Volume & Capacity — Grade 4 Mathematics
In Grade 4, we work with decimal capacities (e.g., 1.75 L), convert fluently between ml and litres, and solve multi-step real-world problems involving capacity and volume.
Key Conversions
1 litre (L) = 1 000 millilitres (ml)
• ml → L: divide by 1 000 • L → ml: multiply by 1 000
Decimal notation: 1 L 750 ml = 1.75 L • 2 500 ml = 2.5 L • 350 ml = 0.35 L
• ml → L: divide by 1 000 • L → ml: multiply by 1 000
Decimal notation: 1 L 750 ml = 1.75 L • 2 500 ml = 2.5 L • 350 ml = 0.35 L
1 L
750 ml
500 ml
250 ml
1 L = 1 000 ml
1 L
750 ml
500 ml
250 ml
750 ml = 0.75 L
1 L
750 ml
500 ml
250 ml
350 ml = 0.35 L
Worked Examples
Example 1 — Convert to Litres
Write 2 450 ml as litres.
- 2 450 ÷ 1 000 = 2.45 L
Example 2 — Add and Convert
A jug contains 1.3 L. Another 850 ml is added. How much is there in total? Give your answer in litres.
- Convert 850 ml → 0.85 L
- 1.3 + 0.85 = 2.15 L
Example 3 — Multi-Step Sharing 🧃
5 bottles each hold 750 ml. How many litres is this in total?
- 5 × 750 = 3 750 ml
- 3 750 ÷ 1 000 = 3.75 L
Practice Questions
1. Convert 4 600 ml to litres.
✅ 4 600 ÷ 1 000 = 4.6 L
2. Convert 3.25 L to ml.
✅ 3.25 × 1 000 = 3 250 ml
3. A tank holds 8 L. A tap releases 1.75 L per minute for 3 minutes. How much remains?
✅ 1.75 × 3 = 5.25 L released; 8 − 5.25 = 2.75 L
4. Write 2 L 350 ml as a decimal in litres.
✅ 350 ml = 0.35 L; total = 2.35 L
5. A recipe needs 500 ml of water. How many times can you use a 125 ml cup to measure this?
✅ 500 ÷ 125 = 4 times
Key Points to Remember
- 1 L = 1 000 ml — the only conversion you need for capacity.
- ml → L: divide by 1 000; L → ml: multiply by 1 000.
- Decimal capacity: 1 L 350 ml = 1.35 L.
- Always convert to the same unit before adding or subtracting.
- Volume (of a solid) and capacity (of a container) both use the same units: ml and L.