Calculating a price rise or fall in percentage terms

Understanding the subject

Percentage change compares the difference between two values with the starting value. The formula is: (new value divided by old value, minus one) multiplied by 100.

What it means in practice

For an illustrative move from 20 to 25, the rise is 25%. A return from 25 to 20 is a 20% fall. The starting point changes, so the percentages are not symmetrical.

Bring it into your next discussion

Before calculating antimony price movement, confirm that both observations use the same unit and market basis. An accurate formula applied to unlike numbers produces a misleading comparison.

• Match the units and underlying assessment basis.
• Use the earlier value as the denominator.
• Label the period and rounding used.