Scale

Scale

Scale

What is a scale?

• For accurate drawings and constructions scale refers to a ratio

  • This ratio describes the relationship between the drawn size and the real-life size

• Maps are usually drawn to a scale

• The ratio will work for any unit of length applied to both sides

  • For example, the scale 1: 50 000 could mean 1 cm = 50 000 cm, 1 km = 50 000 km or even 1 yard = 50 000 yards

  • If you’re measuring the length from a map it will be easiest to measure in cm

How can I use a scale to find the actual lengths from an accurate drawing?

• STEP 1
  Use a ruler to measure the distance accurately on the map

  • For example, measuring a length from A to B as 5.8 cm

• STEP 2
  Use the scale to find the actual distance in the same units

  • For example, if the scale is 1 : 150 000 the actual distance = 5.8 cm × 150 000 = 870 000 cm

• STEP 3
  Convert the actual distance to a more suitable unit

  • For example, 870 000 cm = 8 700 m = 8.7 km

How can I use a scale to find lengths for an accurate drawing?

• STEP 1
  Convert the scale into a ratio where one side is 1 cm and the other side uses the units the real distance is measured in

  • For example, if the real distance is in km and the scale is 1 : 500 000,

  • 1 : 500 000 = 1 cm : 500 000 cm = 1 cm : 5 000 m = 1 cm : 5 km

  • So 1 cm on the map, represents 5 km in real life

• STEP 2
  Use this ratio to convert the actual distance to the scale distance

  • For example, if the actual distance = 20 km, the scale distance will be 20 ÷ 5 = 4 cm