Percentage Calculator
The complete toolkit for all your percentage calculations
Difference %
Calculate the difference between two numbers in percentage.
📐 See formulaExample: Between 100 and 120 = 20%
Variation %
Calculate the variation between a number and a percentage.
📐 See formulaExample : 100 ±10% = 110 or 90
Simple variation
Value in %
Coefficient ×
Before addition
Before discount
Addition %
Deduction %
💡 Calculations with VAT Included or without VAT
🔢 Pre-tax → Tax-inclusive
100€ Ex. VAT + 10% of taxes = 110€ Inc. VAT
+10% of taxes of 100€ Ex. VAT = 10€ of taxes
🔢 Tax-inclusive → Pre-tax
110€ Inc. VAT with 10% of taxes = 100€ Ex. VAT
110€ Inc. VAT - 100€ Ex. VAT = 10€ of taxes
🏷️ Practical discount calculation examples
🔻 Apply a discount
150€ - 20% of discount = 120€
discount of 20% on 150€ = 30€ of savings
You save 30€ thanks to this discount
🔍 Find the original price
120€ after 20% of discount = 150€ original price
original price 150€ - 30€ discount = 120€
The discount was 30€
🎯 Cascade discounts (example)
Initial price
200€
1st discount (-30%)
140€
(-60€)
2nd discount (-10%)
126€
(-14€)
💡 Total savings : 74€ (37% of initial price)
📝 Remember : Cascade discounts don't add up! A 30% then 10% discount ≠ 40% total discount. Each discount applies to the already reduced price.
⚡ SLA (Service Level Agreement) calculation examples
✅ Calculate uptime
8736h uptime / 8760h total = 99.73% availability
Downtime : 24h (0.27%)
Good SLA level, satisfactory availability
⏱️ Allowed downtime
8760h total period × 0.1% Allowed downtime = 8.76h max downtime
max downtime : 526 minutes / 0.4 days
Downtime budget: 8.76h per year
📊 Standard SLA levels (per year)
99%
87.6h/an
Basic
99.9%
8.76h/an
Good
99.99%
52.6min/an
Excellent
99.999%
5.3min/an
Exceptional
🔧 Technical note : SLA measures service availability. The higher the percentage, the less downtime is allowed. A 99.9% SLA only permits 8h45 of downtime per year!
📐 Basic Calculation Formulas
🔢 Percentage Difference
Formula:
|Value2 - Value1| ÷ Value1 × 100
Example:
Difference between 100 and 120 :
|120 - 100| ÷ 100 × 100 = 20%
|120 - 100| ÷ 100 × 100 = 20%
Use case: Compare prices, performance, statistics
📊 Variation with %
Formula:
Number × (Percentage ÷ 100)
Example:
±10% on 100 :
• Increase: 100 + (100 × 10/100) = 110
• Decrease: 100 - (100 × 10/100) = 90
• Increase: 100 + (100 × 10/100) = 110
• Decrease: 100 - (100 × 10/100) = 90
Use case: Quick increase/decrease calculations
📈 Rate of Change
Formula:
(Final value - Initial value) ÷ Initial value × 100
Example:
From 200 to 250 :
(250 - 200) ÷ 200 × 100 = +25%
(250 - 200) ÷ 200 × 100 = +25%
Use case: Sales evolution, performance
🎯 Value as %
Formula:
Part ÷ Total × 100
Example:
100 = what % of 1000 ?
100 ÷ 1000 × 100 = 10%
100 ÷ 1000 × 100 = 10%
Use case: Market shares, proportions
✖️ Multiplier Coefficient
Formula:
Value2 ÷ Value1
Example:
100 ÷ 50 = 2
Verification : 50 × 2 = 100 ✓
Verification : 50 × 2 = 100 ✓
Use case: Proportionality, scales, ratios
🎓 Advanced Formulas
🔍 Price Before Discount
Formula:
Discounted price ÷ (1 - Percentage/100)
Example:
$90 after -10% discount :
90 ÷ (1 - 10/100) = 90 ÷ 0.9 = $100
90 ÷ (1 - 10/100) = 90 ÷ 0.9 = $100
Use case: Find prices before sales
🔙 Value Before Increase
Formula:
Final value ÷ (1 + Percentage/100)
Example:
$110 after +10% :
110 ÷ (1 + 10/100) = 110 ÷ 1.1 = $100
110 ÷ (1 + 10/100) = 110 ÷ 1.1 = $100
Use case: Tax-incl → Pre-tax
➕ Add a %
Formula:
Value × (1 + Percentage/100)
Example:
$100 + 20% :
100 × (1 + 20/100) = 100 × 1.2 = $120
100 × (1 + 20/100) = 100 × 1.2 = $120
Use case: Tax-inclusive price, markup
➖ Deduct a %
Formula:
Value × (1 - Percentage/100)
Example:
$100 - 20% :
100 × (1 - 20/100) = 100 × 0.8 = $80
100 × (1 - 20/100) = 100 × 0.8 = $80
Use case: Discounts, sale prices
Professional calculator - All your percentage calculations in one click