Ratio Calculator
Simplify ratios to whole numbers or solve a proportion A : B = C : X.
Runs in your browser — nothing is uploadedEnter values
Calculate
Result
- As 1 : n
- 1 : 1.5
- As n : 1
- 0.6667 : 1
- A as % of total
- 40%
How it's calculated
Divide both sides by their greatest common divisor
12 : 18 = 2 : 3
About Ratio Calculator
A ratio compares two quantities, such as 3:2 for a mix of ingredients or 16:9 for a screen. This calculator simplifies a ratio to its smallest whole numbers and solves proportions of the form A : B = C : X, where you need the missing value.
It is a quick way to scale recipes, mix materials, resize images without distortion and work out shares.
When to use it
- Scaling recipes up or down for more or fewer people.
- Mixing concrete, paint, fertiliser or cleaning solutions.
- Keeping the aspect ratio when resizing images or video.
- Dividing money or work in a fixed proportion.
Tips for better results
- Make sure both parts use the same unit before comparing them.
- For aspect ratios, solve width : height = new width : X to find the new height.
- A simplified ratio makes comparisons easier — 1920:1080 simplifies to 16:9.
How to use the Ratio Calculator
- Choose simplify or solve.
- Enter the ratio values.
- See the simplified ratio or the missing value.
Frequently asked questions
How do you simplify a ratio?
Divide both parts by their greatest common divisor. 12:18 ÷ 6 = 2:3. Decimal ratios are scaled to whole numbers first, so 1.5:2.5 becomes 3:5.
How do I solve A:B = C:X?
X = B × C ÷ A. For 2:3 = 10:X, X = 3 × 10 ÷ 2 = 15.
Can ratios contain decimals?
Yes. The calculator converts decimal ratios into the equivalent whole-number ratio when simplifying, for example 1.5:2 becomes 3:4.
How do I split an amount in a ratio?
Add the parts of the ratio, divide the amount by that total, then multiply by each part. For 300 in the ratio 1:2, each part is 100, so the shares are 100 and 200.