Your ad was working last month. This month, the same ad costs more per sale. You haven't touched it.
Usually that's ad fatigue. The people you keep reaching have seen it enough times that they scroll straight past.
Think about the song that was everywhere last summer. You liked it for two weeks. Now you skip it in the first three seconds. Same song, and you're the one who changed.
How to tell it's fatigue
Open Ads Manager and compare the ad with itself over time. Three numbers tell you most of the story.
Frequency is how many times the average person has seen the ad. Click-through rate is how many of them click. Cost per purchase is what you pay for each sale.
Fatigue looks like this: frequency climbs, click-through rate slides, and cost per purchase goes up, all at about the same time.
You'll find blogs promising a magic frequency number. I wouldn't trust one. A big audience and a tiny audience tire at different speeds, and so does a ₹500 product compared with a ₹15,000 one. Your own ad's history is a better guide than anyone's rule.
When it looks like fatigue and isn't
If people are still clicking at the same rate but fewer of them buy, the ad is doing its job. Something changed after the click. Maybe the page got slower, the price went up, your best size sold out, or checkout broke on some phones.
New creative won't fix any of those. You'd spend money making ads for a problem that lives on your website.
So before you brief a new ad, buy from your own store on your phone, starting from the ad.
What to do about it
Change the idea, more than the colours.
A new background on the same message still looks like the same ad to someone who's tired of it. Try a different reason to buy instead. Show the problem the product solves, a customer's objection answered, or the product being used by someone real.
Test one new angle at a time, so you know which one did the work. If your budget is small, run fewer ads. Three ads sharing a tiny budget will all struggle to learn anything.
And don't switch off an ad just because you're bored of it. You've seen it a thousand times. Your customer hasn't. Let the numbers tell you when it's tired.
Not sure if it's the ad or the store? Book a free 15-minute audit call and I'll show you where people are dropping off.