Percentage Change Calculator

How to calculate percentage change

1. Enter the original value: the starting amount you want to compare against.
2. Enter the new value using the same units and comparison basis. A point or comma is a decimal separator, not digit grouping.
3. Read the percentage increase or decrease and the signed numeric change. A zero original has no defined percentage; a negative original uses the method explained beside the result.
4. Open Calculation details to check the method, copy the qualified result if useful, or clear both values to start again.

A focused original-to-new comparison

• Calculate a percentage increase or decrease from two known values.
• See the exact signed numeric change alongside the percentage.
• Enter positive, negative or zero values with up to four decimal places.
• Keep zero-baseline, negative-baseline and very small changes clearly qualified.
• Check the formula and copy the result without creating an account or uploading a file.

When this comparison is useful

• Compare two prices in the same currency and on the same basis, without a currency conversion.
• Compare counts or quantities for like-for-like periods, such as items produced in two equal-length periods.
• Check an original-to-new percentage calculation or understand why reversing the values changes the answer.

Understanding the percentage and numeric change

The numeric change is the new value minus the original value. For a nonzero original, this tool divides that change by the absolute original value and multiplies by 100. With a positive original, this is the familiar original-value formula.

Increase and decrease describe movement on the number line, not whether something improved. A negative original is compared by its size without its minus sign. Other conventions exist; this result is not an investment return or a universal profit-growth measure.

Compare like with like: use the same units, currency, reference basis and suitable periods. A percentage is only meaningful for a suitable scale; Celsius and Fahrenheit temperature changes should not be interpreted this way.

Starting from zero gives no defined percentage change because the formula would divide by zero. This remains true for zero to zero. The numeric change can still be calculated and copied.

Percentage change and percentage points are different. Moving from 5 to 6 is a 20% relative increase. If those values are rates of 5% and 6%, their raw gap is one percentage point.

Entered decimals are calculated exactly. The percentage is shown with up to three decimal places; About identifies rounding. A nonzero result below 0.001% is labelled as smaller than that amount, never as no change.

Percentage change examples

From 80 to 100, the numeric change is +20. Dividing 20 by the original 80 gives a 25% increase.

From 100 to 80, the change is −20 and the result is a 20% decrease. Reversing the comparison gives a 25% increase, not 20%, because the original value changes.

From 5 to 6, the change is +1 and the relative increase is 20%. When these numbers represent percentage rates, that +1 is one percentage point.

From −100 to −50, the numeric change is +50. Under this tool's absolute-original convention, the result is a 50% numerical increase, not a claim about profit or performance.

From 0 to 10, the numeric change is +10 but the percentage is undefined. From 0 to 0, the numeric change is 0 and the percentage is still undefined.

What the calculator does not decide

Each value must be between minus one billion and one billion with up to four decimal places. Enter ungrouped ASCII digits with an optional leading plus or minus sign; for example, 1,000 is one.

This is one original-to-new comparison. It does not calculate symmetric percentage difference, apply a known percentage, combine growth over time or solve a missing value.

A numerical answer does not validate the comparison basis, input measurements or an economic interpretation. Negative baselines and scales without a meaningful zero need particular care.

Only the displayed percentage is rounded. About and smaller-than qualifications remain part of the result when copied; extra display digits would not make uncertain measurements more accurate.

Your calculation inputs

The calculator keeps its inputs in page memory, with no account, uploaded file, saved history or input-bearing share link. Copy happens only when requested.

The surrounding website can make ordinary requests under its existing consent and analytics settings. Local arithmetic is not whole-site privacy certification.