Percentage Increase and Change Calculator — 4 Modes

Percentage increase starts from a known original value and applies a known percentage rise. A $50,000 salary raised by 10% becomes $55,000. The percentage decrease formula is the mirror image — useful for discounts, depreciation, and price drops.

Percentage change compares two known values and reports the result as positive or negative. Going from 80 to 100 is a +25% change; going from 100 to 80 is a -20% change. The reference point is always the original value, which is why the same absolute difference produces different percentages depending on direction.

Percentage difference compares two values symmetrically — neither is treated as the original. It uses the average of the two values as the reference point and is always positive. Scientists and engineers often prefer it when comparing measurements where there is no natural "before" or "after."

Use percentage increase or decrease when you already know the original and want to apply a percentage. Use percentage change when you have a before and an after. Use percentage difference when the two values are peers — two lab measurements, two competitor prices — and you just want to quantify the gap.