4th Grade · 5th Grade · 4.MD.A.1 · 5.MD.A.1

Measurement conversions in 4th and 5th grade

Measurement conversions mean writing the same amount in a different unit, such as 2 feet as 24 inches. In 4th grade, your child learns how big each unit is and changes a larger unit into a smaller one. In 5th grade, your child converts in both directions, uses decimals and solves word problems that take more than one step.

What the standards say

The official Common Core wording, quoted exactly. The plain version follows.

4.MD.A.1 Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two-column table.

5.MD.A.1 Convert among different-sized standard measurement units within a given measurement system (e.g., convert 5 cm to 0.05 m), and use these conversions in solving multi-step, real world problems.

What it means, in plain words

4th grade: how big each unit is 4.MD.A.1

A unit is the amount you measure with, such as a meter or a pound. Your child works with two systems of units. The metric system uses kilometers, meters and centimeters for length, kilograms and grams for weight and liters and milliliters for liquids. Customary units of measurement are the ones used every day in the US, such as inches, feet, pounds and ounces. Time (hours, minutes and seconds) is part of this work too.

Converting units in 4th grade starts with knowing how the units compare. A kilometer is 1,000 meters and a meter is 100 centimeters. A kilogram is 1,000 grams and a liter is 1,000 milliliters. A pound is 16 ounces and a foot is 12 inches. An hour is 60 minutes and a minute is 60 seconds.

Measurement conversions in 4th grade go from a larger unit to a smaller one. Each larger unit holds many smaller ones, so the number gets bigger and your child multiplies. The results go in a two-column table, with the larger unit on the left and the smaller unit on the right.

Your child should be able to:

Say how many meters are in a kilometer, grams in a kilogram and ounces in a pound
Change a larger unit into a smaller one by multiplying
Fill in a two-column table, such as kilometers and meters
Change a mixed measurement, such as hours and minutes, into the smaller unit

Example

A walking trail is 3 kilometers long. How many meters is that? Show it in a two-column table.

1 kilometer is 1,000 meters.
Table: 1 km is 1,000 m, 2 km is 2,000 m and 3 km is 3,000 m.
$3 \times 1{,}000 = 3{,}000$ , so the trail is 3,000 meters long.

Example

A movie lasts 1 hour 45 minutes. How many minutes long is the movie?

1 hour is 60 minutes.
Add the extra minutes: $60 + 45 = 105$ .
The movie is 105 minutes long.

5th grade: converting both ways, with decimals and word problems 5.MD.A.1

In 5th grade, conversions go both ways. Going from a smaller unit to a larger one makes the number smaller, so your child divides. For example, 36 inches is 3 feet, because $36 \div 12 = 3$ . Customary units now also include yards, and cups, pints, quarts and gallons for liquids. A yard is 3 feet. A pint is 2 cups, a quart is 2 pints and a gallon is 4 quarts.

Metric conversions now use decimals. A centimeter is $\frac{1}{100}$ of a meter, so 250 centimeters is 2.5 meters. Every metric step is 10, 100 or 1,000, so converting units of measurement in the metric system means multiplying or dividing by one of those numbers.

Measurement conversions in 5th grade usually come inside word problems with more than one step. Your child first changes every amount to the same unit and then adds, subtracts, multiplies or divides.

Your child should be able to:

Change a smaller unit into a larger one by dividing
Convert metric units with decimals, such as 250 centimeters to 2.5 meters
Change every amount to the same unit before adding or subtracting
Solve word problems with two or more steps that include a conversion

Example

A roll of tape is 5 meters long. Four pieces are cut from it, each 80 centimeters long. How many centimeters of tape are left?

Change meters to centimeters: $5 \times 100 = 500$ centimeters.
The four pieces use $4 \times 80 = 320$ centimeters.
$500 - 320 = 180$
180 centimeters of tape are left, which is 1.8 meters.

Where children usually get stuck

To change 48 inches to feet, your child multiplies $48 \times 12$ and gets 576 feet.
The child learned "use 12 for feet and inches" without asking which unit is bigger. A foot is bigger than an inch, so there must be fewer feet than inches.
What helps. Before any arithmetic, ask: will the answer have more feet or fewer feet than inches? Fewer means divide. $48 \div 12 = 4$ feet.
Your child adds 1 hour 45 minutes and 2 hours 30 minutes and writes 3 hours 75 minutes.
With whole numbers, you regroup at 10. Time regroups at 60, so 75 minutes is more than an hour and has to be traded.
What helps. Ask how many minutes make an hour. Then trade 60 of the 75 minutes for 1 hour, which gives 4 hours 15 minutes.
Your child adds 2 meters and 50 centimeters and writes 52.
The numbers were added without their units. Meters and centimeters can only be added once both amounts are in the same unit.
What helps. Ask your child to say each number with its unit out loud. Then change 2 meters to 200 centimeters, so the total is 250 centimeters.

Try four practice questions

Real 4th grade questions from our question bank, easiest first. Answer them right here, check each one, and see a worked solution for any question.

1Warm-up
The table below shows the number of minutes in different numbers of hours. Find each missing value labeled A and B.
Hours Minutes
1 60
2 A
4 B
Type each missing value below.
Label Minutes
A
B
Show the answer and how to solve it
A = 120 and B = 240. Each missing minute value is found by multiplying the hour value in that row by 60, the number of minutes in 1 hour.
1. 1Look at the first row of the table. It shows that 1 hour equals 60 minutes. This is the conversion factor: there are 60 minutes in every hour.
2. 2For row A, the table shows 2 hours. Multiply 2 by 60 to find the number of minutes.
3. 3For row B, the table shows 4 hours. Multiply 4 by 60 to find the number of minutes.
4. 4The missing values are A = 120 and B = 240 minutes.
Common mistake. A common mistake is using 10 as a default conversion factor instead of 60, or adding 60 to each row value instead of multiplying the row value by 60.
The idea underneath. Every row in a conversion table follows the same rule: multiply the larger-unit number by the smaller-unit count shown in the 1-unit row. The 1-unit row gives you the conversion factor for the whole table.
2On level
An art club schedule is shown in the table below. The club does Paint Station 2 times. Find the total time in minutes.
Activity Time
Sketch time 20 minutes
Paint Station 25 minutes
Clean-up 1 hour
Enter the total number of minutes.
minutes
Show the answer and how to solve it
Answer. 130
The answer is 130 minutes because the two Paint Station sessions take 50 minutes, and $20 + 50 + 60 = 130$ .
1. 1Use the 25-minute Paint Station row twice because the club does that activity 2 times.
2. 2Find the total time for the two Paint Station sessions.
3. 3Convert the 1-hour clean-up time to minutes.
4. 4Now all the times are in minutes, so add them.
Common mistake. A common mistake is counting the 25-minute Paint Station only once or treating 1 hour as 100 minutes. Use both sessions and convert 1 hour to 60 minutes before adding.
The idea underneath. Convert all the times to the same unit before you combine them.
3On level
Find the missing number to complete the equation.
$\displaystyle 6 \text{ gal} = \underline{\phantom{000}} \text{ qt}$
qt
Show the answer and how to solve it
Answer. 24
The missing number is $24$ . Since $1$ gallon equals $4$ quarts, $6$ gallons is $6 \times 4 = 24$ quarts.
1. 1Look at the equation. It shows $6$ gallons on the left and asks for the same amount written in quarts.
2. 2Remember the size of each unit: $1$ gallon equals $4$ quarts. Because quarts are smaller than gallons, $6$ gallons will be a larger number of quarts.
3. 3There are $4$ quarts in each gallon, and there are $6$ gallons, so multiply $6$ by $4$ .
4. 4So $6$ gallons equals $24$ quarts.
Common mistake. A common mistake is multiplying by the wrong conversion factor. Some students use $2$ (which is the quarts-to-pints relationship) instead of $4$ when changing gallons to quarts, getting $6 \times 2 = 12$ instead of $24$ .
The idea underneath. When changing a larger unit to a smaller unit, multiply by the number of smaller units that fit inside one larger unit. Smaller units always need a larger count to measure the same amount.

Hours	Minutes
1	60
2	A
4	B

Label	Minutes
A
B

Activity	Time
Sketch time	20 minutes
Paint Station	25 minutes
Clean-up	1 hour

4Stretch

One batch of punch uses the amounts in the table. How many pints of liquid are used altogether?

Ingredient	Amount
Lemonade	1 quart
Water	3 pints
Fruit juice	2 cups

Fill in the blanks to complete the organizer.

Convert quart	$\displaystyle 1 \text{ quart} =$ $\displaystyle \text{ cups}$
Convert pints	$\displaystyle 3 \text{ pints} =$ $\displaystyle \text{ cups}$
Find total in cups	$\displaystyle \text{Total} =$ $\displaystyle \text{ cups}$
Convert to pints	$\displaystyle \text{Total} =$ $\displaystyle \text{ pints}$

Show the answer and how to solve it

The answer is 6 pints because 1 quart is 4 cups, 3 pints is 6 cups, $4 + 6 + 2 = 12$ cups, and $12 \div 2 = 6$ pints.

1The table shows 1 quart of lemonade, 3 pints of water, and 2 cups of fruit juice. Convert the quart and the pints to cups first.
2Each quart is 4 cups, so 1 quart is 4 cups.
3Each pint is 2 cups, so 3 pints is 6 cups.
4Now all amounts are in cups. Add 4, 6, and 2.
5Each pint is 2 cups, so divide 12 by 2 to convert back to pints.

Common mistake. A common mistake is forgetting to convert the final total back to pints. In this problem, 12 cups must be divided by 2 to get 6 pints.

The idea underneath. Convert every amount to the same customary unit before you add them.