See the relationship.
Turn 150 : 100 into 3 : 2. Useful for comparing quantities without the extra zeros.
MYRATIOTABLE · BY ROOF & RATIO
Free ratio calculator.
A lot more clarity.
Simplify ratios, find a missing value, scale a recipe, or split a cost. Everyday math, made simple.
YOUR NUMBERS, IN BALANCE
Ratio calculator
Make your ratio simpler.
Enter two numbers to find their smallest whole-number ratio.
SMALL CALCULATIONS. USEFUL ANSWERS.
Built for the everyday “how much?”
Make enough for everyone.
A recipe needs 2 cups for 4 servings. For 10 servings, you need 5 cups.
Share the cost fairly.
Split a $500 expense in a 3 : 2 ratio: one share is $300 and the other is $200.
THE MATH BEHIND YOUR ANSWER
How to calculate ratios and proportions
A ratio compares two quantities in order. In a 3 : 2 ratio, the first quantity has three parts for every two parts of the second. MyRatioTable handles four everyday uses of that relationship, with the calculation shown alongside your answer.
How to simplify a ratio
Divide both numbers by their greatest common divisor. For 150 : 100, the greatest common divisor is 50. Dividing both numbers by 50 gives 3 : 2. The quantities become smaller, but their relationship stays the same.
Decimals work too: multiply both sides of 1.5 : 0.75 by 100 to get 150 : 75, then simplify to 2 : 1. Keep the order of your quantities and use the same units before comparing them. For example, convert 1 foot and 6 inches to 12 inches and 6 inches first: the ratio is 2 : 1.
Find a missing value in a proportion
Equivalent ratios describe the same relationship. If A : B = C : X, calculate the missing value with X = B × C ÷ A. In 3 : 2 = 12 : X, X = 2 × 12 ÷ 3 = 8.
You can check the answer by multiplying across: 3 × 8 and 2 × 12 both equal 24. In the calculator, choose “Find a missing value” and enter A, B and C. A and B must be greater than zero; C may be zero.
Scale a recipe or quantity
Use new quantity = original quantity × new batch size ÷ original batch size. If 4 servings need 2 cups of rice, 10 servings need 2 × 10 ÷ 4 = 5 cups. Halving the recipe would use 1 cup for 2 servings.
Choose “Scale a quantity,” then enter the ingredient amount, original servings and desired servings. Repeat for each ingredient, keeping its original unit. This tool scales one ingredient at a time. Cooking times and temperatures do not necessarily scale with serving size, and it does not convert cups to grams.
Split a cost in a ratio
Add the ratio parts, then divide the total by that sum. For a $500 cost split 3 : 2, there are 5 parts. Each part is $100, so the shares are $300 and $200. A 3 : 2 split is also a 60% / 40% split.
For a shared household expense, a 1 : 1 ratio splits the total evenly. A 2 : 1 ratio assigns twice as much to the first person. Enter the ratio you have agreed to use; the calculator computes the amounts. Results are rounded to cents, with any remainder assigned to the second share so the amounts add up to your total.
Equivalent ratio table: 3 : 2
Multiply both sides by the same positive number to create an equivalent ratio. Adding the same amount to both sides does not usually preserve the relationship. Every row below simplifies to 3 : 2.
| Multiplier | First quantity | Second quantity | Equivalent ratio |
|---|---|---|---|
| × 1 | 3 | 2 | 3 : 2 |
| × 2 | 6 | 4 | 6 : 4 |
| × 3 | 9 | 6 | 9 : 6 |
| × 4 | 12 | 8 | 12 : 8 |
| × 5 | 15 | 10 | 15 : 10 |
| × 10 | 30 | 20 | 30 : 20 |
| × 20 | 60 | 40 | 60 : 40 |
| × 50 | 150 | 100 | 150 : 100 |
To create another pair, use the missing-value calculator: enter the first two numbers of your ratio and your new first quantity. It returns the matching second quantity.
Ratio to percentage: part-to-part or part-to-whole?
For a ratio A : B, the first part’s share of the total is A ÷ (A + B) × 100%. The second part’s share is B ÷ (A + B) × 100%. A 3 : 2 ratio is therefore 60% and 40% of the whole.
This differs from asking “What percentage is A of B?” For 3 and 2, that answer is 3 ÷ 2 × 100% = 150%. The ratio simplifier’s percentage labels refer to each part’s share of the total.
FROM THE MAKER OF ROOF & RATIO
Clear numbers.
More confident decisions.
Explore practical digital tools for homeowners, homebuyers, investors, and landlords—created by Marchelle.
A LITTLE MORE CLARITY
Common questions
What is a ratio?
A ratio compares quantities. A ratio of 3 : 2 means there are three parts of the first quantity for every two parts of the second. For example, 3 cups of one ingredient and 2 cups of another.
How do you simplify a ratio?
Divide both numbers by their greatest common divisor. For 150 : 100, divide both by 50 to get 3 : 2. For decimals, the calculator first converts both values to whole numbers using the same multiplier.
How does the missing-value calculator work?
For A : B = C : X, the missing value is X = B × C ÷ A. For example, 3 : 2 = 12 : 8. A and B must both be greater than zero.
Can I use decimals or zero?
Yes. Use non-negative numbers up to 1 billion and up to six decimal places. Both parts of a ratio cannot be zero. Cost totals accept two decimal places; cost shares are rounded to cents and always add up to the entered total.
Are my numbers saved or uploaded?
Your calculations run in your browser. This calculator does not upload or store the numbers you enter. Refreshing the page resets the calculator. Copy a result if you want to keep it.
Is this calculator free?
Yes. All four calculator modes are free, with no account required. Roof & Ratio also offers separate free and paid digital products on its store.
About MyRatioTable
MyRatioTable is a free everyday math tool from Roof & Ratio, created by Marchelle Cook. Use it for homework checks, recipe quantities and shared expenses. Calculations run in your browser, and the tool does not upload or save your entered numbers.
For mortgage payment and extra-principal planning, visit our companion MyLoanTable loan calculator. For a calculation question or correction, contact Roof & Ratio.
Guide updated October 6, 2026.