Return on ad spend: how to find your real break-even number

Aug 18
3 min read

Updated: 4 days ago

Introduction

Return on ad spend is revenue produced for every unit of currency spent on advertising. It is the most quoted number in paid media and one of the most frequently misread, because a healthy looking ROAS can still be losing money.

The problem is that the standard calculation uses revenue, and businesses pay their bills out of margin.

1. The basic calculation

ROAS = revenue from ads ÷ ad spend

Spend $1,000, generate $4,000, and ROAS is 4 — often written as 4x or 400%.

So far so simple. The difficulty is that this number has no inherent pass mark. A ROAS of 4 is excellent for one business and insolvent for another, and nothing in the figure tells you which.

2. Return on ad spend has to account for margin

Revenue is not what you keep.

At a 25% gross margin, $4,000 of revenue is $1,000 of gross profit. Against $1,000 of ad spend, you have broken exactly even while displaying a ROAS of 4.

Break-even ROAS = 1 ÷ gross margin

At 25% margin, break-even is 4. At 50% margin, break-even is 2. At 20%, break-even is 5.

Work out your own figure before reading any benchmark. Advice to "aim for 4x" is meaningless without knowing the margin it assumes.

3. Set a target above break-even

Break-even is not a target — it is the floor. Above it, you still have overheads, the cost of tools and time, and the fact that your margin estimate is probably optimistic.

A workable target is comfortably above break-even, with the gap sized to your fixed costs. If break-even is 4, a target of 6 leaves genuine room. A campaign running at 4.2 is not profitable in any way that matters; it is busy.

4. Judge on lifetime value where you can

ROAS measured on the first purchase understates campaigns that acquire customers who return.

If customers typically buy several times, a campaign at 2.5x on first purchase may be one of your best, because the same customer produces more later at no additional acquisition cost. Meanwhile a campaign hitting 6x from one-time buyers may be worse than it appears.

Where your data allows, calculate ROAS against the profit a customer produces over their whole relationship. It frequently reverses the ranking of your channels.

5. Watch what the platform is counting

Ad platforms report their own ROAS, and they are generous to themselves. Attribution windows mean a platform may claim a sale that another channel also claims — and both will show it.

Add the revenue each platform reports and compare it to your actual total. If the platforms claim more than you took, you know how much double-counting is present.

Your own sales figures are the ones to plan with.

6. When ROAS falls, diagnose before cutting

A declining ROAS has several possible causes, and they need different responses.

Creative fatigue shows up as falling click-through with stable conversion — the audience has seen it too often, so refresh the creative. Falling conversion with stable clicks points at the landing page or the offer, not the advert. Rising costs with everything else steady usually means competition or a seasonal shift.

Pausing a campaign because ROAS fell, without asking which of these happened, throws away whatever was still working.

7. Do not optimise ROAS in isolation

The simplest way to raise ROAS is to spend less on your least efficient audiences — which also shrinks the business.

A campaign at 10x on a tiny budget may be contributing less profit than one at 5x at scale. Total gross profit is the objective; ROAS is the efficiency check that stops you buying growth at a loss.

Conclusion

Calculate your break-even ROAS from your own gross margin, set a target above it that covers overheads, and measure against lifetime value where the data supports it.

Use your own sales numbers rather than the platform's, diagnose declines before pausing, and remember that efficiency is a constraint rather than the goal. The aim is the most gross profit you can buy above break-even — not the highest ratio.