Volume (cubic centimetres) and capacity (millilitres and litres) are linked. A 1 cm cube holds exactly 1 mL of water, so the number of cm³ equals the number of mL. A litre is 1000 mL, so 1000 cm³ = 1 L. To change cm³ into litres, divide by 1000. To find how many litres a tank holds, first find its volume with length × width × height, then divide by 1000.
Explore this idea with maths tools
Maths you can move
Build 8 + 5
Tap two gold counters to fill the ten-frame.
8 in the frame + 5 waiting. The total stays the same.
Words to know
- capacity
- how much a container can hold
- millilitre (mL)
- a small unit of capacity: 1 mL fills a 1 cm cube
- litre (L)
- 1000 millilitres, which fills 1000 cm³
Worked examples
250 cm³ = ? mL
- 1.1 cm³ holds exactly 1 mL.
- 2.250 cm³ = 250 mL.
= 250
3000 cm³ = ? L
- 1.1000 cm³ = 1 L, so divide by 1000.
- 2.3000 ÷ 1000 = 3 L.
= 3
A tank is 20 cm × 10 cm × 15 cm. How many litres does it hold?
- 1.Volume = 20 × 10 × 15 = 3000 cm³.
- 2.3000 ÷ 1000 = 3 L.
= 3
For parents
Method: 1 cm³ = 1 mL, 1000 cm³ = 1 L
What to say: Is the new unit bigger or smaller? Which link do you need: 1 or 1000?
Common mistakes:
- Multiplies by 1000 to change cm³ into mL (or back), not knowing that 1 cm³ = 1 mL.
- Divides by 1000 to change cm³ into mL (or back), treating mL like litres.
- Converts with the wrong power of ten (10 or 100 instead of 1, or 100 instead of 1000).
- Multiplies when it should divide (or the reverse), so the number goes the wrong way.
- Over-uses the one-to-one link and treats a litre as if it were one cubic centimetre.
- Finds the volume in cubic centimetres but does not change it into litres.
- Adds the box's length, width and height instead of multiplying to find its volume.