ToolSahla, Tools Sahla

I paused my ads but sales kept coming in: why does the ROAS calculator show undefined instead of an infinite return?

Because ROAS is revenue ÷ spend, and dividing by zero has no result in maths. The calculator writes 'Undefined' on purpose so it never suggests an infinite return. Sales that arrived with no spend are not a return on ads; they are organic or repeat sales, and they are worth reading another way.

Published · 3 min read

What the calculator shows

In the ROAS calculator, enter the sales from the month the ads were off, say 4,200 AED, and a spend of zero. You will see:

  • ROAS as a multiplier and as a percentage: Undefined, greyed out.
  • Ad spend as a share of revenue: 0%, which is correct, since the ads took nothing from sales.
  • A notice saying ROAS is undefined because spend is zero, and that this does not mean an infinite return.
  • If you add a margin, say 35%, a break-even ROAS of 2.86x and an estimated profit of 1,470 appear, but no above or below verdict, because there is no ROAS to compare.

The estimated profit here is simply 35% of 4,200: gross profit on the sales, with no ad cost taken off.

Why not just say 'infinite'?

Divide by a tiny spend, such as a single dirham, and ROAS comes out at 4,200x. Move closer to zero and the number grows without limit. Showing that as an infinite return would suggest the ads were at their best, when in fact there were no ads. Those sales were not bought by advertising, so crediting them to it makes no sense.

What the sales that kept coming tell you

This is where a pause earns its keep. Say that the month before, your store sold 15,000 AED in total and spent 3,000 AED on ads, a whole-store ROAS of 5x. Then you paused the ads and sales held at 4,200 AED.

  1. Sales that continued without ads: 4,200. That baseline may well have been there in the ad month too.
  2. The increase that came with the ads, roughly: 15,000 − 4,200 = 10,800.
  3. Enter 10,800 as revenue and 3,000 as spend: ROAS is 3.6x rather than 5x. At a 35% margin it is still above the 2.86x break-even, but estimated profit is 780 instead of 2,250.

It is a rough calculation: the two months differ in season, promotions and number of days, and some quiet-month sales may be a delayed effect of earlier ads. But it gives you a realistic sense that part of the sales platforms credit to your ads might have happened anyway.

Putting it to use

  • Do not base a budget decision on a single paused month. Repeat the comparison over more than one period if you can.
  • Separate ad-driven sales with tagged links from the UTM campaign link builder, so they are easier to tell apart from organic ones.
  • If a large share of sales carries on without ads, review each campaign from click to order in the Campaign performance calculator before switching it back on at the same budget.

Common questions

Does 'Undefined' mean I entered something wrong?

No. Your input is fine; the result only means that division by zero has no answer.

Why is the ad share 0% and not undefined?

Because it divides spend by revenue, and revenue here is above zero. Zero divided by 4,200 is zero.

So how do I measure ad return for the paused month?

There is no ad return for a month with no ads. Compare a month with ads against one without, as in the example.