5. Scales

Natural increments

Use natural increments for your x-axis and y-axis scales.

Examples include:

• 0, 1, 2, 3, 4, 5
• 0, 2, 4, 6, 8, 10
• 25, 50, 75, 100
• 0, 100, 200, 300,400
• 0, 1,000, 2,000, 3,000

Abbreviating forms

Use the most significant increment when using abbreviated forms.

Common abbreviated forms include:

Number	Abbreviation
Thousand	K
Million	M
Billion	B
Trillion	T

Minimum and maximum axes boundaries

For line charts, variation is best shown when the y-axis is set to a non-zero value. For example, Figure 5.1 shows a time series of energy consumption in Spain. The minimum y-axis value is set to zero. However, the lowest value in the data set is around 5.6 tons, whereas the highest is 6.2 tons. A zero baseline makes it difficult to see variation between these values.

Figure 5.2 shows the same data as above, but the minimum value of the y-axis was changed from 0.0 to 5.0. It is much easier to see the changes over the years.