Master ratio calculations with our comprehensive GCSE Maths tool. Convert between ratios, fractions, and percentages with detailed working.
Simplify a ratio to its lowest terms
Ratios are simplified by dividing both parts by their greatest common divisor (GCD). This reduces the ratio to its simplest form while maintaining the same proportions.
Reduce ratios to their simplest form using the greatest common divisor
Divide both parts by their GCDExample: 8:12 ÷ 4 = 2:3
Convert ratio parts to fractions of the whole
Part ÷ Total = FractionExample: 3:7 → 3/10 and 7/10
Convert ratio parts to percentages
(Part ÷ Total) × 100 = PercentageExample: 3:7 → 30% and 70%
Multiply or divide ratios to reach a target sum
Ratio × (Target Sum ÷ Current Sum)Example: 2:3 scaled to sum 50 = 20:30
Divide each part by the total to get fractions.
Convert fractions to percentages by multiplying by 100.
Multiply both parts by the same number to scale.
Example: A ratio of 2:3 needs a total of 50 parts.
Current sum = 2 + 3 = 5
Multiplier = 50 ÷ 5 = 10
Scaled ratio = 2 × 10 : 3 × 10 = 20:30
Answer: 20:30
Example: Ratio 2:3, first part is 20.
Multiplier = 20 ÷ 2 = 10
Second part = 3 × 10 = 30
Answer: 20:30
Get step-by-step explanations and practice questions with our Maths Genie.