Unit converter for kids
Convert length, weight, capacity and time, in metric or customary units, and see every step of the working.
🧒 Kids: type 3, pick feet and inches, and read the steps. Will the answer be bigger or smaller? Guess first!
Measurement unit converter
What the converter shows
- The answer, exact within one system and rounded between systems (marked ≈).
- The steps: the conversion fact, like 1 ft = 12 in, and whether to multiply or divide.
- A table of how one unit compares with every other unit of the same kind.
Use it to check homework, not to replace it. Ask your child to predict whether the number gets bigger or smaller before looking.
Ready-made conversions to open
Each link opens the converter with the problem filled in.
- 3 feet to inches: multiply by 12
- 48 inches to feet: divide by 12
- 2.5 km to meters: a decimal amount
- 3 kg to grams: metric mass
- 2 pounds to ounces: customary weight
- 5 gallons to quarts: customary capacity
- 1.5 liters to milliliters: metric capacity
- 2.5 hours to minutes: time
- 10 inches to centimeters: between systems
The one rule for converting units
Bigger unit to smaller unit: multiply. A smaller unit fits in more times, so the number grows. 4 m = 4 × 100 = 400 cm.
Smaller unit to bigger unit: divide. Fewer of the bigger unit are needed, so the number shrinks. 36 in = 36 ÷ 12 = 3 ft.
A quick check catches most mistakes: if you changed to a smaller unit, your answer should be a bigger number.
Metric units are place value
Metric units go up in steps of 10, 100 and 1,000, so converting is the same as multiplying by 10, 100 and 1,000. The prefixes tell you the size: kilo means 1,000, centi means one hundredth and milli means one thousandth.
| Length | Mass | Capacity |
|---|---|---|
| 1 cm = 10 mm | 1 g = 1,000 mg | 1 L = 1,000 mL |
| 1 m = 100 cm | 1 kg = 1,000 g | |
| 1 km = 1,000 m |
Customary units to know
| Length | Weight | Capacity |
|---|---|---|
| 1 ft = 12 in | 1 lb = 16 oz | 1 cup = 8 fl oz |
| 1 yd = 3 ft = 36 in | 1 ton = 2,000 lb | 1 pt = 2 cups |
| 1 mi = 5,280 ft | 1 qt = 2 pt, 1 gal = 4 qt |
Customary units each have their own number, so they have to be learned. The customary units lesson has a few memory tricks.
Converting units of time
Time uses 60, 24 and 7: 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day and 7 days in a week. A decimal like 2.5 hours means 2 hours and half an hour, which is 150 minutes, not 250.
Common mistakes the steps catch
- Dividing instead of multiplying: 5 ft becomes 0.4 in. Ask whether the answer should be bigger or smaller.
- Using the wrong fact: 3 yd = 30 ft. One yard is 3 feet, not 10.
- Treating time as decimal: 1.5 hours = 150 minutes. It is 90 minutes, because an hour has 60 minutes.
- Mixing units in a sum: 2 m + 50 cm = 52. Change to one unit first: 200 cm + 50 cm = 250 cm.
Unit conversion by grade
| Grade | What children convert | Standard |
|---|---|---|
| Grade 3 | Measure mass in grams and kilograms and liquid volume in liters | 3.MD.A.2 |
| Grade 4 | Bigger units to smaller units, with conversion tables | 4.MD.A.1 |
| Grade 5 | Both directions, including decimals, in multi-step problems | 5.MD.A.1 |
In India, the NCERT books use metric units throughout, so the metric tables matter most for CBSE students.
For teachers
Project the converter and ask the class to predict the answer before you change the units. Share a link with the problem filled in, like ?from=kg&to=g&v=2.5. Nothing is stored and no login is needed.
More measurement help
- Measurement practice: 10 questions on any of 18 skills, with clocks, coins and rulers.
- Interactive clock: move the hands, read the time in words and quiz yourself.
- Unit converter: length, weight, capacity and time, with the steps.
- Time and money: elapsed time · units of time · counting coins · making change
- Measurement quiz for grades 1 to 5, and measurement levels: 8 steps with a test each.
- Measurement games: Clock Race, Time Match and Measurement Bingo.
- Lessons: how to tell time · how to count money · measuring length · weight and mass · capacity · metric units · customary units · word problems
- By grade: 2nd grade · 3rd grade · 4th grade measurement
- Worksheets: telling time · money · metric units · customary units
- Charts: time chart · US coins chart · measurement conversion chart
Back to measurement for kids · 2nd grade math · 3rd grade math · 4th grade math
Last reviewed
Questions parents ask
How do I use the unit converter?
Pick length, weight, capacity or time, type an amount and choose the units. The answer appears with the steps: multiply when going to a smaller unit, divide when going to a bigger one.
Why do you multiply to change feet into inches?
An inch is smaller than a foot, so you need more of them. 1 foot = 12 inches, so 3 feet = 3 × 12 = 36 inches.
Can it convert between metric and customary units?
Yes. Changing between systems gives a rounded answer, because the units don’t fit evenly. For example, 1 inch = 2.54 cm and 1 kg is about 2.2 pounds.
Which conversions do children need to know?
Within one system: 1 m = 100 cm, 1 km = 1,000 m, 1 kg = 1,000 g, 1 L = 1,000 mL, 1 ft = 12 in, 1 yd = 3 ft, 1 lb = 16 oz and 1 gal = 4 qt. Grades 4 and 5 learn these.
Can I link to a conversion?
Yes. Add ?from=, &to= and &v= to the address, like /measurement/unit-converter/?from=kg&to=g&v=2.5. The converter opens with that problem filled in.
Is it OK for my child to use a converter?
Yes, for checking. Ask your child to say whether the answer should be bigger or smaller first, then work it out and compare with the steps.