10 Subreddits, 30 Ad Variants, One Afternoon: My ChatGPT Reddit Ads Workflow

Reddit Ads punish lazy targeting. Last quarter I ran a $2,100 weeklong test for a B2B SaaS client by mining ten niche subreddits, then feeding the threads to ChatGPT to get three ad variants per community — one per intent persona. Average CPM landed at $3.20, click-through hit 1.7%, and a single variant in r/devops paid for the whole test by the first Sunday. The workflow takes one afternoon. Here it is.

Step 1: Pull buying-intent threads, not topic threads

The recurring mistake on Reddit is targeting by topic. r/marketing has two million subscribers, and most of them are looking for jobs, venting about clients, or asking textbook questions. You want threads that smell like "I am about to spend money."

For each candidate subreddit, search inside it for these patterns: "vs" (e.g., "HubSpot vs Pipedrive"), "alternative to," "anyone tried," "cheap" or "pricing," "switching from," and "regret buying." Five to ten matching threads per subreddit is enough — paste the titles into a doc. I use Reddit's native search (subreddit:devops "alternative to"); GummySearch or a Reddit RSS feed both work too.

Step 2: Build a 10-subreddit shortlist with fit scores

Drop your candidate list and a one-paragraph product description into ChatGPT:

You are a paid-social strategist. For each subreddit below, score 1-5 on: (a) audience fit with this product, (b) density of buying-intent posts in the titles I'll paste, (c) tolerance for advertising on that sub. Output a table with a one-line reason per score.

Sub-10k-member subreddits often outperform 500k+ ones — Interteam's targeting data backs this up, and so do my own results. Start the filter at 1,000 members. Cut anything below a total of 9/15. You should land at exactly ten survivors; if you get twelve, keep the ten with the highest audience-fit scores, not the highest total.

Step 3: Extract three personas per subreddit

For each surviving subreddit, paste 5-10 buying-intent thread titles back into ChatGPT:

Cluster these into three buyer personas based on the intent expressed. For each persona, give me: the trigger event ("My CRM just raised prices 40%"), the desired outcome, and the dominant emotion (frustration, curiosity, fear of missing out).

Three personas per subreddit is the sweet spot. One is lazy, five over-fragments your budget.

Step 4: Generate 3 ad variants per subreddit

Feed the personas back, one subreddit at a time:

Write 3 Reddit promoted-post variants for [product] targeting r/[sub]. One per persona above. Use the subreddit's voice — no marketing speak, no exclamation marks. Headline ≤60 chars, body ≤200 chars. Each ad must reference the trigger event explicitly.

You'll end up with thirty variants. Spot-check each one: does it read like a redditor wrote it, or like a brand snuck into the feed? When it's the latter, regenerate with "rewrite this as if a frustrated user is recommending the tool." That single instruction fixes about 80% of the bad ones.

Step 5: Run the test — small, structured, boring

The structure that has held up across a dozen of my tests:

• One campaign, ten ad groups (one per subreddit)
• Three ads per ad group (your three persona variants)
• $30/day per ad group → $300/day total
• Run 7 days, kill anything below 0.8% CTR on day 4
• Keep your two best subreddits and two best variants, scale to $100/day each

$300/day for one week ($2,100 total) is the right size to actually learn something. Reddit's own SMB documentation suggests $500-$1,500/month as the floor; I prefer compressing that into a single decisive week so the signal doesn't get diluted across calendar noise.

What I'd do differently next time

Spin up a retargeting ad group from day one. Reddit's pixel is decent and I keep under-using it on first tests — even with zero conversions, by day three you have enough click traffic to retarget the curious-but-didn't-convert. That's the cheapest CPA in the whole funnel, and skipping it is the single mistake I've repeated across the last three Reddit tests.