How it works
This is a metric conversion practice game: an amount appears and you type what it is in another unit. Choose what to practise (length, mass, capacity, time or all of them) and a level:
- Easy – from a bigger unit to a smaller one: 7 m = ? cm, 3 l = ? ml.
- Medium – both directions: 4000 g = ? kg, 120 min = ? h.
- Hard – mixed units: 2 m 35 cm = ? cm, 3250 g = ? kg ? g.
After every answer the game shows the working. Hints draws the conversion ladder under each question – switch it off once you know it. Every 12 questions you get a grade, and you can replay the ones you got wrong.
Metric conversion chart
| Quantity | Conversions |
|---|---|
| Length | 1 km = 1000 m · 1 m = 100 cm · 1 cm = 10 mm |
| Mass | 1 t = 1000 kg · 1 kg = 1000 g |
| Capacity | 1 l = 100 cl = 1000 ml · 1 cl = 10 ml |
| Time | 1 day = 24 h · 1 h = 60 min · 1 min = 60 s |
Useful facts: 1 m = 1000 mm, 1 km = 100,000 cm, 1 hour = 3600 seconds, 1 day = 1440 minutes.
The rule in one sentence
Bigger to smaller: multiply. Smaller to bigger: divide. When metres become centimetres the number gets bigger (7 m = 700 cm), because a centimetre is smaller, so you need more of them. When grams become kilograms the number gets smaller (3000 g = 3 kg).
- Find the conversion factor. m → cm: 100, kg → g: 1000, l → ml: 1000, h → min: 60.
- Decide the direction. Multiply towards the smaller unit, divide towards the bigger one.
- Split mixed amounts. 2 m 35 cm = 200 cm + 35 cm = 235 cm. Backwards: 3250 g holds 1000 three times with 250 left over → 3 kg 250 g.
- Estimate. A door is about 2 m tall, a bag of sugar 1 kg, a glass of water 250 ml – so you notice straight away if an answer is way off.
Frequently asked questions
How do you convert metric units?
From a bigger unit to a smaller one you multiply (7 m = 7 × 100 = 700 cm); from a smaller unit to a bigger one you divide (3000 g = 3000 ÷ 1000 = 3 kg). All you need to know is how many of the smaller unit fit in the bigger one.
How many centimetres are in a metre?
1 m = 100 cm = 1000 mm, and 1 cm = 10 mm. 1 km = 1000 m.
How many grams are in a kilogram?
1 kg = 1000 g. 1 tonne = 1000 kg.
How many millilitres are in a litre?
1 l = 1000 ml = 100 cl, and 1 cl = 10 ml.
How many minutes are in an hour, and hours in a day?
1 day = 24 hours, 1 hour = 60 minutes, 1 minute = 60 seconds. Time does not go in tens, so it is worth practising on its own.
What does the Hard level practise?
Mixed units: 2 m 35 cm = 235 cm, and back again: 3250 g = 3 kg 250 g.
More practice: Number line & rounding · Roman numerals · Mass percent vs volume percent