the change is +150%. A decrease, however, can never go below −100% (a drop to zero).