Master metric conversions, imperial units, time, timetables and perimeter!
| Measurement | Conversion | Example |
|---|---|---|
| Length: km ↔ m | × 1000 / ÷ 1000 | 3.5 km = 3500 m |
| Length: m ↔ cm | × 100 / ÷ 100 | 2.4 m = 240 cm |
| Length: cm ↔ mm | × 10 / ÷ 10 | 7.5 cm = 75 mm |
| Mass: kg ↔ g | × 1000 / ÷ 1000 | 0.75 kg = 750 g |
| Mass: g ↔ mg | × 1000 / ÷ 1000 | 250 mg = 0.25 g |
| Capacity: l ↔ ml | × 1000 / ÷ 1000 | 1.5 l = 1500 ml |
Memory tip: kilo = 1000, centi = 1/100, milli = 1/1000. To convert to SMALLER unit, × (multiply). To convert to LARGER unit, ÷ (divide).
| Imperial | Approx. Metric | Memory Aid |
|---|---|---|
| 1 mile | ≈ 1.6 km | 5 miles ≈ 8 km |
| 1 pound (lb) | ≈ 454 g (≈ 0.45 kg) | 2.2 lbs ≈ 1 kg |
| 1 pint | ≈ 568 ml | 1.75 pints ≈ 1 litre |
| 1 inch | ≈ 2.54 cm | 1 foot = 12 inches ≈ 30 cm |
| 1 foot | ≈ 30.5 cm | 5 feet ≈ 1.5 m |
| 12-hour | 24-hour |
|---|---|
| 12:00 midnight | 00:00 |
| 1:00 am | 01:00 |
| 12:00 noon | 12:00 |
| 1:00 pm | 13:00 |
| 6:30 pm | 18:30 |
| 11:59 pm | 23:59 |
Rule: For pm times (except 12 pm), add 12 to get 24-hour. For 24-hour > 12:00, subtract 12 to get pm.
To find how long from one time to another, count in stages:
Example: How long from 9:45 am to 2:15 pm?
9:45 → 10:00 = 15 min
10:00 → 2:00 pm = 4 hours
2:00 → 2:15 = 15 min
Total = 4 hours 30 minutes
For L-shapes and recessed shapes, find the missing side lengths using the known sides, then add all sides.
Key: Opposite sides of a compound shape add up to the same total. Use this to find missing lengths before adding the perimeter.
Example: An L-shape has outer dimensions 10 cm × 8 cm with a 4×3 notch cut from the corner. Perimeter = 10+8+4+3+(10-4)+(8-3) = 10+8+4+3+6+5 = 36 cm
Q: Convert 3.75 km to metres.
km → m: multiply by 1000 (going to smaller unit)
3.75 × 1000 = 3750 m
Q: A road sign says 40 miles. Approximately how many km is this?
5 miles ≈ 8 km, so 1 mile ≈ 1.6 km
40 × 1.6 = 64 km
Or: 40 ÷ 5 × 8 = 8 × 8 = 64 km
Q: A film starts at 19:45. What time is this in 12-hour format?
19:45 is after 12:00, so it's pm. 19 − 12 = 7
Answer: 7:45 pm
Q: A train leaves at 08:47 and arrives at 11:23. How long is the journey?
08:47 → 09:00 = 13 minutes
09:00 → 11:00 = 2 hours
11:00 → 11:23 = 23 minutes
Total = 2 hours 36 minutes
Q: An L-shape has sides: 8cm, 5cm, 3cm, 2cm, and two missing sides. Find the perimeter.
Missing horizontal side = 8 − 3 = 5 cm
Missing vertical side = 5 − 2 = 3 cm
Perimeter = 8 + 5 + 3 + 2 + 5 + 3 = 26 cm
Enter a value and choose a conversion to see the result!
Enter a 24-hour time to see 12-hour, or type 12-hour to convert:
Drag the correct equivalent measurement to each box.
1. 3 km =
2. 2.5 m =
3. 4.5 cm =
4. 800 m =
5. 65 mm =
Drag the correct equivalent.
1. 1.5 kg =
2. 350 g =
3. 2 litres =
4. 750 ml =
5. 4.5 l =
Drag the approximate metric equivalent. Use: 5 miles ≈ 8 km, 1 kg ≈ 2.2 lbs, 1 pint ≈ 568 ml.
1. 10 miles ≈
2. 5 lbs ≈
3. 2 pints ≈
4. 25 miles ≈
5. 1 lb ≈
Drag the correct 24-hour time for each 12-hour time.
1. 7:30 am =
2. 1:45 pm =
3. 8:15 pm =
4. 12 midnight =
5. 12:00 noon =
Drag the correct duration for each journey.
1. 09:15 to 11:45
2. 14:30 to 16:15
3. 07:45 to 11:00
4. 10:00 to 10:45
5. 08:50 to 13:00
Find the perimeter of each compound shape by dragging the correct answer.
1. L-shape: outer 10×8, notch 4×3 cut from corner. Perimeter = ?
2. Rectangle 12×8 cm. Perimeter = ?
3. L-shape: outer 9×6, notch 3×2. Perimeter = ?
4. Rectangle 7×4 cm. Perimeter = ?
5. L-shape: outer 12×10, notch 5×2. Perimeter = ?
1. Convert 4.5 km to metres.
2. Convert 380 cm to metres.
3. Convert 2750 g to kilograms.
4. Convert 1.25 litres to millilitres.
5. A road sign says 15 miles. Approximately how many km is this?
6. Convert 16:45 to 12-hour time.
7. Convert 8:30 pm to 24-hour time.
8. How long from 10:15 am to 1:45 pm?
9. A bus leaves at 09:40 and the journey takes 1 hour 25 minutes. What time does it arrive?
10. An L-shape has outer dimensions 8 cm × 6 cm with a 2×3 notch removed. What is the perimeter?
11. Convert 85 mm to centimetres.
12. What is 1 am in 24-hour time?
13. How long from 23:15 to 01:45 (next day)?
14. Convert 3 lbs approximately to kg.
15. A train timetable shows: depart 13:52, arrive 15:27. How long is the journey?
16. Convert 6.2 cm to millimetres.
17. What is 12 midnight in 24-hour time?
18. A rectangle is 15 cm × 9 cm. What is its perimeter?
19. Convert 5 pints to an approximate number of millilitres.
20. How long from 07:48 to 10:12?
1. Maria runs 5 km every morning. How many miles is this approximately?
2. A film starts at 14:35 and lasts 2 hours 48 minutes. What time does it end (24-hour format)?
3. An L-shaped garden has outer measurements 15 m × 12 m. A rectangular shed 4 m × 3 m sits in one corner (inside the garden). What is the perimeter of the garden?
4. A recipe needs 1.2 kg of flour. The bag of flour weighs 2 lbs 3 oz. Is there enough? (1 lb ≈ 454 g, 1 oz ≈ 28 g)
5. A train timetable: Train A departs 08:14, arrives 10:09. Train B departs 09:47, arrives 11:18. Which train takes less time? By how much?
6. Convert 3 feet 6 inches to centimetres. (1 foot ≈ 30.5 cm, 1 inch ≈ 2.54 cm)
7. A runner completes a 10 km race in 52 minutes. At this pace, how long would it take to run a 5 km race?
8. A compound shape (cross shape) is a 6 cm × 6 cm square with 2 cm × 2 cm squares added to each of the 4 sides. What is the total perimeter?
9. How many 250 ml cups can be filled from a 4.5 litre bottle?
10. A holiday flight departs London at 06:45 and arrives in Dubai 7 hours 20 minutes later. Dubai is 4 hours ahead of London. What is the local Dubai arrival time?