Percentage Calculator
Find a percentage of a number, what percent one number is of another, or the original whole. Three percentage calculations with worked steps.
MYRATIOTABLE · BY ROOF & RATIO
Free Ratio Calculator
& Everyday Math Tools
Simplify ratios, calculate percentages, compare discounts, and solve everyday measurement and time questions. Free tools with clear steps. No signup.
Go straight to the ratio calculator →
EVERYDAY PROBLEMS. CLEAR ANSWERS.
14 free tools, one useful place.
Work out a percentage, compare a sale price, convert a measurement, or count the days. Choose a tool below and get the answer with its steps.
Percent Change Calculator
Calculate percentage increase or decrease between two nonnegative values. See the amount changed, percent change, and formula.
Discount Calculator
Calculate a sale price, savings, optional sales tax, and final total from an original price and percent-off discount.
Length Converter
Convert centimeters to inches, feet to meters, millimeters, kilometers, yards, and miles. See the conversion factor and result.
Area & Square Footage Calculator
Calculate rectangle, triangle, or circle area in square feet, square meters, and your chosen measurement units.
Time Duration Calculator
Calculate hours between two times, subtract break minutes, and handle an end time on the next day. Includes decimal hours.
Days Between Dates Calculator
Count calendar days between two dates, optionally include the end date, and see complete weeks plus remaining days.
Age on a Date Calculator
Find completed years of age and total calendar days from a birth date to a selected date. Includes a clear leap-day convention.
Fraction Calculator
Add, subtract, multiply, or divide two fractions. Get an exact reduced fraction, a decimal approximation, and worked steps.
GCF & LCM Calculator
Find the greatest common factor and least common multiple of two to ten nonnegative whole numbers, with exact integer results.
Ratio Calculator
Simplify two numbers, solve a proportion, scale quantities, or split a cost.
Missing Number Ratio Table
Complete missing values across multiple rows using a known ratio.
Ratio to Percentage
Convert a two-part or three-part ratio to each share of the total.
Three Number Ratio
Reduce all three parts together, including decimal inputs.
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Free · No signupYOUR NUMBERS, IN BALANCE
Ratio calculator
Make your ratio simpler.
Enter two numbers to find their smallest whole-number ratio.
MORE WAYS TO SOLVE
More free ratio calculators
Missing Number Ratio Table Calculator
Fill the gaps in a ratio table. Enter one complete reference row, then the values you know in the other rows. Leave each unknown value blank.
Open calculator →Ratio to Percentage Calculator
Turn a ratio into each part’s percentage of the whole. Enter two parts, or add a third part for a three-way split.
Open calculator →Three Number Ratio Calculator
Simplify all three parts of a ratio together. Enter whole numbers or decimals and keep the same order in the result.
Open calculator →SMALL CALCULATIONS. USEFUL ANSWERS.
Built for the everyday “how much?”
See the relationship.
Turn 150 : 100 into 3 : 2. Useful for comparing quantities without the extra zeros.
Scale your project quantities.
A repeatable project uses 2 boxes for 4 equal sections. For 10 sections, the proportional quantity is 5 boxes.
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.
Ratio simplifier: reduce a ratio to simplest form
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.
Missing-value ratio calculator: solve 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.
Material & project scaling
Use new quantity = original quantity × new project size ÷ original project size. If 4 identical sections need 2 boxes of material, 10 sections need 2 × 10 ÷ 4 = 5 boxes.
Choose “Scale a quantity,” then enter the original material quantity and the two project sizes. Keep both project sizes in the same unit, such as square feet or identical sections. This ratio scaling calculator preserves the original material unit and scales one quantity at a time. Coverage must stay consistent; account separately for waste, packaging and project-specific requirements.
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 |
How to complete a ratio table with a missing number
Suppose one row is 3 : 2 and another is 12 : ?. Choose Find a missing value and enter A = 3, B = 2 and C = 12. The answer is 8, because 2 × 12 ÷ 3 = 8. This homepage mode solves one missing value at a time. To fill several rows together, use the missing-number ratio table calculator.
Ratio to percentage calculator: understand each share
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.
To use the calculator as a ratio-to-percentage converter, choose Simplify a ratio, enter the two parts, and select Calculate. The result shows both the simplest ratio and each part’s percentage of the total. For example, enter 60 and 40 to get 3 : 2, with shares of 60% and 40%. Our ratio-to-percentage calculator also handles three parts.
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.
FIND THE RIGHT METHOD
More ways to use ratios
Use the four free calculator modes for two-number ratios, missing values, proportional scaling and two-way cost splits. For a complete table, three-number ratios or percentage shares, explore the dedicated calculators above.
How to compare ratios
Simplify each pair and compare the results: 18 : 12 and 150 : 100 both reduce to 3 : 2. Alternatively, compare cross-products. The ratios 3 : 2 and 12 : 8 are equal because 3 × 8 = 2 × 12.
Use the ratio simplifier instructions for reduction, or the proportion formula when one value is missing.
Convert a fraction or percentage to a ratio
If one share is 60% of a total, the remaining share is 40%. The part-to-part ratio is 60 : 40 = 3 : 2; the part-to-whole ratio is 60 : 100 = 3 : 5. Likewise, a fraction of 3/5 describes 3 parts out of 5, leaving 2 parts.
Check which percentage or fraction you mean before interpreting a result. The free simplifier shows each part’s percentage of the combined total.
Ratio to decimal and three-number ratio examples
To express 0.75 as a ratio, enter 0.75 : 1 in the simplifier: the result is 3 : 4. To convert a ratio back to a decimal comparison, divide its first term by its second: 3 ÷ 4 = 0.75.
The free tool simplifies two numbers. For a three-part ratio such as 6 : 9 : 15, divide all three terms by their shared divisor, 3, to get 2 : 3 : 5. Use the three-number ratio calculator to simplify all three terms together.
Aspect ratio: width and height
Enter 1920 : 1080 in the simplifier to get the screen aspect ratio 16 : 9. For a width of 1280, choose Find a missing value and enter 16, 9 and 1280. The matching height is 720.
The tool calculates dimensions; it does not resize or crop images. The golden ratio is a different relationship, approximately 1.618 : 1, so a short side of 100 corresponds to a long side of about 161.8. There is no dedicated golden-ratio mode.
Scale materials or split an agreed cost
Ten equal sections instead of four gives a scale factor of 10 ÷ 4 = 2.5. Multiply each original quantity by 2.5, keeping its unit unchanged and allowing separately for waste and packaging.
For money, divide a total using an agreed ratio. A $500 total split 3 : 2 becomes $300 and $200. The free mode accepts two shares; the separate Pro download supports several participants.
Understand mixing-ratio instructions
For a specified 2 : 1 ratio and 9 liters total, the quantities are 6 liters and 3 liters. A label specifying 1 part concentrate to 4 parts water instead describes 5 total parts. Read the label’s definition; ratio shorthand can be ambiguous.
Volume and weight ratios are not interchangeable. Follow the manufacturer’s instructions for dilution, paint and other materials. This general tool does not prescribe mixtures, design concrete mixes or determine structural suitability.
MYRATIOTABLE PRO · FROM ROOF & RATIO
Save your projects.
Put your ratios to work.
Scale materials together, split shared costs, save project copies and export reports with MyRatioTable Pro. A $9.99 one-time download for desktop and laptop browsers.
A LITTLE MORE CLARITY
Ratio calculator 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 units of one material and 2 units 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 this calculator simplify a ratio of three numbers?
The homepage simplifier accepts two numbers. Our three-number ratio calculator accepts three. To simplify three numbers manually, divide all three by their greatest common divisor. For 6 : 9 : 15, divide every term by 3 to get 2 : 3 : 5. Do not leave out the third term.
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, project 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 23, 2026.