Notification
Go to Home All Tools Compare Glossary Blog Contact

Ratio Calculator

Solve missing ratio values, simplify ratios to their lowest terms, scale aspect ratios like 16:9, or split an amount by ratio.

Form: A : B = C : X
15.00

Standard Aspect Ratios & Resolutions

16:9 Widescreen 1920×1080 (FHD), 2560×1440 (2K QHD)
4:3 Standard 1024×768, Photo prints, iPad displays
21:9 Ultrawide 3440×1440 Cinematic & Gaming Monitors
1:1 Square 1080×1080 Instagram Posts & Avatars

Calculated Solution

Proportion Answer X = 15.00
Visual Distribution

Ratio Formulas Cheat Sheet

Proportion X = (B × C) / A
Simplification Term / GCD(A, B, C)
Aspect Height H₂ = W₂ × (H₁ / W₁)
Part Share Total × (Part / ∑Parts)
Mathematical Guide

Mastering Ratios, Proportions & Scale Factors

Fundamental mathematical relationships to solve proportions, simplify multi-part terms, scale visual aspect ratios, and partition monetary amounts:

1

What is a Ratio?

A ratio compares the relative sizes of two or more values. Expressed as A:B, A/B, or "A to B", it indicates how many times one number contains another.

2

What is a Proportion?

A proportion states two ratios are equal (A:B = C:D). When 3 values are known, target X is computed via cross-multiplication: X = (B × C) ÷ A.

3

Simplification & GCD

Ratios simplify by dividing all terms by their Greatest Common Divisor (GCD). E.g., 12:18:24 simplifies to 2:3:4 when divided by 6.

Step-by-Step Practical Calculations

Example 1: Solving 2:3 = 10:X Cross-Multiplication
  1. Write as fractions: 2 ÷ 3 = 10 ÷ X
  2. Cross-multiply terms: 2 × X = 3 × 10 = 30
  3. Solve for target: X = 30 ÷ 2 = 15
Example 2: Dividing $1,000 in Ratio 2:3:5 Proportional Split
  1. Sum parts: 2 + 3 + 5 = 10 total parts
  2. Value per part: $1,000 ÷ 10 = $100
  3. Calculate shares: 2×$100 = $200, 3×$100 = $300, 5×$100 = $500
Daily Usage

Real-World Practical Applications

🍳

Culinary & Baking

Scale recipe quantities proportionally when modifying batch yields without disturbing flavor balance.

📐

Architecture & Maps

Convert blueprint scale ratios (e.g. 1:50, 1:100) into actual building measurements accurately.

🖥️

Digital Video & Display

Maintain 16:9, 4:3, or 21:9 image and monitor aspect ratios to avoid stretching or letterboxing distortion.

📈

Business Finance

Evaluate leverage metrics like Debt-to-Equity (D/E), equity partnership splits, and profit margins.

Mathematics

AI Ratio & Proportion Advisor

Ask AI
Education

How Ratio Calculations Work

01

Solving a Ratio Proportion

A proportion A:B = C:X is solved by cross-multiplication: A x X = B x C, so X = (B x C) / A. For example, in 2:3 = 10:X, X = (3 x 10) / 2 = 15.

02

Simplifying a Ratio with the GCD

A ratio is simplified to its lowest terms by dividing every term by their greatest common divisor (GCD). The ratio 4:6 has a GCD of 2, so it simplifies to 2:3, and this same GCD method extends to three-term ratios such as 4:6:8, which simplifies to 2:3:4.

03

Dividing an Amount by a Ratio

To split a total amount by a ratio such as 2:3:5, add the parts together (2 + 3 + 5 = 10 parts) and divide the total by that sum to find the value of one part. For a total of 1,000 split 2:3:5, one part equals 100, giving shares of 200, 300, and 500.

04

When to Use Related Math Tools

Use the Fraction Calculator when a ratio needs to be added to or compared against a fraction, and the LCM & HCF Calculator when you need the underlying common divisor or multiple used to simplify or scale a ratio.

Good to know

Questions, answered

Quick answers about how this tool works.

Use cross-multiplication: A × X = B × C, so X = (B × C) ÷ A. For example, in 2:3 = 10:X, X = (3 × 10) ÷ 2 = 15.

Add the ratio parts (2 + 3 + 5 = 10 parts). Divide the total amount by 10 to find 1 part value, then multiply each ratio number by the 1 part value.

A ratio compares the relative sizes of two or more values. To simplify a ratio, divide all numbers by their greatest common divisor (GCD). For example, 15:20 simplifies to 3:4.

Sum the parts of the ratio to get the total parts. Divide the number by the total parts to find the value of one part, then multiply by each ratio term.

What do you need to work out next?

Search 244+ free tools by name, or pick a category below. Every one runs instantly in your browser — no signup, nothing to install.