Ratio Calculator for Simplifying, Solving, and Converting
This ratio calculator helps you simplify ratios, solve a proportion for a missing value, convert a ratio to a fraction or percentage, and split an amount by ratio. It is built for students checking homework, cooks scaling recipes, and anyone who works with ratios at work or at home.
Pick one of four tabs — Simplify Ratio, Proportion Solver, Convert, or Divide by Ratio — and the answer updates the moment you type. Every step uses standard math: greatest common divisor for simplifying and cross multiplication for solving proportions.
How to Calculate a Ratio
Simplify a ratio
On the Simplify Ratio tab, enter the two numbers (for example 12 and 18). The reduced ratio appears at once — 2 : 3 — and the details panel shows the original ratio, the GCD used, and the simplified result. Use Swap to flip the two sides or Clear to start over.
Solve a proportion for x
Open the Proportion Solver tab and fill three of the four boxes in A : B = C : D. Leave the unknown box empty and it is solved instantly, highlighted, and shown with the cross-multiplication formula A × D = B × C. Fill all four boxes and the tool tells you whether the proportion is valid.
Convert a ratio
On the Convert tab, type a ratio such as 3 : 4 to see it as a fraction, a decimal, a percentage split, and a parts-of-total description — all at the same time. Swap or clear the inputs whenever you need.
Divide an amount by ratio
Use the Divide by Ratio tab to split a total. Enter the total amount (say 100) and the ratio parts (such as 2 : 3 : 5). Use the plus and minus buttons to set anywhere from 2 to 10 parts, then read each part's value plus a total-check sum that confirms the split adds back up.
Features
Ratio Simplifier
Reduce any ratio to its lowest terms using the greatest common divisor, with the original, GCD, and simplified values shown side by side.
Proportion Solver
Find the missing value in A : B = C : D by cross multiplication. Solve for any position, see the formula, and validate the proportion when all four values are filled.
Multi-Format Conversion
Turn one ratio into a fraction, a decimal, a percentage split, and a parts-of-total description at the same time.
Flexible Ratio Division
Split any total across 2 to 10 ratio parts, add or remove parts on the fly, and confirm the result with an automatic total check.
Swap & Clear
Reverse the two sides of a ratio with one tap, or clear every input and result to begin a fresh calculation.
Tabbed, Real-Time Interface
Four focused tabs recalculate as you type, work on phones, tablets, and desktops, and include a built-in dark mode.
Frequently Asked Questions
How do I calculate a ratio between two numbers?
Enter both numbers on the Simplify Ratio tab. The calculator divides each by their greatest common divisor and shows the ratio in its lowest terms. For example, 12 and 18 become 2 : 3 because the GCD is 6.
How do I solve a proportion for x?
On the Proportion Solver tab, type the three known values into A : B = C : D and leave the unknown box empty. The missing value is solved automatically and highlighted. For 2 : 4 = 3 : ?, the answer is 6.
What is cross multiplication?
Cross multiplication is the rule that, in a proportion A : B = C : D, the products of the diagonal terms are equal: A × D = B × C. The Proportion Solver uses this rule to find any single missing value, and it displays the equation so you can follow the math.
What is the GCD and why is it shown?
The GCD (greatest common divisor) is the largest number that divides both parts of a ratio evenly. It tells you how much the ratio was reduced. For 12 : 18 the GCD is 6, so dividing both by 6 gives the simplified 2 : 3.
What is the difference between a ratio and a proportion?
A ratio compares two quantities, such as 2 : 3. A proportion states that two ratios are equal, such as 2 : 3 = 4 : 6. Use the Simplify and Convert tabs for ratios, and the Proportion Solver tab when two ratios must match.
How do I scale a recipe using ratios?
Treat the original amount and the target amount as a proportion. For example, to scale a recipe written for 2 servings up to 5, solve 2 : 1 = 5 : ? on the Proportion Solver tab to find the multiplier, or use Divide by Ratio to split a batch into the portions you need.
Can I use decimal numbers?
Yes. Every input accepts decimals, and results are shown with sensible precision. Division by zero is handled safely, so an invalid input simply shows no result instead of an error.
How many parts can I divide an amount into?
The Divide by Ratio tab supports 2 to 10 parts. Use the plus and minus buttons to add or remove parts; the total-check sum confirms the divided values add back up to the original amount.
Is my data saved or sent anywhere?
No. Every calculation happens locally in your browser. Nothing you enter is stored or sent to a server, and the tool works on phones, tablets, and desktops alike.
No comments yet. Be the first to comment!