What is return on ad spend?

What does return on ad spend mean?

The usual formula is:

ROAS = revenue attributed to advertising ÷ advertising spend

If a campaign costs £5,000 and the chosen attribution method assigns £20,000 of revenue to it, ROAS is 4.0, often written as 4:1 or 400%. That means £4 of attributed revenue for each £1 of advertising spend.

Teams should agree whether “ad spend” means platform media cost only or includes creative and management fees. The conventional metric usually uses media spend, but the narrower boundary must be clear.

Attribution also matters. An advertising platform may claim revenue after a person viewed or clicked an advert within its selected window. Another analytics system may assign the same sale differently. ROAS therefore depends on both commercial results and measurement rules.

A return on ad spend example

A small online furniture retailer spends £3,000 on search advertising. Its reporting attributes £12,000 in sales to the campaign, giving a ROAS of 4.0.

If the products have a 35% gross margin, those sales create £4,200 of gross profit before fulfilment overhead, agency fees and other costs. Subtracting the £3,000 media spend leaves £1,200 before those remaining expenses. A 4.0 ROAS may therefore be healthy for one margin structure and inadequate for another.

If many customers later buy again, first-order ROAS may understate longer-term value. Conversely, generous attribution may overstate the campaign’s contribution.

Why does ROAS matter?

ROAS helps compare advertising activity when revenue can be linked reasonably to spend. It can inform budget allocation, bidding and investigation of changes in audience, offer or conversion.

It becomes more useful when viewed with gross margin, customer acquisition cost, incrementality and payback. Those measures prevent the team optimising attributed revenue while ignoring whether the advertising creates additional, profitable business.

A common ROAS mistake

Do not compare platform-reported ROAS values without checking attribution windows, included conversions and data sources. Two identical campaigns can appear different because the measurement settings differ.

Avoid setting one target ROAS across products with different margins or customer value. A lower initial ROAS may be acceptable for repeat-purchase customers, while a high-revenue, low-margin product may require more.

Do not assume attributed sales are incremental. Some people exposed to an advert would have bought anyway. Testing incrementality requires a suitable experiment or comparison, not another dashboard column.

Related terms and guides

• Return on investment: a broader comparison of profit or benefit with total investment.
• Customer acquisition cost: sales and marketing acquisition cost per new customer.
• Cost per click: advertising spend divided by paid clicks.
• Conversion rate: the proportion that completes a defined action.

Frequently asked questions

How do you calculate ROAS?

Divide revenue attributed to advertising by advertising spend. State the attribution method, timeframe and cost boundary beside the result.

Is a ROAS of 4 good?

Not necessarily. It depends on gross margin, other costs, customer lifetime value, cash flow and how accurately the advertising caused the reported sales.