Use the formula `=ABS(A1-B1)/AVERAGE(A1,B1)`
Format the result cell as Percentage
If comparing a new value to an old value, use `=(B1-A1)/A1`
Format the result cell as Percentage
To show only the magnitude of change, use `=ABS((B1-A1)/A1)`
Format the result cell as Percentage
Replace `A1` and `B1` with the cells you want to compare