It uses the same percentage change formula as any other comparison, but applied specifically to values that are **one year apart**.
YoY change = (This year’s value − Last year’s value) / Last year’s value × 100
Why YoY instead of month‑over‑month?
Month‑over‑month comparisons (like March → April) can be misleading for businesses with **seasonal patterns**.A toy store’s April revenue will naturally differ from its December revenue — even if the business is growing — simply because demand changes seasonally.
Comparing **March this year to March last year** removes that seasonal noise and reveals the underlying trend.
YoY is ideal for:
- retail with seasonal peaks
- tourism and hospitality
- agriculture
- quarterly business reporting
- any dataset with predictable seasonal cycles
Worked example: quarterly revenue
A company’s Q2 revenue was $840,000 last year and $945,000 this year.What is the YoY percentage change?
Step 1:
Last year’s value = 840,000
This year’s value = 945,000
Step 2:
(945,000 − 840,000) / 840,000 × 100
= 105,000 / 840,000 × 100
= 12.5
Step 3:
Revenue grew **12.5% year‑over‑year** in Q2.
A note on comparing percentages
If you compare two YoY growth rates themselves — for example:- 12.5% YoY this quarter
- 9% YoY last quarter
— the difference between them is measured in **percentage points**, not percent.
For a refresher, see percentage points vs percentage change.
Ready to calculate your own YoY numbers? Use the percentage change calculator with last year’s and this year’s values.