Percentages are everywhere — from shopping discounts to investment returns to business metrics. Our versatile Percentage Calculator handles five common percentage scenarios in one clean interface.
Percentage Calculator
Calculate percentages for any scenario — find what percent one number is of another, or add/subtract a percentage.
How the Percentage Calculator Works
Five calculation modes, one simple tool:
- X% of Y: (X ÷ 100) × Y — Find what X% of a number equals
- X is what % of Y: (X ÷ Y) × 100 — Find the percentage one number is of another
- Percentage change: ((New − Old) ÷ Old) × 100 — Calculate increase or decrease
- Add %: X + (X × Y ÷ 100) — Add a percentage to a number
- Subtract %: X − (X × Y ÷ 100) — Remove a percentage from a number
Worked Example — Two Real-World Uses
Use 1: Calculating a Discount
Scenario
David runs a small online store. A product normally costs $84, and he wants to offer 25% off during a sale.
Inputs
- Original Value: $84
- Percentage: 25%
Calculation Walkthrough
- Convert 25% to a decimal: 25 ÷ 100 = 0.25
- Multiply the original price: $84 × 0.25 = $21
- Subtract: $84 − $21 = $63
Result
- Discount Amount: $21
- Sale Price: $63
Interpretation
A 25% discount saves the customer $21. But David’s revenue drops from $84 to $63 per sale. If his cost is $50, his profit margin at full price is 68% — at the sale price, it drops to 26%. The sale is still profitable, but he needs to sell more units to make the same total profit.
Use 2: Calculating Profit Margin
Inputs: David bought the item for $50 and sells it for $84. What percentage profit is that?
- Part (profit): $34
- Whole (cost): $50
Calculation: 34 ÷ 50 × 100 = 68% profit margin
Practical Advice
- Use the percentage calculator to evaluate discounts before running a sale — check whether the discounted price still covers your costs.
- Calculate the actual dollar amount you will save, not just the percentage off. A 50% discount on a $200 item saves $100, while 25% off a $20 item saves only $5.
- Use the Percentage Change mode to measure growth — for example, sales increased from $5,000 to $6,500 = 30% growth.
💡 Next Decision
If you are a business owner: Before running a sale, enter the original price and discount percentage into the calculator above. Check whether the sale price still covers your costs and leaves room for profit.
If you are a shopper: Use the calculator to find the actual dollar amount you will save. A big percentage on a small item may be less valuable than a small percentage on a big purchase.
If you are tracking change over time: Use the Percentage Change mode to measure your growth — whether it is sales, website traffic, or monthly savings.
Frequently Asked Questions
How do I calculate a 20% tip?
Multiply the bill total by 0.20, or use our Tip Calculator for a more detailed breakdown including split options.
What’s the formula for percentage increase?
((New Value − Original Value) ÷ Original Value) × 100. A positive result means an increase; negative means a decrease.
Pro Tips
- For quick 10% calculations, simply move the decimal point one place left
- Use the “Percentage Change” mode to track investment or sales growth over time
- Double-check by reversing the calculation to verify accuracy