Ratio Calculator — Solve, Simplify, and Scale Ratios
Calculate equivalent ratios, simplify fractions, solve proportions, and scale recipes or maps. Free ratio calculator for math, cooking, and construction.
Ratios show up everywhere — recipes, maps, screen resolutions, mixing concrete, diluting chemicals, and every proportion problem in school math. The CalcHub Ratio Calculator solves, simplifies, and scales ratios instantly.
Ratio Operations
Simplify a Ratio
Divide both parts by their greatest common divisor (GCD):| Original | GCD | Simplified |
|---|---|---|
| 12:8 | 4 | 3:2 |
| 15:25 | 5 | 3:5 |
| 100:250 | 50 | 2:5 |
| 36:48 | 12 | 3:4 |
| 9:12:15 | 3 | 3:4:5 |
Solve for Missing Value (Proportion)
If A:B = C:D and you know three values, find the fourth: A/B = C/D → D = B × C / A| Known Ratio | Scale To | Answer |
|---|---|---|
| 2:3 = 10:? | 15 | |
| 5:8 = ?:24 | 15 | |
| 3:7 = 12:? | 28 | |
| 1:4 = ?:100 | 25 |
Scale a Ratio
Multiply both parts by the same number:| Base Ratio | × 2 | × 3 | × 5 | × 10 |
|---|---|---|---|---|
| 1:2 | 2:4 | 3:6 | 5:10 | 10:20 |
| 2:3 | 4:6 | 6:9 | 10:15 | 20:30 |
| 3:4 | 6:8 | 9:12 | 15:20 | 30:40 |
Practical Applications
Cooking / Recipe Scaling
A recipe serves 4 with 2 cups flour, 3 eggs, 1 cup sugar. For 10 servings:Scale factor = 10/4 = 2.5
| Ingredient | Original (4 servings) | Scaled (10 servings) |
|---|---|---|
| Flour | 2 cups | 5 cups |
| Eggs | 3 | 7.5 → 8 eggs |
| Sugar | 1 cup | 2.5 cups |
| Butter | 100g | 250g |
Mixing and Dilution
Concrete mix ratio is typically 1:2:3 (cement:sand:gravel).For 1 cubic meter of concrete (total parts = 6):
- Cement: 1/6 × 1 m³ ≈ 0.167 m³ ≈ 7 bags (50kg)
- Sand: 2/6 × 1 m³ ≈ 0.333 m³
- Gravel: 3/6 × 1 m³ ≈ 0.500 m³
Screen Resolutions and Aspect Ratios
| Resolution | Ratio | Common Name |
|---|---|---|
| 1920 × 1080 | 16:9 | Full HD |
| 2560 × 1440 | 16:9 | 2K / QHD |
| 3840 × 2160 | 16:9 | 4K / UHD |
| 2560 × 1080 | 21:9 | Ultrawide |
| 1080 × 1080 | 1:1 | Instagram square |
| 1080 × 1920 | 9:16 | Instagram Reels / TikTok |
| 1024 × 768 | 4:3 | Old monitors |
Maps and Scale
Map scale 1:50,000 means 1 cm on the map = 50,000 cm (500 m) in reality.| Map Distance | Scale 1:25,000 | Scale 1:50,000 | Scale 1:100,000 |
|---|---|---|---|
| 1 cm | 250 m | 500 m | 1 km |
| 2 cm | 500 m | 1 km | 2 km |
| 5 cm | 1.25 km | 2.5 km | 5 km |
| 10 cm | 2.5 km | 5 km | 10 km |
Financial Ratios
| Ratio | Formula | Good Range |
|---|---|---|
| Debt-to-income | Total debt / Gross income | Below 0.36 (36%) |
| Price-to-earnings (P/E) | Stock price / Earnings per share | 15–25 (varies by sector) |
| Current ratio | Current assets / Current liabilities | 1.5–3.0 |
| Expense ratio | Annual expenses / Fund assets | Below 1% (below 0.5% ideal) |
How to Use the Calculator
- Open the CalcHub Ratio Calculator
- Enter the ratio values (e.g., 12:8 or 3:4 = ?:20)
- Choose operation: simplify, solve proportion, or scale
- See the result instantly
What's the difference between a ratio and a fraction?
A ratio compares two quantities (3:4 means "3 to 4"). A fraction represents a part of a whole (3/4 means "3 out of 4"). They're related: the ratio 3:4 means the first quantity is 3/7 of the total and the second is 4/7. In calculation, a:b can be written as a/b.
Can ratios have more than two parts?
Yes — 1:2:3 (cement:sand:gravel) is a three-part ratio. To find each component's share, add all parts (1+2+3=6) and divide: cement is 1/6, sand is 2/6, gravel is 3/6.
How do I convert a ratio to a percentage?
Divide each part by the total of all parts, then multiply by 100. For 3:2: total = 5. First part = 3/5 × 100 = 60%. Second part = 2/5 × 100 = 40%.
Related Calculators
- Percentage Calculator — convert ratios to percentages
- Fraction Calculator — fraction arithmetic
- Golden Ratio Calculator — the 1:1.618 ratio
- Aspect Ratio Calculator — screen and image ratios