Converting cm to m and m to cm
Centimetres and metres measure the same thing — length. Sometimes you need to convert between them. Converting means changing a measurement from one unit to another without changing the actual length.
In Class 3, you learn the simple rule: 1 m = 100 cm, and use multiplication and division to convert.
What is Converting cm to m and m to cm - Class 3 Maths (Measurement)?
To convert m to cm: Multiply by 100
To convert cm to m: Divide by 100
Mixed units: 2 m 35 cm means 2 metres and 35 extra centimetres. In cm only: 200 + 35 = 235 cm.
Converting cm to m and m to cm Formula
m to cm → × 100 | cm to m → ÷ 100
| Metres | Centimetres |
|---|---|
| 1 m | 100 cm |
| 2 m | 200 cm |
| 3 m | 300 cm |
| 5 m | 500 cm |
| 10 m | 1000 cm |
Solved Examples
Example 1: Convert m to cm
Question: Convert 4 m to cm.
Think:
- 1 m = 100 cm
- 4 m = 4 × 100 = 400 cm
Answer: 4 m = 400 cm.
Example 2: Convert cm to m
Question: Convert 300 cm to m.
Think:
- 300 ÷ 100 = 3
Answer: 300 cm = 3 m.
Example 3: Mixed to cm
Question: Convert 3 m 45 cm to cm only.
Think:
- 3 m = 300 cm
- 300 + 45 = 345 cm
Answer: 3 m 45 cm = 345 cm.
Example 4: cm to Mixed
Question: Express 278 cm in m and cm.
Think:
- 278 ÷ 100 = 2 remainder 78
- 2 m and 78 cm
Answer: 278 cm = 2 m 78 cm.
Example 5: Word Problem — Height
Question: Aman is 1 m 32 cm tall. Priya is 128 cm tall. Who is taller?
Think:
- Aman: 1 m 32 cm = 132 cm
- Priya: 128 cm
- 132 > 128
Answer: Aman is taller by 4 cm.
Example 6: Addition with Conversion
Question: A rope is 2 m 60 cm. Another rope is 1 m 50 cm. What is the total length?
Think:
- 2 m 60 cm + 1 m 50 cm
- m: 2 + 1 = 3 m
- cm: 60 + 50 = 110 cm = 1 m 10 cm
- Total: 3 + 1 = 4 m 10 cm
Answer: Total = 4 m 10 cm.
Example 7: Subtraction with Conversion
Question: A cloth is 5 m long. Ria cuts off 2 m 30 cm. How much is left?
Think:
- 5 m = 500 cm
- 2 m 30 cm = 230 cm
- 500 − 230 = 270 cm = 2 m 70 cm
Answer: 2 m 70 cm is left.
Example 8: Comparing Lengths
Question: Which is longer: 450 cm or 4 m?
Think:
- 4 m = 400 cm
- 450 > 400
Answer: 450 cm is longer (by 50 cm).
Example 9: Word Problem — Fabric
Question: Neha buys 6 m of fabric. She uses 375 cm for a dress. How much fabric is left?
Think:
- 6 m = 600 cm
- 600 − 375 = 225 cm = 2 m 25 cm
Answer: 2 m 25 cm of fabric is left.
Key Points to Remember
- 1 m = 100 cm is the key conversion fact.
- To convert m to cm, multiply by 100.
- To convert cm to m, divide by 100.
- For mixed units (like 3 m 45 cm), convert everything to one unit before adding or subtracting.
- Always convert to the same unit before comparing lengths.
- When cm exceeds 100 after addition, regroup: 160 cm = 1 m 60 cm.
Practice Problems
- Convert 7 m to cm.
- Convert 500 cm to m.
- Express 4 m 15 cm in cm only.
- Express 362 cm in m and cm.
- Kavi's rope is 2 m 40 cm. Dev's rope is 190 cm. Whose rope is longer?
- Add: 3 m 75 cm + 2 m 50 cm.
- Subtract: 4 m − 1 m 65 cm.
Frequently Asked Questions
Q1. How many cm are in 1 m?
There are 100 cm in 1 m.
Q2. How do I convert metres to centimetres?
Multiply the number of metres by 100. For example, 5 m = 5 × 100 = 500 cm.
Q3. How do I convert centimetres to metres?
Divide by 100. For example, 350 cm = 350 ÷ 100 = 3 m 50 cm.
Q4. What does '2 m 45 cm' mean?
It means 2 full metres plus 45 extra centimetres. In cm only, it is 200 + 45 = 245 cm.
Q5. How do I add lengths in m and cm?
Add the metres and centimetres separately. If the cm total is 100 or more, convert: 160 cm = 1 m 60 cm, and add the extra metre.
Q6. How do I subtract lengths in m and cm?
Convert both to cm, subtract, then convert back to m and cm. Or borrow: 5 m 20 cm − 2 m 70 cm → borrow 1 m → 4 m 120 cm − 2 m 70 cm = 2 m 50 cm.
Q7. Why do we need to convert?
You must have both measurements in the same unit to compare, add, or subtract them. You cannot directly add 2 m and 50 cm without converting.
Q8. Is this topic in NCERT Class 3?
Yes. NCERT Class 3 Maths covers conversion between cm and m, along with addition, subtraction, and comparison of lengths.
