How do you convert ACOS to ROAS?
Divide 100 by the ACOS: ROAS = 100 ÷ ACOS. An ACOS of 25% is a ROAS of 4, and an ACOS of 20% is a ROAS of 5.
It works because the two are the same ratio turned upside down: ACOS is ad spend ÷ ad sales, ROAS is ad sales ÷ ad spend. The 100 only turns the percentage back into a plain ratio.
ROAS = 100 ÷ ACOS (in %)
How do you convert ROAS to ACOS?
Divide 100 by the ROAS: ACOS = 100 ÷ ROAS. A ROAS of 5 is an ACOS of 20%, and a ROAS of 2 is an ACOS of 50%.
A ROAS of 1 is an ACOS of 100%: the ads brought in exactly what they cost. Below a ROAS of 1, the ACOS goes above 100%.
ACOS (in %) = 100 ÷ ROAS
ACOS to ROAS conversion table
The ROAS each common ACOS equals, rounded to two decimals the way Amazon displays ROAS.
| ACOS | ROAS |
|---|---|
| 5% | 20.00 |
| 10% | 10.00 |
| 15% | 6.67 |
| 20% | 5.00 |
| 25% | 4.00 |
| 30% | 3.33 |
| 35% | 2.86 |
| 40% | 2.50 |
| 50% | 2.00 |
| 60% | 1.67 |
| 75% | 1.33 |
| 100% | 1.00 |
ROAS to ACOS conversion table
The ACOS each common ROAS equals.
| ROAS | ACOS |
|---|---|
| 1.00 | 100% |
| 1.50 | 66.67% |
| 2.00 | 50% |
| 2.50 | 40% |
| 3.00 | 33.33% |
| 4.00 | 25% |
| 5.00 | 20% |
| 6.00 | 16.67% |
| 8.00 | 12.5% |
| 10.00 | 10% |
ACOS vs ROAS: which one should you use?
Either: they carry exactly the same information, and Amazon reports both. Use the one your goal is written in.
Sellers and authors often think in ACOS, because it compares directly with their margin: the break-even ACOS is the margin before ads. Brands and agencies used to Google or Meta ads often think in ROAS.
Mind the direction: a lower ACOS is better, a higher ROAS is better. And they do not move evenly: going from a ROAS of 4 to 5 takes the ACOS from 25% to 20%, but going from 2 to 3 takes it from 50% to 33.33%.
What is a break-even ROAS?
Your break-even ROAS is the lowest ROAS at which ads still pay for themselves: 100 divided by your profit margin before ads, in percent. With a 30% margin, it is 3.33.
Below that ROAS, the ads cost more than the profit their sales leave. It is the same point as the break-even ACOS (here 30%), written the other way round.
Break-even ROAS = 100 ÷ margin before ads (in %)