Fractions to percentages is one of those skills you’ll use forever — on tests, in shopping discounts, and anywhere numbers show up. The good news: it takes exactly three steps, and the same three steps work every single time.
Step 1 — Divide the Top by the Bottom
Take the top number of the fraction (the numerator) and divide it by the bottom number (the denominator). For 15/20: 15 ÷ 20 = 0.75.
Step 2 — Multiply by 100
Take your answer from Step 1 and multiply it by 100. For our example: 0.75 × 100 = 75.
Step 3 — Add the Percent Sign
Put a % sign after your answer. Done: 15/20 = 75%.
Worked Examples
- 3/4 → 3 ÷ 4 = 0.75 → × 100 = 75%
- 7/10 → 7 ÷ 10 = 0.7 → × 100 = 70%
- 11/15 → 11 ÷ 15 ≈ 0.733 → × 100 ≈ 73.3%
- 30/2000 → 30 ÷ 2000 = 0.015 → × 100 = 1.5%
Common Fractions Cheat Sheet
Memorize these and you’ll rarely need the steps: 1/2 = 50%, 1/3 ≈ 33.3%, 1/4 = 25%, 3/4 = 75%, 1/5 = 20%, 2/5 = 40%, 1/10 = 10%.
Why This Matters for Grades
Test scores are almost always fractions (15 out of 20), but report cards speak in percentages and letter grades. Converting between the two is how you translate “I got 15 right” into “I got a C.”
Skip the Math — Use the Calculator
Want the answer without the arithmetic? Try our 15-out-of-20 calculator — it converts any score instantly and shows the letter grade too.
Frequently Asked Questions
How do you work out a percentage from a fraction?
Divide the top number (the numerator) by the bottom number (the denominator), multiply the result by 100, and add the % sign. For example, 3/4 → 3 ÷ 4 = 0.75 → 0.75 × 100 = 75%. Finding a percent from a fraction is always these same three steps, whatever the numbers are.
How do I change a fraction to a percentage?
To change a fraction to a percent, use the same method: divide, multiply by 100, add the sign. So 5/8 → 5 ÷ 8 = 0.625 → 62.5%. If the division leaves a long decimal, two decimal places is plenty for almost every real-world answer.
Try Our Free Calculators
Put this guide into practice with our free tools: Percentage Calculator, Fraction To Decimal Calculator.