Add/Subtract Percentage Calculator
Raise or lower a number by a percent—discounts, tax, tips, markups.
Add/Subtract Percentage Calculator
Calculate the result of adding or subtracting a percentage from a number
Quick Examples
Real-World Scenarios
Sales & Discounts
The formulas
Add p%
result = value × (1 + p/100)
$80 + 15% → 80 × 1.15 = $92
Subtract p%
result = value × (1 − p/100)
$80 − 25% → 80 × 0.75 = $60
Stacking percents is not additive. +10% then −10% does not return to the start (×1.1 × 0.9 = 0.99). Apply each change in order on the running total.
Everyday uses
- Sale price: subtract discount % from list
- Tax-inclusive total: add sales tax %
- Tip: add tip % to the bill (before or after tax—pick a rule and stick to it)
- Markup vs margin: markup is on cost; margin is on selling price—different bases
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Frequently Asked Questions
Percentage off vs percent of the sale price?
"20% off" means subtract 20% from the original. "20% of the sale price" is a different quantity—usually a fee or tax on the already-discounted amount.
Can I add percentages together?
Not as a shortcut for sequential changes. Multiply the factors instead (1.08 × 1.05 for +8% then +5%).
Quick tip math?
10% is move the decimal one place left; 20% is double that; 15% is 10% + half of 10%.
Negative numbers?
The same multipliers apply. Interpret carefully—"increase a loss by 10%" makes the magnitude larger (more negative if the value is negative).
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