If you're running Performance Max campaigns, your ads may now be appearing on Reddit. Not because you chose Reddit as a placement. Not because you decided Reddit audiences were right for your products. Simply because Google added it to the inventory available within PMax — and unless you've gone looking for it, you probably haven't noticed.

This is worth understanding, because it's a good example of how Performance Max works more broadly: Google expands placements over time, often without fanfare, and the default position is that your budget can be spent there unless you actively check.

What Reddit Inventory in PMax Actually Means

When Google includes Reddit in Performance Max, it means your ads can be served across Reddit's network — inside subreddit feeds, alongside discussions, and within Reddit's own ad placements. For users browsing Reddit on mobile or desktop, your products might appear as they're reading threads about hobbies, purchases they're considering, or communities they follow.

This isn't inherently bad. Reddit has a genuinely engaged user base and, importantly, a lot of very specific communities. A subreddit for home brewing has tens of thousands of members who are actively interested in the hobby — if you sell home brewing equipment, that's potentially useful inventory. A subreddit for mechanical keyboards has an audience that buys keyboards, switches, and accessories with real enthusiasm and real spending intent.

The issue isn't Reddit per se. The issue is not knowing it's happening.

Why It Matters — and Where It Gets Complicated

The value of Reddit as a placement depends entirely on what you sell and which communities your ads end up in. Google's algorithm determines where your ads appear based on signals about your products and the audiences most likely to convert. But the targeting is probabilistic, not precise.

A homeware business might find their ads appearing on home decor subreddits — genuinely relevant. Or they might find their budget spread across a much broader set of communities where the connection to their products is looser.

The transparency problem is this: you can't see which specific subreddits your ads appeared in. The placement report in Performance Max shows you domain-level data — so you can see that impressions appeared on reddit.com, but not which community, thread type, or section of the platform.

This means you're working with less granularity than you might want. You can see the domain; you can't see the context.

What You Can and Can't Control

This is where it gets a bit awkward.

You cannot exclude individual subreddits. If reddit.com is serving impressions and you'd rather it didn't, your options within PMax are limited. You can exclude reddit.com as a placement at the domain level — which will stop all Reddit inventory. Or you can exclude the "Content" network channel within your PMax campaign settings, which removes Display and Discover-style placements broadly.

The problem with the second option is that it doesn't only exclude Reddit — it removes the entire Content channel, which includes Google Display Network, Discover feed, and Gmail. If those placements are working well for you elsewhere, a blanket exclusion has collateral consequences.

There's no surgical option here. It's either accept Reddit as a potential placement, exclude the domain entirely, or exclude the whole Content channel.

Check Your Placement Report First

Before making any decisions, pull your placement report and see what's actually happening. In Google Ads, go to your PMax campaign, then Placements. You should see a list of domains where your ads have appeared.

Look for reddit.com in that list. If it's there, check the metrics:

  • What's the impression volume?
  • What's the click-through rate?
  • Most importantly — what conversions and conversion value is attributed to it?

A high impression count with zero conversions over 30 days tells you something. It might mean the placements are generating awareness but not purchase intent. Reddit users browsing communities aren't always in buy mode — they may see your ad, not convert, and potentially convert later through another channel without the attribution landing here.

That's not necessarily wasted spend, but it's worth knowing. If your overall campaign ROAS is strong and Reddit impressions are a small fraction of your total, it probably isn't worth losing sleep over. If you're seeing significant spend going to reddit.com with nothing to show for it in conversion terms, that's worth addressing.

The Broader Lesson About PMax Placements

Reddit is one example of a pattern that plays out regularly with Performance Max. Google adds new inventory sources, expands to new placements, and updates how the system allocates budget — and the default is always opt-in, not opt-out.

In the past year, PMax has extended into things like Search Partners, additional app inventory, and now Reddit. Each of these is potentially legitimate. Each of them also has the potential to absorb budget in ways that aren't obvious unless you're actively monitoring.

The practical implication is that running PMax well isn't just about setting it up once and checking your ROAS figure. It requires periodic review of where the money is actually going — which placements, which channels, which parts of the campaign are driving conversions versus impressions.

Placement reports give you domain-level visibility for Display and Discover inventory. Search Term reports (now partially available in PMax) give you some visibility into what queries you're matching. Asset group performance data tells you which creative combinations are working. Used together, these reports give you a reasonably clear picture of what's happening inside a campaign that's often described as a black box.

The algorithm is doing its job based on the signals it has. Your job is to make sure the signals are right, the structure is sensible, and you're not funding placements that don't serve your business goals.

Reddit may be excellent inventory for your products. Or it may not. The only way to know is to look.

If you want help reviewing your Performance Max campaign structure and placement performance, take a look at the Performance Max optimisation service for a full account audit.