Capacity in litres and millilitres

How much water does your bottle hold? How much milk in a tea-cup? Capacity is the amount of liquid a container can hold. We measure capacity in litres (l) and millilitres (ml).

What is this?

Like kg and g, the units of capacity are related by 1,000:

$1 \text{ litre} = 1{,}000 \text{ millilitres}$

So:

• 2 l = 2,000 ml.
• 500 ml = $\frac{1}{2}$ l = 0.5 l.
• 1 l 250 ml = 1,250 ml.

We use litres for water bottles, milk packets, petrol, oil cans. We use millilitres for medicine, perfume, juice servings, cough syrup.

A common Indian water bottle holds 1 litre. A small medicine bottle holds about 100 ml. A milk packet often holds 500 ml. A petrol tank in a scooter is about 5 litres.

Adding and subtracting capacities follows the same pattern as weights , line up litres with litres and ml with ml. Carry or borrow 1,000 ml when crossing.

For example, 1 l 700 ml + 2 l 500 ml:

• ml: 700 + 500 = 1,200 ml = 1 l 200 ml.
• l: 1 + 2 + 1 = 4 l, with 200 ml left.
• Total = 4 l 200 ml.

Worked examples

Example 1. Convert 3 l 450 ml to ml.

• 3 l = 3,000 ml.
• 3,000 + 450 = 3,450 ml.

Example 2. A juice carton holds 250 ml. How many such cartons make 2 litres?

• 2 l = 2,000 ml.
• 2,000 ÷ 250 = 8 cartons.

Example 3. A bucket has 5 l of water. 1 l 800 ml is poured out. How much is left?

• 5 l = 5,000 ml. 1 l 800 ml = 1,800 ml.
• 5,000 − 1,800 = 3,200 ml = 3 l 200 ml.

Try it

1. Convert 6 l 250 ml to ml.
2. Convert 4,800 ml to l and ml.
3. Add: 2 l 600 ml + 3 l 750 ml.
4. Subtract: 6 l − 2 l 250 ml.
5. A medicine bottle holds 150 ml. How many doses of 10 ml each?

Hands-on

Measuring cup. Take a 1 litre water bottle and a smaller measuring cup. Pour water carefully , count how many small cups fill the litre bottle. If your cup is 250 ml, you should need 4.

Kitchen check. Read labels on bottles in your kitchen , oil, milk, juice, water. Note each capacity. Add the total volume of liquids you have. How many litres in all?