Percentage Calculator. Calculate percentages in seven modes with visible formulas, strict input validation, signed percentage change, and symmetric percentage difference.
Choose your path
Select one of seven percentage questions and receive a strict, reproducible result with the correct denominator and visible steps.
Find a portion or increased/decreased amount without choosing the wrong operation.
Select the matching plain-language tab, enter both values, and inspect formula and steps.
Can distinguish “of” from “increase/decrease by” and copy the exact calculation.
Measure change or symmetric difference without a negative denominator artifact.
Use change for an ordered baseline or difference for an unordered pair, including negative values.
Understands absolute-baseline change and receives 200% difference for −10 versus 10.
Switch among seven modes and enter values without inaccessible tabs or silent defaults.
Navigate the tablist with arrow/Home/End keys or horizontal mobile scrolling, then edit named inputs.
Blank/invalid input remains an explicit empty/error state and no result masquerades as zero.
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To find X% of Y, multiply Y by X and divide by 100.
Result = Y × (X / 100)Percentage change shows how much a value has increased or decreased relative to its original value.
% Change = ((New - Old) / |Old|) × 100When you know the final amount after a percentage increase or decrease, divide by the multiplier to recover the original value.
Original = Final ÷ (1 ± Rate/100)Updated: July 2026
Calculate the sale price when a $80 item is 25% off.
→ Final price: $60 (save $20)
Calculate the percentage increase from $50,000 to $55,000.
→ 10% increase
A retailer adds 35% markup to a $40 wholesale cost to set the selling price.
→ Selling price: $54
Markup is added to cost (35% markup on $40 = $54). Margin is profit divided by selling price (35% margin on $40 cost = $61.54 selling price). They use different denominators.
20% of $100 = $20, but 20% off $100 = $80. These are different operations — 'of' means multiply, 'off' means subtract the percentage from the total.
A 10% increase followed by a 10% decrease does not return to the original value — you end up at 99% of the starting amount. Percentage changes are always relative to the current value.
Choose one of seven explicit modes for portions, ratios, change, symmetric difference, increases, decreases, or fraction conversion. Blank and invalid fields are never silently treated as zero.