How do I calculate percentage of a number?

To find X% of Y: multiply Y by X and divide by 100. Example: 20% of 500 = (500 × 20) ÷ 100 = 100. FinanceKit Pro's percentage calculator does this instantly.

How do I calculate percentage increase?

Percentage increase = ((New Value − Old Value) ÷ Old Value) × 100. Example: price rose from $80 to $100, increase = ((100−80)÷80)×100 = 25%.

How do I calculate percentage decrease?

Percentage decrease = ((Old Value − New Value) ÷ Old Value) × 100. Example: salary cut from $5,000 to $4,000 = ((5000−4000)÷5000)×100 = 20% decrease.

What is a reverse percentage calculator?

A reverse percentage calculator finds the original value before a percentage was applied. If $120 is 20% more than the original, the original = 120 ÷ 1.20 = $100.

How do you find what percentage one number is of another?

Formula: (Part ÷ Total) × 100. Example: 45 is what % of 180? (45÷180)×100 = 25%. Use this for test scores, ratios, or any proportion.

How do I calculate percentage difference between two numbers?

Percentage difference = |V1 − V2| ÷ ((V1 + V2) ÷ 2) × 100. This is used when neither value is the 'original', such as comparing two measurements or prices.

How do I calculate a tip using percentage?

Tip amount = (Bill Amount × Tip %) ÷ 100. For a $85 restaurant bill with 18% tip: tip = (85 × 18) ÷ 100 = $15.30. Total = $100.30.

What is the percentage formula for a discount?

Discount amount = (Original Price × Discount %) ÷ 100. Final price = Original − Discount. Example: 30% off $250 = $75 discount, final price = $175.

✦ Free Tool — No Sign‑Up

Free Percentage Calculator Online 2026

Calculate % of a number, percentage increase/decrease, reverse percentage, tip, discount and more — instantly, for free, in any currency.

⚡ Instant Results 🌍 170+ Currencies 📋 Copy Results

📡 Today's Live Rates loading...

🥇 Gold / oz

—

₿ Bitcoin

—

💱 EUR / USD

—

📈 S&P 500

—

Find what X percent of a number equals. Perfect for calculating discounts, taxes, commissions, and more.

Percentage (%)

Number

Result

—

Find what percentage one number is of another. Useful for test scores, survey results, or ratios.

Part (X)

is % of

Total (Y)

Result

—

Calculate the percentage increase from one value to another. Ideal for salary raises, price hikes, investment returns, and GDP growth.

Original Value

→

New Value

Percentage Increase

—

Find the percentage drop between two values. Perfect for price drops, depreciation, weight loss, or market corrections.

Original Value

→

New Value

Percentage Decrease

—

Find the original value before a percentage was added or removed. Used for VAT/GST, price-before-discount, and salary-before-deductions.

Final Value (after %)

Percentage Applied (%)

% was Added % was Removed

Original Value (before %)

—

% Amount

—

Calculate the percentage difference between two values when neither is the reference point. Useful for comparing measurements, prices, or data sets.

Value 1

Value 2

Percentage Difference

—

Calculate tip amounts for restaurants, or find the final price after a discount. Widely used in the US, UK, Canada, UAE, and Australia.

Bill / Original Price

Tip / Discount %

🍽️ Restaurant Tip 🏷️ Discount

Tip Amount

—

Total Bill

—

📊 Today's Major Exchange Rates — —

Pair	Rate (vs USD)	% Today	Prev. Close
Loading rates...

What Is a Percentage Calculator — and How Does It Work?

A percentage calculator is an online tool that helps you compute any kind of percentage-based problem in seconds — whether you need to find what 20% of $500 is, calculate a salary increase of 8%, reverse-engineer the original price before VAT, or figure out the percentage difference between two stock prices.

FinanceKit Pro's free percentage calculator covers seven distinct calculation modes: percentage of a number, X is what % of Y, percentage increase, percentage decrease, reverse percentage, percentage difference, and a combined tip/discount tool. All results update instantly and respect your chosen display currency.

Core Percentage Formulas Explained

% of a Number

Formula: Result = (P ÷ 100) × N
Example: 20% of 500 = (20 ÷ 100) × 500 = 100

X is What % of Y?

Formula: % = (X ÷ Y) × 100
Example: 45 is what % of 180? (45 ÷ 180) × 100 = 25%

Percentage Increase

Formula: % = ((New − Old) ÷ Old) × 100
Example: $80 → $100 = ((100−80) ÷ 80) × 100 = 25%

Percentage Decrease

Formula: % = ((Old − New) ÷ Old) × 100
Example: $5,000 → $4,000 = ((5000−4000) ÷ 5000) × 100 = 20%

Reverse Percentage

Formula (% added): Original = Final ÷ (1 + P/100)
Example: $120 after +20% → 120 ÷ 1.20 = $100

Percentage Difference

Formula: % = |V1−V2| ÷ ((V1+V2)/2) × 100
Example: 90 vs 110 → |90−110| ÷ 100 × 100 = 20%

Real-World Examples — Who Uses a Percentage Calculator?

Investors and traders in the US, UK, Canada, and Australia use percentage calculators daily — to measure portfolio returns, compare stock performance, and size position changes. For example: if your S&P 500 ETF rose from $420 to $487, the gain is ((487−420)÷420)×100 = 15.95%.

Shoppers across the UAE, UK, Germany, and the US rely on the discount calculator: a $250 jacket on 30% sale becomes $175 (saving $75). The tip calculator is especially popular in the US and Canada, where 15–20% gratuities are standard at restaurants.

Business owners and accountants use the reverse percentage tool to strip tax from prices. If a product costs $118 including 18% GST/VAT, the pre-tax price = 118 ÷ 1.18 = $100 exactly.

Students and teachers globally use "X is what % of Y" to convert raw test scores. If a student scores 72 out of 90, that's (72÷90)×100 = 80%.

❓ Frequently Asked Questions

Select the "% of Number" tab above. Enter the percentage (e.g. 20) and the number (e.g. 500), then click Calculate. The result (100) appears instantly. The formula is: Result = (Percentage ÷ 100) × Number. FinanceKit Pro does this for free with no sign-up required.

Percentage Increase = ((New Value − Old Value) ÷ Old Value) × 100. Example: your salary went from $60,000 to $65,400 — the increase is ((65400−60000)÷60000)×100 = 9%. Use the "% Increase" tab in our calculator above to get instant results.

Percentage Decrease = ((Old Value − New Value) ÷ Old Value) × 100. If a stock fell from $180 to $135, the loss = ((180−135)÷180)×100 = 25%. Investors use this to measure drawdown. Use the "% Decrease" tab above for immediate results.

A reverse percentage calculator "unwinds" a percentage from a final value. If a price includes 20% VAT (UK standard rate), divide the total by 1.20 to find the pre-VAT amount. For 18% GST (India), divide by 1.18. Our "Reverse %" tab handles both "% was Added" and "% was Removed" scenarios.

Percentage change (increase/decrease) uses one number as the reference point (the "original" value). Percentage difference treats both values equally — it measures how far apart they are relative to their average. Use % change for before-and-after comparisons; use % difference when comparing two independent values with no clear "original."

The standard tip rate in the US is 15–20%. In the UK, 10–12.5% is common. Canada follows US norms at 15–20%. Tip is rarely expected in UAE but 10% is appreciated. Use the "Tip / Discount" tab: enter the bill amount, select your %, and get the tip and total instantly. Quick buttons for 10%, 15%, 18%, 20%, and 25% make it even faster.

Yes. Toggle the "🏷️ Discount" radio button in the Tip / Discount tab. Enter the original price and the discount percentage, and the tool shows both the discount amount and the final price immediately. For example: 30% off $250 = $75 discount, final price = $175.

Financial advisors widely recommend the 50/30/20 rule: 50% of after-tax income for needs, 30% for wants, and 20% for savings/debt. If you earn $5,000/month after tax: 20% = $1,000 to savings. Use our "% of Number" tab to calculate your target savings amount instantly.

🔗 Related Free Tools

🕒 Page last updated: April 30, 2026 · Data auto-refreshes every 5 minutes · All calculations are performed locally in your browser — no data sent to servers.