OraUse the original value as the denominator
First find the absolute change: new minus initial. Divide that difference by the initial value, then multiply by 100. A positive result is an increase; a negative result is a decrease. Equal values give zero.
The U.S. Bureau of Labor Statistics percent-change explanation uses this difference-over-earlier-value method for index changes. Your two values must refer to the same unit and a comparable measure. The tool does not infer why a value changed.
From 100 to 125, then back again
For 100 to 125, the absolute increase is 25. Relative change = 25 ÷ 100 × 100 = 25%.
Reversing the direction uses a different baseline: 125 to 100 is −25 ÷ 125 × 100 = −20%. A 25% increase followed by a 20% decrease therefore returns to the starting value. Equal-sized changes in the numbers do not necessarily have equal-sized percentage changes.
Percent is different from percentage points
If a rate moves from 4% to 5%, the difference is one percentage point. Relative to the starting rate, it is (5 − 4) ÷ 4 × 100 = 25%. Those are two correct descriptions of different quantities.
Enter both values on the same scale: 4 and 5, or 0.04 and 0.05. Mixing 4 with 0.05 produces a misleading comparison. This calculator returns relative percent change and ordinary numeric difference; it does not automatically label a rate difference as percentage points.
For a positive starting investment and a stated number of years, the CAGR calculator answers the separate annualized-growth question. If the comparison concerns spending capacity, read the inflation and real-return guide before interpreting a percentage increase as an improvement.
Zero and negative baselines need a different question
A zero starting value would divide by zero, and negative starting values can create counterintuitive sign conventions. This tool rejects both rather than choosing a hidden policy for profit or loss comparisons.
The new value may be zero or negative when the starting value is positive. For example, 100 to zero is −100%; 100 to −25 is −125%. Decimal calculations use ordinary numerical precision and may need sensible rounding. The result is a total change, not an annualized return: use CAGR only when its endpoint and no-interim-cash-flow assumptions fit.
Common questions
Why does reversing the values change the percentage?
The denominator changes. A change of 25 is 25% of 100 but 20% of 125.
Can I start from zero or a negative number?
No. This tool uses positive baselines only. It does not silently choose a convention for undefined or negative-base comparisons.
Is this the annual growth rate?
No. It measures the total relative change between the two values. Annualizing requires a duration and a suitable growth model.
Educational estimate using the stated assumptions. Fees, taxes, changing rates and individual circumstances can change an outcome. This is not personalized financial advice. Read the estimates disclaimer.