Four percentage calculators in one place. Calculate percentages instantly — tips, discounts, grades, tax, and more.
Percentages are one of the most practical math concepts in everyday life. Whether you're calculating a restaurant tip, figuring out how much you save during a sale, checking your exam grade, or analyzing business data, percentages come up constantly. This guide explains the four most common percentage calculations with clear formulas and real-world examples.
This is the most common percentage question. To find a percentage of a number, multiply the number by the percentage and divide by 100.
Formula: Result = (Percentage ÷ 100) × Number
Example: What is 15% of 200?
= (15 ÷ 100) × 200 = 0.15 × 200 = 30
Real-life uses for this formula include calculating tips at restaurants, finding the tax amount on a purchase, determining how much you save with a coupon, and calculating a commission on a sale. For instance, if a salesperson earns a 7% commission on a $3,500 sale, they earn $3,500 × 0.07 = $245.
This formula answers questions like "What grade did I get?" or "What percentage of the budget did I spend?" Divide the part by the total and multiply by 100.
Formula: Percentage = (Part ÷ Total) × 100
Example: 30 is what percent of 200?
= (30 ÷ 200) × 100 = 15%
This is the formula behind grade calculations. If you scored 87 correct answers out of 100 questions, your score is (87 ÷ 100) × 100 = 87%. If you spent $450 out of a $600 monthly budget, you used (450 ÷ 600) × 100 = 75% of your budget. In nutrition, if a meal has 25g of protein and you need 150g daily, that meal covers (25 ÷ 150) × 100 = 16.7% of your daily protein goal.
Percentage change tells you how much something has grown or shrunk relative to its original value. It's used constantly in finance, business, and health tracking.
Formula: % Change = ((New Value − Old Value) ÷ Old Value) × 100
Increase example: Price went from $80 to $100
= ((100 − 80) ÷ 80) × 100 = +25% increase
Decrease example: Subscribers went from 1,200 to 900
= ((900 − 1,200) ÷ 1,200) × 100 = −25% decrease
Percentage change is essential for understanding salary raises — if your salary goes from $52,000 to $55,000, that's a ((55,000 − 52,000) ÷ 52,000) × 100 = 5.77% raise. In fitness, if you weighed 180 lbs and now weigh 162 lbs, that's a 10% reduction. In investing, if a stock went from $24 to $31.20, that's a 30% gain.
A common confusion: a 50% increase followed by a 50% decrease does NOT return to the original value. If you start at 100, gain 50% to reach 150, then lose 50%, you end up at 75 — not 100. This is why percentage changes are always calculated relative to the current base value.
This reverse calculation is useful when you know a partial value and the percentage it represents, and you need to find the whole. Common scenarios include VAT calculations and reverse discounts.
Formula: Original = (Value ÷ Percentage) × 100
Example: 30 is 15% of what number?
= (30 ÷ 15) × 100 = 200
Practical applications: if a store item is on sale for $68 after a 15% discount, the original price was $68 ÷ (1 − 0.15) = $80. If a tax amount of $12 represents 8% sales tax, the pre-tax price was (12 ÷ 8) × 100 = $150. If you need 2,400 calories and that's 80% of your calculated TDEE, your full TDEE is (2,400 ÷ 80) × 100 = 3,000 calories.
Standard tips are 15–20% of the pre-tax bill. On a $65 bill: 15% = $9.75, 18% = $11.70, 20% = $13. Use the tip shortcuts in Calculator 1.
A 30% discount on a $120 item saves you $36 (= 120 × 0.30), so you pay $84. Use Calculator 3 to verify the final sale price against the advertised discount.
In most US states, sales tax ranges from 4% to 10%. On a $250 purchase with 8.5% tax, you'll pay an extra $21.25 (= 250 × 0.085), totaling $271.25.
Score 43 out of 50 on a test? That's (43 ÷ 50) × 100 = 86%. Use Calculator 2 and the grade shortcuts to instantly convert any raw score to a percentage grade.
Use Calculator 3 to find out what percentage raise you're receiving. From $58,000 to $62,000 = ((62,000 − 58,000) ÷ 58,000) × 100 = 6.9% raise.
A savings account paying 4.5% APY on $5,000 earns $225 per year. Use Calculator 1: 4.5% of 5,000 = 225. Compound interest builds on this base each year.
When calculating tips at a restaurant, a quick mental trick is to find 10% first (just move the decimal point one place left), then adjust. For a 20% tip, simply double the 10% amount. For 15%, take 10% and add half of that again.
For discounts, remember that a 50% discount followed by another 50% discount is NOT a 100% discount — it's actually 75% off. The second 50% is calculated on the already-reduced price. Always work each discount step sequentially.
When comparing percentage changes, always be aware of the base. A startup going from 10 customers to 20 customers is a 100% increase, while a company going from 1,000,000 to 1,010,000 customers is only a 1% increase — even though the absolute growth (10 vs. 10,000 customers) looks very different in raw numbers.
These two terms are often confused but mean very different things. If interest rates rise from 4% to 6%, that is a 2 percentage point increase — but it is a 50% increase in interest rates (because (6−4)÷4 × 100 = 50%). Similarly, if your conversion rate improves from 2% to 3%, that's a 1 percentage point gain but a 50% relative improvement. Always clarify which you mean when discussing changes.
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