Percentage Calculator

How to use the Percentage Calculator

1. Enter a percentage
   In Percentage (%), type the rate you want to apply (e.g. 15 for 15%).
2. Enter the base value
   In Of value, type the number you want to take the percentage of (e.g. 120).
3. Calculate
   Click Calculate. The result shows X% of Y with a clear answer you can copy.
4. Reset
   Click Clear to start a new calculation.

What you can do

• Find X% of Y: “What is 18% of 250?” → enter 18 and 250.
• Work out discounts: “20% off £79.99” → 20% of 79.99 = amount off; subtract from the original price.
• VAT add/remove (quick method): VAT 20% on £50 → 20% of 50 = 10, final = £60. Reverse VAT 20% from £60 → net = 60 / 1.20 = 50.
• Tips/Service: “12.5% tip on £48” → 12.5% of 48 = £6.00.
• Grades & marks: “You scored 37 out of 45” → percent = (37/45) × 100 = 82.22%.
• Simple growth/decline checks: Use the change formulas below to check % increase or % decrease between two values.

Handy formulas (copy & use)

• X% of Y → (X ÷ 100) × Y
• % increase (from A to B) → ((B − A) ÷ A) × 100
• % decrease (from A to B) → ((A − B) ÷ A) × 100
• Find the base when you know the part and % → Base = Part ÷ (X ÷ 100)

Quick examples

• 15% of 120 → 0.15 × 120 = 18 (answer: 18)
• Price after 30% discount on £80 → 30% of 80 = 24 → £80 − £24 = £56
• % increase from 50 to 65 → ((65−50)/50)×100 = 30%
• % decrease from 90 to 72 → ((90−72)/90)×100 = 20%

Best practices

• For money, round to 2 decimals to match receipts and invoices.
• For grades or reports, show 1–2 decimals for clarity (e.g., 82.2%).
• When reversing tax or markup, divide by (1 + rate) (e.g., 20% → divide by 1.20).

Troubleshooting

• Result looks off? Ensure the percent is entered as a number (type 15, not 0.15).
• Need a whole number? Round or use the nearest integer after calculating.
• Comparing two values? Use the % increase/decrease formulas above for accurate change.

Tip: If a store shows “Price including 20% VAT: £120”, the net price is 120 / 1.20 = £100 and the VAT part is £20.