All skills Math

Learn Index · Measurement Grade 3–5

Measuring liquid volume and capacity

Volume is the space a liquid takes up; capacity is how much a container holds.

Read

Capacity and volume

  • Capacity is how much a container can hold when full.
  • Liquid volume is how much liquid is actually in it.

A 2 L jug has a capacity of 2 L. If it’s half full, the liquid volume is 1 L.

Metric units

Unit Symbol Equals Example
Millilitre mL — a teaspoon is about 5 mL
Litre L 1,000 mL a large milk carton
Kilolitre kL 1,000 L a large water tank

1 mL of water fills a cube 1 cm on each side, so 1 mL = 1 cm³. A litre fills a cube 10 cm on each side.

Measuring tools

Tool Use
Measuring cup cooking; marked in mL and cups
Measuring spoons small amounts (5 mL, 15 mL)
Jug or beaker larger amounts
Graduated cylinder science; accurate readings
Syringe very small amounts, like medicine

How to read a measuring container

  1. Put it on a flat surface.
  2. Bend down so your eyes are level with the liquid.
  3. In a narrow container, water curves down slightly in the middle. This curve is the meniscus. Read the bottom of the curve.
  4. Work out what each mark is worth: if 5 marks span 0 to 50 mL, each mark is 10 mL.

Choosing a unit

Container Unit
A spoon mL
A juice box mL (about 200 mL)
A bathtub L (about 150 L)
A swimming pool kL

Converting

  • L → mL: × 1,000. 1.5 L = 1,500 mL.
  • mL → L: ÷ 1,000. 250 mL = 0.25 L.

Tall isn’t always more

A tall, thin glass can hold less than a short, wide bowl. To compare capacities fairly, pour from one container into the other or measure each.

Worked examples

Example 1: A bottle holds 750 mL. How many litres?

750 ÷ 1,000 = 0.75 L.

Example 2: How many 250 mL cups can you fill from a 2 L jug?

2,000 ÷ 250 = 8 cups.

Example 3: A recipe needs 15 mL of oil. How many 5 mL teaspoons?

15 ÷ 5 = 3 teaspoons.

Common mistakes

  • Reading from above or below instead of at eye level.
  • Reading the top of the meniscus.
  • Confusing mL and L. A glass holds about 250 mL, not 250 L!

Try it yourself

  1. Convert 3 L to mL.
  2. Convert 600 mL to L.
  3. A 1 L carton is poured equally into 4 glasses. How much in each?
  4. Which unit for a raindrop?

Answers: 1) 3,000 mL 2) 0.6 L 3) 250 mL 4) mL

Quick recap

  • Capacity is how much a container holds; liquid volume is how much is in it.
  • 1 litre = 1,000 millilitres.
  • Read at eye level, from the bottom of the meniscus.