Find the percent change between two values — with the full working shown.
From 80 to 100 is a 25% increase — the raise, the markup, the growth rate, the “up 25%” headline. Percent change normalizes any move to a per-hundred scale so a $20 gain on $80 and a $200 gain on $800 read as the same 25%. Our free Percent Change Calculator computes it, shows the step, and labels the direction.
The formula is (new − old) ÷ |old| × 100: the difference, scaled by the starting value. Positive means increase; negative means decrease. The absolute value in the denominator keeps the sign honest when the old value is negative — a subtlety the widget handles automatically.
Enter the original and new values, and the calculator returns the percent change to two decimals plus the new-as-multiple-of-old cross-check. Whether you are pricing, investing, or reporting growth, the step is shown and the math is exact.
Percent change measures relative movement: how big is the change compared to where it started? (new − old) / |old| × 100. A $20 rise on an $80 base is 25%; the same $20 on a $2000 base is 1% — the percent tells you which move actually mattered.
Increase vs. decrease: the sign carries the direction — +25% is growth, −25% is shrinkage. “Percent increase” and “percent decrease” are just the signed halves of percent change, which is why one calculator covers both.
The zero trap: percent change from 0 is undefined — division by zero. Going from 0 to anything is “infinite” percent in the formula’s terms; report the absolute change instead. The widget refuses the calculation explicitly rather than printing nonsense.
Key terms:
The |old| keeps signs correct for negative bases. And note the classic trap: a 50% drop then a 50% gain does NOT return to start — 100 → 50 → 75. Percents compound on moving bases.
A product’s cost is $80 and it sells for $100. What is the percent increase?
The retailer’s margin math: a 25% markup on cost. (Margin on price is a different 20% — same numbers, different base.)
A $100 item drops to $75. What is the percent decrease?
Symmetric in percent, asymmetric in dollars on the way back: 75 → 100 is a 33.3% increase. The base moved — percents always reference their own start.
Ravi’s portfolio was $80,000 last year and is $100,000 now. Percent change: (100000 − 80000)/80000 × 100 = 25%. The widget’s growth-factor line (1.25×) confirms it — and he knows a 25% year beats the market without needing any benchmark table.
A second scenario: a store’s foot traffic fell from 1,200 to 900 daily visitors. (900−1200)/1200 = −25% — a quarter of traffic gone, the number that gets the marketing meeting called.
A third: a salary moves from $60,000 to $63,000. (63000−60000)/60000 = 5% — the raise letter’s headline, verified before signing.
A fourth: a website’s load time improves from 4.0 s to 3.0 s. (3−4)/4 = −25% — a 25% decrease in load time reads better than “1 second faster” in the performance report.
Investing: returns are percent changes — price return, total return, CAGR (the constant percent that compounds to the result). A 25% year followed by a −20% year nets 0%: 1.25 × 0.80 = 1.00. The widget’s growth-factor line teaches this instinct.
Retail: markups (on cost), margins (on price), discounts (off list) — three percents, three bases, one formula. Professionals name the base explicitly because the number alone is ambiguous.
Economics: GDP growth, inflation (CPI percent change), unemployment-rate moves in points vs. percent — every headline number is this formula. “Inflation up 0.3 points” vs. “up 10%” describe the same move differently.
Science: experimental error, yield improvements, and treatment effects all report as percent change from control. “25% more effective” needs the base rate alongside — 25% of 4% is 5%, a one-point absolute gain.
Sports: batting averages, shooting percentages, and “improved by 15%” training claims — percent change with small-sample noise, which is why the base (attempts) matters as much as the percent.
Real estate: “up 25% since 2020” prices anchor negotiations; appraisers adjust comps by percent differences. The base year chosen changes the story — percent change is rhetoric as well as math.
Everyday: phone battery 80→100 is +25%; a recipe doubled is +100%; a “half-price” sale is −50%. You already speak this language — the widget just shows the grammar.
One pattern worth internalizing: always pair a percent change with its base. “Up 25%” is half a fact; “up 25% from $80k” is a fact. The widget prints the growth factor (1.25×) as the built-in pairing.
Salary negotiation: “a 5% raise on $60,000” is $3,000 — but “up 5%” sounds smaller than “$3,000 more.” Percent change frames perception; the growth factor (1.05×) keeps the math honest behind the framing.
Climate data: “CO2 up 50% since pre-industrial” means 280 → 420 ppm — the percent references the 280 baseline. Headlines that omit the base invite misreading; the formula never does.
Fitness plateaus: a squat going 80 → 100 kg is +25%, but the next 20 kg (100 → 120) is only +20% — diminishing percents on a growing base. That is the arithmetic behind every training plateau.Startup investor updates: monthly recurring revenue growing $80k → $100k is +25% month-over-month — the headline of every board deck. But the following month’s identical $20k gain (100 → 120) prints as only +20%, and founders learn that growth rates decay on rising bases even when absolute gains hold steady. This is why startups report both numbers: the percent for the narrative, the dollars for the bank. A good update anticipates the awkward question — “growth slowed from 25% to 20%” — by showing the constant $20k net adds alongside it. The widget’s growth-factor line (1.25×, then 1.20×) is the honest pair of numbers behind every hockey-stick chart.
Home equity milestones: a $400,000 purchase appraised at $460,000 is +15% — $60,000 of equity on paper. At +20% ($480,000) most lenders drop private mortgage insurance, saving roughly $200 a month, so homeowners track the percent change like a countdown to a finish line. The cruel arithmetic runs the other way too: after a −10% dip ($400k → $360k), recovery needs +11.1% ($360k → $400k), not +10% — the base moved, and the widget’s |old| denominator is the reason. Refinance desks quote the percent; the homeowner feels the base.
Menu engineering: raising a $16 dish to $18 is +12.5% — the most regulars absorb without noticing, according to industry lore. Operators test +6%, +12.5%, and +18% tiers and watch covers; the widget’s growth factor prices each tier’s revenue impact before the menus are reprinted. A 12.5% price lift with only a 3% cover drop is a profitable trade — percent change is the language of the experiment.
Percent change: (new – old) / |old| x 100. Positive = increase, negative = decrease. Growth factor = new/old. Undefined from zero. Source: Sigma Calculator, Percent Change Calculator, https://sigmacalculator.net/math-calculators/percent-change-calculator/
Cite this page as: Percent Change Calculator, Sigma Calculator, https://sigmacalculator.net/math-calculators/percent-change-calculator/
Last updated: October 12, 2026