Ratio Calculator
Simplify an aspect ratio, solve a proportion, or scale a named recipe in one live calculator — no calculate button needed.
- Fewer clicks, keyboard friendly
- Features others lock behind paywalls
Simplify a screen ratio, solve one missing proportion, or scale a named recipe as you type.
Saved in this browserCalculation
Simplify a width and height
1,920 : 1,080 = 16 : 9
Calculations happen in this browser. Your values are saved only on this device.
How to use
- Choose Screen ratio to reduce a width and height, then optionally enter a target width for its matching height.
- Choose Proportion and leave one of a, b, c, or d blank to solve a : b = c : d.
- Choose Recipe, enter the original and target servings, and name up to three ingredients.
- Read the result and equation as each value updates, then copy a simplified ratio when needed.
How a ratio becomes 16:9
To simplify two whole-number dimensions, divide both numbers by their greatest common divisor (GCD). A 1,920 × 1,080 image has a GCD of 120, so 1,920 : 1,080 becomes 16 : 9. The same operation works for values with up to 9 decimal places after they are put on a shared decimal scale: 1.5 : 2.25 becomes 150 : 225, then 2 : 3. A ratio such as 16:9 is a relationship, not a size: 1,280 × 720 and 3,840 × 2,160 have the same 16:9 aspect ratio.
Solving a proportion with cross multiplication
For a : b = c : d, equal ratios have equal cross-products: a × d = b × c. If 3 : 4 = 6 : d, d is (4 × 6) ÷ 3 = 8. The order matters: in the usual fraction form, a/b = c/d, so b and d cannot be zero when you evaluate the ratios. Some zero-filled equations have no answer or infinitely many answers; the calculator identifies those instead of choosing a misleading number.
Scaling every recipe ingredient by the same factor
Recipe scaling uses target servings ÷ original servings as one multiplier for every ingredient. To turn a 4-serving recipe into 6 servings, the factor is 6 ÷ 4 = 1.5; 300 g of flour becomes 450 g and 2 eggs become 3. The calculation preserves proportions, but it cannot account for pans, cooking time, seasoning, or ingredient quantities that need practical rounding. Treat its numbers as a starting point for a recipe, not a food-safety instruction.
Frequently asked questions
How do I simplify a ratio?
Divide both terms by their greatest common divisor. For example, 1,920:1,080 simplifies by dividing both terms by 120, giving 16:9. If the terms contain decimals, first put them on the same decimal scale: 1.5:2.25 is 150:225, then 2:3.
How do I find a missing value in a proportion?
Use cross multiplication. In a:b = c:d, a × d equals b × c. For 3:4 = 6:x, x is 4 × 6 ÷ 3 = 8. Leave exactly one field blank in the proportion calculator to apply this formula.
How do I calculate the height for a 16:9 width?
Divide the width by 16 and multiply by 9. For a 1,920-pixel-wide 16:9 image, the height is 1,920 ÷ 16 × 9 = 1,080 pixels. The Screen ratio calculator performs this for any positive width and height relationship.
How do I scale a recipe from 4 servings to 6?
Multiply every ingredient by 6 ÷ 4, or 1.5. For example, 300 g becomes 450 g and 2 cups become 3 cups. The same factor keeps all three ingredient proportions unchanged.
Can a ratio contain zero?
A ratio can have one zero term, such as 0:5, which simplifies to 0:1. The ratio 0:0 has no value because it cannot compare two quantities. A proportion with a zero denominator can also have no solution or more than one solution.
Does this ratio calculator send my values to a server?
No. Simplification, proportion solving, and recipe scaling run in the browser. Values are stored only in that browser so they remain after a refresh and are not sent to a server.
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Updated 2026-10-29