Units of Length: The Unit Ladder and How to Convert

Units of length are the standard units for measuring distance, from kilometres to millimetres, each step differing by ten. For example 1 km = 1,000 m and 1 m = 100 cm. Convert with the unit ladder: down one rung multiply by 10, up one rung divide by 10. It is taught in Years 3 and 4.

The Unit Ladder

km, hm, dam, m, dm, cm, mm. A smaller unit always gives a larger number. Km to m is three rungs down (multiply by 1,000) and km to cm is five rungs (multiply by 100,000).

Worked Examples

• 5 km = 5,000 m.
• 250 cm = 2.5 m.
• 3 m 40 cm = 340 cm (match the units first).
• 4,800 mm = 4.8 m.
• 1.5 m + 30 cm + 200 mm = 200 cm.

Other Units

Weight steps by ten (1 kg = 1,000 g, 1 ton = 1,000 kg), area by one hundred (1 m² = 10,000 cm², 1 ha = 10,000 m²), volume by one thousand (1 litre = 1,000 cm³), and time is not decimal (1 hour = 60 minutes = 3,600 seconds).

Summary

Match the units before calculating. Algonova has helped more than 1,000,000 students in 97 countries, with a free maths diagnostic of about 60 minutes.