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Capacity: Litres & Millilitres

Maths · Y3 Measurement
Year 3
Lesson Guide
Explanation
Capacity is how much liquid fits inside a container. Small amounts use millilitres (mL) — a teaspoon holds about 5 mL, a juice box 250 mL. Big amounts use litres (L) — milk comes in 1 L and 2 L bottles, a bucket holds about 10 L. And the magic number is an old friend: 1000 mL = 1 L, just like grams and kilograms.
Your Turn
mL or L? A raindrop, a swimming pool, a can of soft drink, a fish tank. Check: mL, L (thousands!), mL (375 mL), L.
Watch Out
Capacity is about what fits INSIDE — a huge empty box has lots of capacity even when nothing is in it.
Explanation
A measuring jug has lines up its side, like a ruler for liquids. Pour in the liquid, put the jug on a FLAT surface, bend down so your eyes are level with the liquid, and read the line the surface touches. This jug shows 500 mL — half a litre. The gaps between lines matter too: here each line is 250 mL.
Your Turn
If a jug has lines at 250, 500, 750 and 1000 mL, and the liquid is one line above 500 — how much? Check: 750 mL.
Watch Out
Reading from above or below the liquid line gives the wrong number — eyes LEVEL with the liquid!
Explanation
Converting capacity is the same ×1000 game as mass. Litres to millilitres, multiply: 3 L = 3000 mL. Millilitres to litres, bundle the thousands: 1250 mL = 1 L 250 mL. The shop favourites are worth knowing by heart: half a litre = 500 mL, a quarter = 250 mL — that's your juice box!
Your Turn
Convert: 2 L to mL, and 1750 mL to L-and-mL. Check: 2000 mL; and 1 L 750 mL.
Watch Out
mL and L — one thousand apart, just like g and kg. But metres and cm are only 100 apart. Keep the families straight!
Explanation
Capacity problems follow the rules you already know. Comparing? Match units first: 2 L = 2000 mL beats 1500 mL. Combining? Add: two juice boxes and a bottle — 250 + 250 + 500 = 1000 mL, exactly one litre. Pouring out? Subtract: a 1 L jug minus 300 mL leaves 700 mL. Units first, then the maths is easy.
Your Turn
A recipe needs 1 L of milk. You have a 600 mL carton and a 500 mL carton. Enough? Check: 1100 mL > 1000 mL — yes, with 100 mL spare!
Watch Out
1 L − 300 mL: convert BEFORE subtracting. 1 − 300 makes no sense; 1000 − 300 does.
Explanation
The kitchen is capacity headquarters. A glass holds about 250 mL, so a 1 L bottle fills exactly 4 glasses (4 × 250 = 1000). A soup pot holds about 3 L. And doctors say to drink about 1 to 1.5 L of water a day — that's four to six glasses. Estimate, measure, and check just like a chef. Quiz and exercises now!
Your Turn
How many 250 mL glasses can you pour from a 2 L bottle? Check: 2000 ÷ 250 = 8 glasses.
Watch Out
Containers are rarely filled to the brim — capacity is what a container CAN hold; the amount inside may be less.
Step 1: Introduction
Step 1 of 5
Capacity = how much fits inside 🥄 millilitres (mL) — small drinks a teaspoon ≈ 5 mL a juice box ≈ 250 mL 🪣 litres (L) — big amounts a milk bottle = 1 L or 2 L a bucket ≈ 10 L 1000 mL = 1 L Same ×1000 magic number as grams and kilograms! A big water bottle is 600 mL; a bathtub holds about 150 L.
Read at the liquid line 1 L 750 mL 500 mL 250 mL read here! The liquid sits at the 500 mL line — half a litre.
L ↔ mL — the ×1000 game again 3 L = 3 × 1000 = 3000 mL 1250 mL = 1 L and 250 mL half a litre = 500 mL · quarter = 250 mL Drink labels use these: 375 mL can, 600 mL bottle, 2 L juice.
Which holds more? A 2 L bottle vs a 1500 mL jug? 2 L = 2000 mL > 1500 mL → the bottle holds more. Two 250 mL juice boxes and a 500 mL bottle — total? 250 + 250 + 500 = 1000 mL = exactly 1 L! A 1 L jug pours 300 mL. How much is left? 1000 − 300 = 700 mL left. Rule one, as always: make the units match before comparing!
Chef maths 👨‍🍳 🥛 glass of milk ≈ 250 mL 🍲 soup pot ≈ 3 L 🫗 4 glasses from a 1 L bottle (4 × 250) 💧 drink each day ≈ 1 to 1.5 L A 1 L bottle fills exactly 4 glasses of 250 mL. Quiz time!
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