My Snapchat campaign is for reach, not sales: how do I calculate CPM and compare two creatives on it?

Why CPM and not cost per order for reach?

A reach campaign is optimised to show your ad to as many people as possible, not to bring orders. Judging it by cost per order is like judging a roadside billboard by how many people bought something while standing in front of it. What the platform was paid to deliver is impressions, so the fair question is what each thousand impressions cost. CPM also lets you compare two creatives that spent different amounts, because it divides spend by the volume of impressions.

Example: two creatives, 1,800 each

You ran two creatives in the same campaign, to the same audience over the same dates, and each spent 1,800 AED. There were no orders because selling was not the goal, so conversions went in as zero.

For a reach goal, creative A clearly wins: each thousand impressions cost 15 against 20, so the same budget got it seen more often. Creative B pulled more clicks, and its CPC of 1.6364 beats A's 2. That is worth knowing if you plan a traffic campaign later, but it is not what this campaign is judged on. Decide first what you are buying, then read the metric that measures it.

The steps in the calculator

1. From your Snapchat report, copy impressions and spend for each creative separately, over the same dates.
2. Open the Campaign performance calculator and enter creative A, with clicks if you want them and conversions at zero.
3. Read CPM, then press 'Copy result' to keep the figures before entering creative B, since the calculator shows one calculation at a time.
4. Enter creative B and compare the two CPMs.

What 'Undefined' means here

With zero conversions, CPA shows 'Undefined' along with the reason: spend cannot be divided by zero, and it does not mean conversions are free. Conversion rate shows 0% because there were clicks and no conversions, which is a correct result. In a reach campaign neither should worry you: set them aside and read CPM and CTR.

Keep in mind that the comparison is only fair between creatives on the same platform, audience and dates. CPM moves with the audience and the season, so comparing a creative that ran during Ramadan with one that ran in a quiet month measures the season, not the creative. When you later switch to a sales campaign, the ROAS calculator ties spend to revenue.