Year 6 Maths 3D Objects, Volume & Capacity

Convert units of capacity

Q: How do I change mL to L?

Divide by 1000: 2600 mL = 2.6 L.

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Theory

Capacity is how much a container holds. The units are millilitres (mL), litres (L) and kilolitres (kL), with \(1\) L \(= 1000\) mL and \(1\) kL \(= 1000\) L. This Year 6 maths page shows how to convert between them, read a measuring jug, compare capacities, and solve problems with bottles, cups and tanks.

Millilitres measure small amounts (a spoon, a cup). Litres measure bottles, buckets and baths. Kilolitres measure tanks and pools.

\(1\) L \(= 1000\) mL and \(1\) kL \(= 1000\) L. Each step is \(\times 1000\) going to the smaller unit and \(\div 1000\) going to the larger unit.

Decimal litres: \(3.75\) L \(= 3750\) mL; \(450\) mL \(= 0.45\) L. Half a litre is \(500\) mL and a quarter of a litre is \(250\) mL.

To read a measuring jug, find the value of each small mark, then count up from the last labelled mark.

The water is at \(700\) mL. Another \(300\) mL would make \(1\) L.

Each step down is \(\times 1000\); each step up is \(\div 1000\).

Capacity units:

\[ 1\text{ L} = 1000\text{ mL} \]

1 L = 1000 mL

\[ 1\text{ kL} = 1000\text{ L} \]

1 kL = 1000 L

\[ 0.5\text{ L} = 500\text{ mL}, \quad 0.25\text{ L} = 250\text{ mL} \]

0.5 L = 500 mL, 0.25 L = 250 mL

          Same unit before comparing. \(1.3\) L and \(1250\) mL: change to \(1300\) mL and \(1250\) mL.
        

Check the size. A smaller unit needs a bigger number.

Converting capacity

To a smaller unit (kL to L, L to mL): multiply by \(1000\).
To a larger unit (mL to L, L to kL): divide by \(1000\).

Sharing into containers

Change both amounts to the same unit.
Divide the total by the size of one container.

Example 1 — L to mL

Convert \(7\) L and \(3.75\) L to millilitres.

Solution

\(7 \times 1000\)	\(=\)	\(7000\)
\(3.75 \times 1000\)	\(=\)	\(3750\)

7000 mL, 3750 mL

\(7000\) mL and \(3750\) mL.

Example 2 — mL to L

Convert to litres.
(i) \(9000\) mL
(ii) \(2600\) mL
(iii) \(450\) mL

Solution

\(9000 \div 1000\)	\(=\)	\(9\)
\(2600 \div 1000\)	\(=\)	\(2.6\)
\(450 \div 1000\)	\(=\)	\(0.45\)

9 L, 2.6 L, 0.45 L

(i) \(9\) L
(ii) \(2.6\) L
(iii) \(0.45\) L

Example 3 — kL to L

A tank holds \(6.2\) kL. How many litres is that?

Solution

\(6.2 \times 1000\)

\(=\)

\(6200\)

6.2 \times 1000 = 6200

\(6200\) L.

Example 4 — Read the jug

Use the first diagram. How much water is in the jug, and how much more is needed to make \(1\) L?

Solution

\(1000 - 700\)

\(=\)

\(300\)

1000 - 700 = 300

\(700\) mL; \(300\) mL more.

Example 5 — Compare and order

(i) Which holds more, \(1.3\) L or \(1250\) mL?
(ii) Order \(2.1\) L, \(1900\) mL, \(2050\) mL from smallest to largest.

Solution

(i) \(1.3\) L (\(1300\) mL)
(ii) \(1900\) mL, \(2050\) mL, \(2.1\) L

Example 6 — A recipe

A smoothie recipe uses \(375\) mL of milk. Ana makes it \(4\) times. How much milk is that in litres?

Solution

\(375 \times 4\)

\(=\)

\(1500\)

375 \times 4 = 1500

\(1500\) mL \(= 1.5\) L.

Example 7 — Buckets and cups

(i) How many \(25\) L buckets can be filled from \(2\) kL?
(ii) How many \(200\) mL cups can be filled from \(3\) L?

Solution

\(2000 \div 25\)	\(=\)	\(80\)
\(3000 \div 200\)	\(=\)	\(15\)

80 buckets, 15 cups

(i) \(80\) buckets (\(2\) kL \(= 2000\) L)
(ii) \(15\) cups (\(3\) L \(= 3000\) mL)

Example 8 — Find the mistake

Leo changed \(4500\) mL to litres by dividing by \(100\) and wrote \(45\) L. What is right?

Solution

\(4500 \div 1000\)

\(=\)

\(4.5\)

4500 \div 1000 = 4.5

There are \(1000\) mL in a litre, so \(4500\) mL \(= 4.5\) L.

Common pitfalls

Dividing by 100. Litres and millilitres differ by \(1000\).

Comparing different units. \(1250\) mL is less than \(1.3\) L.

Misreading a jug. Work out what each small mark is worth first.

Mixing units when sharing. Change the total and the container size to the same unit before dividing.

Frequently asked questions

How many millilitres are in a litre?

\(1000\).

How many litres are in a kilolitre?

\(1000\).

How do I change mL to L?

Divide by \(1000\): \(2600\) mL \(= 2.6\) L.

What unit should I use for a swimming pool?

Kilolitres.

How many 200 mL cups can I fill from 3 L?

\(3000 \div 200 = 15\).

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Convert units of capacity

📖 Theory

Converting capacity

Sharing into containers

Common pitfalls

Frequently asked questions

Theory