What this calculator does
Find out how much of something goes with exactly one of something else. That's a unit rate. Miles per hour, dollars per pound and words per minute are all unit rates.
Enter an amount and how many units it covers, and you'll get the rate for one. You can also enter two prices with their sizes to see which one costs less per unit.
Where it's used
Why this math matters outside the classroom:
- Speed on a trip. A driver who covers 150 miles in 2.5 hours divides to find an average speed of 60 miles per hour.
- Grocery shopping. A shopper finds a 24-ounce box at $4.80 costs $0.20 an ounce, less than a 16-ounce box at about $0.22.
- Hourly pay. A worker paid $340 for 20 hours divides to find a rate of $17 an hour.
- Typing tests. A student who types 450 words in 10 minutes has a rate of 45 words per minute.
- Fertilizer spreading. A gardener who uses 3 pounds on 600 square feet works out 0.005 pounds per square foot.
Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 6.RP.A.3.b, 6.RP.A.2, 7.RP.A.1. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose a rate per one unit, or a comparison of two prices.
- For a rate, enter the amount and how many units it covers. The unit names are optional.
- For a comparison, enter each price and quantity, using the same unit for both.
- Read the rate or the better price, then look through the steps.
What the inputs mean
- Option B quantity
- Compare like with like. If one item is in pounds and one is in ounces, convert first. For groceries with mixed units, the unit price calculator does that for you.
Formula and method
unit rate = amount ÷ number of units saving = (higher cost − lower cost) ÷ higher cost × 100
A rate compares two different things, such as miles and hours. Dividing by the second number scales the rate down until the second number is 1. That makes rates easy to compare.
The saving is a percent of the higher cost per unit. It tells you how much less you pay for each unit by choosing the better option.
Worked example
You drive 150 miles in 2.5 hours. Later, you compare a 24-ounce box for $4.80 with a 16-ounce box for $3.50.
- Divide the miles by the hours: 150 ÷ 2.5 = 60.
- For the boxes, $4.80 ÷ 24 = $0.20 an ounce.
- The other box costs $3.50 ÷ 16 = $0.21875 an ounce.
Result: You drove 60 miles per hour. The 24-ounce box is the better price, saving about 8.57% per ounce.
Understanding the result
A higher rate isn't always better. More miles per gallon is good, but more dollars per ounce isn't. Think about what the number means for you.
The flip side of a rate is also useful. At 60 miles per hour, each mile takes 1/60 of an hour, which is one minute.
Assumptions and limitations
- The rate stays steady across the whole amount. A trip's rate is an average, even if your speed varied.
- A comparison assumes both options use the same unit and that you'll use all of each.
- It doesn't convert between units.
- It compares price only. Quality, or food going to waste, can change which deal is truly better.
Frequently asked questions
What is a unit rate?
It's a rate with 1 in the second place, such as 60 miles per 1 hour. You'd usually say 60 miles per hour.
Which number goes on top?
Put the thing you want to count on top. For dollars per pound, dollars go on top and pounds on the bottom.
Can a unit rate use fractions?
Yes. If you walk 1/2 mile in 1/4 hour, your rate is 0.5 ÷ 0.25 = 2 miles per hour.
How this calculator is checked
Method: Standard ratio arithmetic. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-31. Found a problem? Tell us.
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