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Percentage Calculator – Find % of a Number, Increase & Decrease

Calculate percentages instantly: what is X% of Y, percentage increase or decrease, reverse percentages, and percentage difference. Free online tool with step-by-step formulas.

Updated for 2026

By the GlobalCalqulate team, founded by Pavan Kusunuri · About our editorial standards

Percentage Calculation

Calculation Type

Value X

Value Y

Decimal Places

Show Formula

Result

200.00

(20 / 100) × 1000

Result

200.00

Formula Used

(20 / 100) × 1000

Step-by-Step Explanation

20% of 1000 = (20÷100) × 1000 = 200

✓ Reviewed and updated for accuracy using current official rates and widely accepted formulas.

How to Use This Calculator

Choose What to Calculate

Select from six common percentage scenarios: find X% of Y, what percent X is of Y, increase/decrease, reverse percentages, or percentage difference.

Enter Your Numbers

Input values for X and Y. For 'What is 20% of 1000?', enter 20 and 1000. For increase/decrease, enter old and new values.

View Results

Get the answer, the formula used, and step-by-step workings so you understand exactly how the calculation was done.

Understanding Your Results

Percentage
A part per hundred: (Part ÷ Whole) × 100. 20% means 20 out of every 100, or 0.20 as a decimal.
% Increase
((New − Old) ÷ Old) × 100. Measures growth. 100 → 120 = 20% increase.
% Decrease
((Old − New) ÷ Old) × 100. Measures decline. 100 → 80 = 20% decrease.
Reverse %
Found when you know a percentage and the result. Original = Final ÷ (1 + Rate) or Final ÷ (1 − Rate).

Key Tips

✓
10% of any number = divide by 10. 20% = double that. 5% = half of 10%.
✓
Percentage difference uses the average as base: |A−B| ÷ ((A+B)/2) × 100. Different from percentage change.
✓
When calculating a discount, subtract the discount from 1: 25% off = multiply by 0.75.
✓
A 50% loss requires a 100% gain to recover. If $100 drops to $50 (−50%), you need +100% to get back to $100.

Help & FAQs

Frequently Asked Questions

Clear answers to common questions to help you use this calculator confidently.

How do I calculate what percentage one number is of another?

Tap to view the answer

Divide the part by the whole, then multiply by 100. Formula: (Part ÷ Whole) × 100 = %. Example: What % is 25 of 200? (25 ÷ 200) × 100 = 12.5%.

What is the formula for percentage increase?

Tap to view the answer

Formula: ((New Value - Old Value) ÷ Old Value) × 100. Example: Salary increased ₹50,000 → ₹60,000. ((60000 - 50000) ÷ 50000) × 100 = 20% increase.

How to calculate percentage decrease?

Tap to view the answer

Same formula as increase: ((Old Value - New Value) ÷ Old Value) × 100. Example: Stock price ₹100 → ₹80. ((100 - 80) ÷ 100) × 100 = 20% decrease.

How to find the original price after a discount?

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Formula: Original Price = Final Price ÷ (1 - Discount%). Example: Item costs ₹600 after 25% discount. 600 ÷ (1 - 0.25) = 600 ÷ 0.75 = ₹800 original.

What is the difference between percentage increase and percentage difference?

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% Increase compares old vs new (directional). % Difference uses the average of the two values as base. Example: 100 → 120 is +20% increase. Comparing 100 vs 120 is ~18% difference.

How to calculate discount percentage while shopping?

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Discount % = ((Original Price - Sale Price) ÷ Original Price) × 100. Example: Shirt ₹1000 on sale ₹750 → 25% off.

What is GST calculation and how does it differ from discount?

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GST is added (not subtracted). Formula: Final Price = Original × (1 + GST%). Example: ₹1000 with 18% GST = ₹1180. Reverse = Final ÷ 1.18.

How to calculate percentage increase on salary or investment returns?

Tap to view the answer

Same formula: ((New - Old) ÷ Old) × 100. Salary ₹40k → ₹50k = 25% raise. Investment ₹1L → ₹1.5L = 50% return.

How to calculate test score or exam percentage?

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Formula: (Marks Obtained ÷ Total Marks) × 100. Example: 75 out of 100 = 75%. 280 out of 400 = 70%.

What is profit margin vs markup percentage?

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Margin = ((Revenue - Cost) ÷ Revenue) × 100. Markup = ((Revenue - Cost) ÷ Cost) × 100. Example: Cost ₹100, sell ₹150: Markup 50%, Margin 33.3%.

How to calculate percentage error in measurements?

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Formula: (|Measured - Actual| ÷ Actual) × 100. Example: Measured 98g, actual 100g → 2% error.

What are quick mental tricks to calculate percentages?

Tap to view the answer

10% rule: 10% = divide by 10. 20% = 10% × 2. 5% = 10% ÷ 2. 25% = ¼. 50% = ½. Example: 20% of ₹500 = ₹100.

How to calculate compound percentage increase over multiple years?

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Final = Initial × (1 + Rate)^Years. Example: ₹1L at 10% for 3 years = 100000 × (1.10)^3 = ₹1,33,100.

How to calculate percentage growth rate for business or investment?

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((Current - Previous) ÷ Previous) × 100. Example: Revenue ₹10L → ₹15L = 50% growth.

When should I use percentage vs absolute numbers?

Tap to view the answer

Use % for comparing different-sized groups, absolute numbers for actual values. Both are important.

How to calculate weighted percentage average?

Tap to view the answer

Formula: (Value1×Weight1 + Value2×Weight2) ÷ Total Weights. Example: Exam1 80 (60%), Exam2 90 (40%) → (80×0.6 + 90×0.4) = 84.

What's the difference between percentage point and percentage? How do you calculate it?

Tap to view the answer

Percentage point = absolute difference. Percentage = relative change. Example: 5% → 7% is +2 percentage points and 40% relative increase.

How to convert between percentage, fraction, and decimal?

Tap to view the answer

Percentage → Decimal: divide by 100. Decimal → Percentage: multiply by 100. Fraction → Percentage: (fraction)×100. Percentage → Fraction: put over 100 and simplify.

What is a basis point and where is it used?

Tap to view the answer

1 basis point = 0.01% = 0.0001 decimal. 100 bps = 1%. Used in finance for small changes in interest rates.

How do I calculate what percentage different amounts represent when they have different bases?

Tap to view the answer

Always divide by the base (the whole). Example: 50 managers out of 200 = 25%; 50 out of 400 = 12.5%.

Why does a 50% decrease require 100% increase to recovery?

Tap to view the answer

Because you lose 50% of the original value, then need 100% of the new value to get back. Formula: Recovery % = (X ÷ (100-X)) × 100.

How do I calculate percentage for very small values (like interest rates, error margins)?

Tap to view the answer

Use decimals. Example: 0.5% of ₹1000 = 0.005 × 1000 = ₹5. For tiny percentages, precision is key.

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How to Use This Calculator

Choose What to Calculate

Select from six common percentage scenarios: find X% of Y, what percent X is of Y, increase/decrease, reverse percentages, or percentage difference.

Enter Your Numbers

Input values for X and Y. For 'What is 20% of 1000?', enter 20 and 1000. For increase/decrease, enter old and new values.

View Results

Get the answer, the formula used, and step-by-step workings so you understand exactly how the calculation was done.

Understanding Your Results

Percentage
A part per hundred: (Part ÷ Whole) × 100. 20% means 20 out of every 100, or 0.20 as a decimal.
% Increase
((New − Old) ÷ Old) × 100. Measures growth. 100 → 120 = 20% increase.
% Decrease
((Old − New) ÷ Old) × 100. Measures decline. 100 → 80 = 20% decrease.
Reverse %
Found when you know a percentage and the result. Original = Final ÷ (1 + Rate) or Final ÷ (1 − Rate).

Key Tips

✓
10% of any number = divide by 10. 20% = double that. 5% = half of 10%.
✓
Percentage difference uses the average as base: |A−B| ÷ ((A+B)/2) × 100. Different from percentage change.
✓
When calculating a discount, subtract the discount from 1: 25% off = multiply by 0.75.
✓
A 50% loss requires a 100% gain to recover. If $100 drops to $50 (−50%), you need +100% to get back to $100.

How Percentages Work

The Basic Percentage Formula

Percentage = (Part ÷ Whole) × 100. To find 20% of 1,000: Part = 20/100 × 1,000 = 200. To find what percent 200 is of 1,000: Percent = (200 ÷ 1,000) × 100 = 20%. The calculator handles six common variations so you don't need to remember which formula to apply.

Percentage Change — Increase and Decrease

Percentage change answers: 'How much did this number go up or down, relative to where it started?' The formula is ((New − Old) ÷ Old) × 100. A positive result means increase; negative means decrease. This is different from percentage difference, which compares two numbers without direction using their average as the base. Use percentage change for tracking growth (revenue, prices, test scores); use percentage difference when comparing two independent values.

Reverse Percentage Calculations

Sometimes you know the final price after a discount and need to find the original. If an item costs $600 after a 25% discount: Original = $600 ÷ (1 − 0.25) = $600 ÷ 0.75 = $800. For increases (like tax or markup): Original = Final ÷ (1 + Rate). The calculator's reverse percentage mode handles both — just select the scenario.

Quick Mental Math Shortcuts

10% = divide by 10. 5% = divide by 20. 25% = divide by 4. 50% = divide by 2. 1% = divide by 100. For 15%, add 10% + 5%. For a 20% tip on $45: 10% = $4.50, double = $9. These shortcuts build number sense even when using a calculator.

1. Mixing Up "Percentage Point" vs "Percentage Change"

Interest rate goes 5% → 6%. Is that a 1% increase or 20% increase? Answer: 1 percentage point, but 20% relative increase. Wrong: "Interest rate up 1%, so that's 1% increase" (confusing). Correct: "Rate increased by 1 percentage point" or "Rate increased by 20% relatively".

2. Forgetting the Asymmetry of Increases/Decreases

Assuming a 50% increase followed by 50% decrease returns to original. It doesn't!. Wrong: ₹100 up 50% = ₹150. Down 50% = ₹75? NO, ₹75 is only 50% of ₹150. Correct: ₹100 up 50% = ₹150. To return to ₹100, need 33.33% decrease (not 50%).

3. Calculating Discount on Discounted Price

When stores say "30% off + 20% additional," don't add them to get 50% total off. Wrong: ₹1000 with 30% + 20% off = 50% off = ₹500. Correct: ₹1000 - 30% = ₹700. Then ₹700 - 20% = ₹560 (44% total, not 50%).

4. Confusing "Of" Language in Percentage

"20% more than 50" vs "20% of 50" are different!. Wrong: "20% more than 50" = 50 (treating it like just 20% of 50). Correct: "20% more than 50" = 50 + (20% of 50) = 50 + 10 = 60.

5. Ignoring Significant Figures

Reporting extreme precision when measurements don't warrant it. Wrong: "Discount is 33.3333333333%" (meaningless precision). Correct: "Discount is approximately 33%" or "33.33%" with 2 decimals max.

6. Applying Percentage to Already Percentage Values Incorrectly

Tax brackets, interest rates, and margins require careful handling. Wrong: "Tax of 18% on 50% discount" — which applies first?. Correct: Always specify: "18% tax on base price BEFORE discount" or "AFTER discount".

Golden Rules to Avoid Mistakes:

• Always identify the base value (what are we taking percentage of?). • Use a calculator for complex calculations—mental math leads to errors. • Check your answer with reverse calculation. • Be precise about what you're calculating: "% of total," "% increase," or "% change"?. • Remember: increases & decreases are not symmetric.

Why Percentage Calculations Matter

Struggling with percentage calculations? You're not alone. Whether you're calculating shopping discounts, salary increases, investment returns, exam scores, or GST taxes, percentages are everywhere—and easy to mess up. According to research, 73% of people make calculation errors with percentages, leading to poor financial decisions. You might think you're getting a 30% discount when it's really 25%. Or miss salary increase negotiations because you can't quickly validate the math. Our free percentage calculator solves this instantly, showing you the formula AND the answer so you actually understand what's happening. Real Impact: You're shopping in India and see "Original ₹1000, now 40% off!" Quick math in your head gets confusing. Our calculator: Enter 40% and 1000 → Instantly shows ₹400 discount, final price ₹600. Takes 5 seconds. No math errors. No buyer's remorse. Same logic applies to salary negotiations (Is 15% raise on ₹50k a good deal?), investment tracking (What's my 8% annual return in rupees?), and exam scores (What percentage did I actually get?).

Who Needs This Percentage Calculator?

• Shoppers & Deal Hunters: Verify discount percentages instantly. ₹1000 item with 25% off—is it really ₹250 savings? Check in 2 seconds. • Salary Negotiators: Evaluate salary increase offers quickly. ₹50k to ₹60k—that's a 20% raise. Worth it? Depends on inflation and your goals. • Investors & Business Owners: Calculate returns, growth rates, profit margins. ₹1 lakh invested at 12% annual return = ₹12,000 income/year. • Students & Teachers: Convert test scores to percentages. Scored 95 out of 120? That's 79.17%. Pass/fail cut-off is 40%? You easily cleared it. • GST & Tax Calculations (India): Add or remove 5%, 12%, or 18% GST from prices. ₹1000 item with 18% GST = ₹1180 final price. • Anyone Who Wants Accuracy: No more "does that sound right?" moments. See the exact formula and result every time. Quick Fact:. A percentage is simply a part of 100. When you see 25%, it means 25 out of 100, or 1/4 of something. This calculator helps you convert any numbers into percentages—or find percentages in real-world situations instantly, without mental math errors.

Percentage Increase Interpretation

1-5%. Minimal growth. Usually below inflation rate. For salary: keep negotiating. For investment: might be underperforming. 5-15%. Healthy growth. Matches or exceeds inflation. For salary: good offer, accept unless better options. For investment: meeting market expectations. 15-30%. Strong growth. Excellent for salary increases or investment returns. Negotiate for this range or take the deal if offered. 30%+. Exceptional growth. Unusual and typically unsustainable. For salary: verify realistic. For investment: check for hidden risk.

Percentage Decrease Caution

Decreases compound differently than increases. If something drops 50%, it needs a 100% increase to return to original. Example: ₹100 down 50% = ₹50. To return to ₹100, you need +100%, not +50%. This is why losses feel worse than equal-sized gains!. Percentage Increase Feels Good ₹100 → ₹150 (50% increase) feels like huge progress. Same % Decrease Hurts More ₹150 → ₹100 (33% decrease) feels worse, even though it's the same endpoint.

1⃣ Basic Percentage Formula

Percentage = (Part ÷ Whole) × 100. When to use: When you want to know what percentage one number is of another. Real example: You saved ₹25,000 towards a ₹1,00,000 goal. What percentage is that? (25,000 ÷ 1,00,000) × 100 = 25% of your goal. Pro Tip: The formula works for ANY percentage question that starts with "What percent is X of Y?".

2⃣ Percentage Increase/Decrease Formula

% Change = ((New Value - Old Value) ÷ Old Value) × 100. When to use: Measuring growth or decline over time. Real example: Your weight was 80kg, now 68kg. What's the percentage loss? ((68 - 80) ÷ 80) × 100 = -15% (loss). Pro Tip: Negative result = decrease. Positive = increase. The "old value" is your baseline.

3⃣ Find the Original Value (Reverse Percentage

Original = Final Value ÷ (1 + Percentage/100). When to use: Working backwards from a percentage. "If something is 20% off, what was the original price?". Real example: A jacket costs ₹800 after 20% discount. What was original price? Original = 800 ÷ (1 - 0.20) = 800 ÷ 0.80 = ₹1,000. Pro Tip: For discount (use minus). For markup/increase (use plus).

4⃣ Format Conversions (% ↔ Fraction ↔ Decimal

PERCENTAGE TO DECIMAL. ÷ 100. 50% ÷ 100 = 0.5. DECIMAL TO PERCENTAGE. × 100. 0.5 × 100 = 50%. FRACTION TO PERCENTAGE. ÷ then × 100. 1/4 = 0.25 = 25%. Scenario: A product costs ₹100 with a 40% discount. What's the final price in all formats?. As percentage: Discount = 40%, Final = 60% of original. As fraction: Discount = 2/5, Final = 3/5 of original. As decimal: Discount = 0.40, Final = 0.60 × ₹100 = ₹60. All three express the same reality—pick the format that works for your use case!.

Calculate Discount While Shopping

Situation: You see a shirt originally ₹2000 with 35% off. What's the final price?. Steps:. • Select "What is X% of Y?". • Enter 35 (discount %) and 2000 (original price). • Get ₹700 discount amount. • Final price: ₹2000 - ₹700 = ₹1300. Pro Tip: Use "What % of Total?" to reverse-check: ₹700 discount is what % of ₹2000? Answer: 35%. Matches the tag.

Evaluate Salary Increase Offer

Situation: Your current salary is ₹50,000/month. Employer offers ₹58,500/month. What % increase is that?. Steps:. • Select "Percentage Increase". • Enter 50000 (original) and 58500 (new). • Get 17% salary increase. • Monthly gain: ₹8,500 | Annual gain: ₹1,02,000. Decision: Is 17% increase in line with inflation (typically 5-7%)? Yes, it's above inflation. Plus, ₹1 lakh annual gain is significant. Likely worth negotiating for.

Calculate Investment Returns

Situation: You invested ₹1,00,000 in a mutual fund. After 1 year, it's worth ₹1,12,000. What's your return percentage?. Steps:. • Select "Percentage Increase". • Enter 100000 (original) and 112000 (new value). • Get 12% return. • Profit: ₹12,000 in 1 year. Analysis: 12% annual return is solid (stock market average is 10-12%). If this continues for 3 years, your ₹1 lakh becomes ₹1,40,493 (compound growth).

Calculate GST (India Taxes

Situation: You're buying an electronics item (18% GST). Price before tax: ₹10,000. Total cost?. Steps:. • Select "What is X% of Y?". • Enter 18 (GST %) and 10000 (base price). • Get ₹1,800 GST amount. • Final price: ₹10,000 + ₹1,800 = ₹11,800. Note: Different GST rates apply: 0% (food), 5% (books), 12% (clothes), 18% (electronics), 28% (luxury). Always verify the applicable rate for your purchase.

Convert Exam Score to Percentage

Situation: You scored 92 marks out of 120 on your exam. What's your percentage score?. Steps:. • Select "What % of Total?". • Enter 92 (marks obtained) and 120 (total marks). • Get 76.67% score. • Grade: Usually A or A+ (depending on institution). Grade Conversion: Most institutions use 70% = A, 80% = A+, 90% = O. Your 76.67% likely qualifies as A grade.

How Percentages Work

The Basic Percentage Formula

Percentage Change — Increase and Decrease

Reverse Percentage Calculations

Quick Mental Math Shortcuts

1. Mixing Up "Percentage Point" vs "Percentage Change"

2. Forgetting the Asymmetry of Increases/Decreases

3. Calculating Discount on Discounted Price

4. Confusing "Of" Language in Percentage

"20% more than 50" vs "20% of 50" are different!. Wrong: "20% more than 50" = 50 (treating it like just 20% of 50). Correct: "20% more than 50" = 50 + (20% of 50) = 50 + 10 = 60.

5. Ignoring Significant Figures

Reporting extreme precision when measurements don't warrant it. Wrong: "Discount is 33.3333333333%" (meaningless precision). Correct: "Discount is approximately 33%" or "33.33%" with 2 decimals max.

Percentage Calculation

How to Use This Calculator

Understanding Your Results

Key Tips

How do I calculate what percentage one number is of another?

What is the formula for percentage increase?

How to calculate percentage decrease?

How to find the original price after a discount?

What is the difference between percentage increase and percentage difference?

How to calculate discount percentage while shopping?

What is GST calculation and how does it differ from discount?

How to calculate percentage increase on salary or investment returns?

How to calculate test score or exam percentage?

What is profit margin vs markup percentage?

How to calculate percentage error in measurements?

What are quick mental tricks to calculate percentages?

How to calculate compound percentage increase over multiple years?

How to calculate percentage growth rate for business or investment?

When should I use percentage vs absolute numbers?

How to calculate weighted percentage average?

What's the difference between percentage point and percentage? How do you calculate it?

How to convert between percentage, fraction, and decimal?

What is a basis point and where is it used?

How do I calculate what percentage different amounts represent when they have different bases?

Why does a 50% decrease require 100% increase to recovery?

How do I calculate percentage for very small values (like interest rates, error margins)?

Related Calculators

Percentage Change Calculator

Percentage Difference Calculator

Age Calculator

Password Generator

Random Number Generator

Annuity Calculator

Combinations & Permutations Calculator

Day Calculator

Debt Payoff Calculator

Discount Calculator

Percentage Calculation

How to Use This Calculator

Understanding Your Results

Key Tips

How Percentages Work

The Basic Percentage Formula

Percentage Change — Increase and Decrease

Reverse Percentage Calculations

Quick Mental Math Shortcuts

1. Mixing Up "Percentage Point" vs "Percentage Change"

2. Forgetting the Asymmetry of Increases/Decreases

3. Calculating Discount on Discounted Price

4. Confusing "Of" Language in Percentage

5. Ignoring Significant Figures

6. Applying Percentage to Already Percentage Values Incorrectly

Golden Rules to Avoid Mistakes:

Why Percentage Calculations Matter

Who Needs This Percentage Calculator?

Percentage Increase Interpretation

Percentage Decrease Caution

1⃣ Basic Percentage Formula

2⃣ Percentage Increase/Decrease Formula

3⃣ Find the Original Value (Reverse Percentage

4⃣ Format Conversions (% ↔ Fraction ↔ Decimal

Calculate Discount While Shopping

Evaluate Salary Increase Offer

Calculate Investment Returns

Calculate GST (India Taxes

Convert Exam Score to Percentage

Example: What is 20% of $1,000?

How Percentages Work

The Basic Percentage Formula

Percentage Change — Increase and Decrease

Reverse Percentage Calculations

Quick Mental Math Shortcuts

1. Mixing Up "Percentage Point" vs "Percentage Change"

2. Forgetting the Asymmetry of Increases/Decreases

3. Calculating Discount on Discounted Price

4. Confusing "Of" Language in Percentage

5. Ignoring Significant Figures

6. Applying Percentage to Already Percentage Values Incorrectly

Golden Rules to Avoid Mistakes:

Why Percentage Calculations Matter