Reddit Lookalike Audiences: Build and Target Them (2026)
Reddit Lookalike Audiences are targetable groups of Reddit users who behave like a source audience you provide, such as your customers, site visitors, or high-engagement users. Reddit builds them by finding users with similar interest and behavior patterns, so you can reach new people who resemble your best audiences instead of only retargeting the ones you already know.
What Are Reddit Lookalike Audiences?
A Reddit Lookalike Audience is a prospecting audience derived from a source audience you already have. You give Reddit a custom audience, such as people who bought from you or who engaged with your community, and Reddit finds a broader set of users whose on-platform behavior looks like that source. The result is a targetable group of new users, not a copy of the people you already reached.
This sits between retargeting and broad interest targeting. Retargeting reaches people you already know. Interest targeting reaches anyone in a topic. A lookalike reaches people you do not know yet but who act like the customers you do know, which is usually a better balance of relevance and scale than either extreme.
How Do Reddit Lookalike Audiences Work?
Reddit uses its own signals, such as the communities a user joins, the posts they read and vote on, and their ad engagement, to model similarity to your source audience. When you create the lookalike you choose how closely it must match: a tight match mirrors your source closely and stays small, while a broad match trades some similarity for much larger reach.
Because the lookalike is generated from your first-party data, its quality depends on the source. A lookalike built from high-value customers will behave differently from one built from all site visitors. The source audience is the input that decides who the lookalike finds.
What Source Audiences Can You Use?
Lookalikes are built from a Reddit Custom Audience. The common custom audience types are a customer list you upload (hashed emails or phone numbers), website visitors collected through the Reddit Pixel, app users from app events, and engagement audiences of people who interacted with your Reddit ads or community.
You need a healthy source before the lookalike is useful. Reddit recommends a source audience with enough records to model from; a tiny or low-quality source produces a lookalike that resembles noise more than your best users. Build the custom audience first, let it accumulate, then create the lookalike from it.
How Do You Create a Reddit Lookalike Audience?
Open the Audiences section of the Reddit Ads dashboard and create a Custom Audience first if you do not have one. Then create a new audience and choose the Lookalike option, or select "build a lookalike" from an existing custom audience. Pick the source audience, name the lookalike, choose the location, and select the match level from tight to broad.
After it builds, apply the lookalike as a targeting audience in a new or existing campaign, just like any other Reddit audience. Keep it as a prospecting layer separate from your retargeting campaigns so you can read its performance without mixing known and new users.
How Should You Size and Tune a Lookalike?
Start with a tight match. A tight lookalike is the most similar to your source and therefore the safest test of whether the modeling works. If delivery is too small or costs are too high, widen the match level to add reach. Treat the match level as a dial between precision and volume.
Also watch the source. If a tight lookalike underperforms, the problem is often the source audience, not the lookalike settings. Refresh the source with your most recent high-value customers, or split it so the lookalike is modeled on buyers rather than all visitors. The source audience is the lever that matters most.
How Do Lookalikes Compare with Other Reddit Targeting?
Subreddit targeting asks you to pick the communities your buyers read, which works when you know the right subreddits but misses adjacent ones. Interest targeting casts a wide topical net with no first-party signal. Retargeting reaches people already in your funnel. A lookalike adds your own data to Reddit's scale: it finds users similar to your customers across the whole platform, not just inside the subreddits you named.
The practical play is to layer them. Use a lookalike for top-of-funnel reach, retargeting for bottom-of-funnel follow-up, and subreddit or interest targeting for thematic relevance. Keep the lookalike on prospecting campaigns so its job is purely to find new users.
Measuring Lookalike Performance
A lookalike is only worth running if it finds new customers more efficiently than broad interest targeting. Judge it on the same outcomes you use for any prospecting campaign, but read it separately from retargeting so the numbers are not blurred by known users. Reddit's Ads Manager reports CPA and ROAS at the ad-group level, so keep each lookalike in its own campaign to see its true contribution.
Watch these signals during the first two weeks:
- New-user rate: The share of conversions from people outside your custom audiences. A healthy lookalike should be 70% to 90% net-new.
- Cost per acquisition (CPA): Benchmark against your retargeting CPA; a lookalike running within 1.5x of retargeting CPA is strong.
- CTR and CPC: Compare them to your interest campaigns. Higher CTR implies the model found relevant users.
- Conversion lag: Lookalike users often convert 3 to 7 days after the click, so wait a full week before judging.
- Frequency: Cap at 3 to avoid burning the prospecting pool with repeat impressions.
Run a holdout by holding back 10% of the lookalike audience and comparing conversion lift. If lift is near zero, the source audience is too similar to everyone on Reddit and needs a tighter, higher-value definition.
Common Lookalike Mistakes
Most failing lookalike campaigns break on the source audience, not the settings. Avoid these errors:
- Building from a tiny source: A source under roughly 1,000 records models noise. Accumulate customers or pixel visitors before creating the lookalike.
- Using a mixed source: Modeling on "all site visitors" pulls in browsers who never buy. Model on buyers or demo requests instead.
- Starting broad: A broad match buries the similarity signal. Start tight, then widen only if delivery is weak.
- Mixing prospecting with retargeting: Putting a lookalike in the same ad group as a custom audience hides which one drove results.
- Letting the source go stale: Last quarter's customers behave differently from this quarter's. Refresh the source monthly.
- Expecting instant conversions: Lookalikes warm users up; pair them with retargeting to close the sale.
A Practical Lookalike Launch Checklist
Use this sequence before spending on a new lookalike:
- Confirm a custom audience with at least 1,000 high-value records exists and is populating.
- Name the lookalike by source and match level (e.g., "Buyers - Tight") so reporting stays clear.
- Choose tight match for the first test; widen only after 7 days of data.
- Place it in a dedicated prospecting campaign, isolated from retargeting.
- Verify the Reddit pixel or server-side events API is recording conversions before launch.
- Set a frequency cap of 3 and a 14-day minimum learning window.
- Define a stop-loss CPA (e.g., 2x target) and a weekly 30-minute review to reallocate budget.
Following this checklist keeps the lookalike accountable to real acquisition math instead of platform novelty, and it makes the next lookalike easier to tune because you will already know your baseline CPA.
Key Takeaways
- A Reddit Lookalike Audience reaches new users who behave like a source audience you provide.
- It is built from a Reddit Custom Audience such as a customer list, pixel visitors, or engagers.
- Choose a match level from tight to broad to balance similarity against reach.
- Use lookalikes for prospecting and keep them separate from retargeting campaigns.
Frequently Asked Questions
What Are Reddit Lookalike Audiences?
Reddit Lookalike Audiences are targetable groups of Reddit users who behave like a source audience you provide, such as customers or engagers. Reddit models similarity from its own platform signals and returns a broader set of new users who match that source.
What Source Audience Do I Need for a Reddit Lookalike?
You need a Reddit Custom Audience first, such as a customer list upload, website visitors from the Reddit Pixel, app event users, or an engagement audience. The lookalike is derived from that source, so its quality depends on the source's size and value.
How Do I Create a Reddit Lookalike Audience?
Open the Audiences section of the Reddit Ads dashboard, create or pick a Custom Audience as the source, then create a Lookalike from it. Set the name, location, and match level from tight to broad, then apply it as a targeting audience in a campaign.
Should I Use a Tight or Broad Reddit Lookalike?
Start tight for the closest match to your source and the safest test, then widen the match level if delivery is too small or costs are too high. The source audience quality matters more than the match setting, so keep it refreshed with your best customers.
How Are Reddit Lookalikes Different from Retargeting?
Retargeting reaches people you already know, such as site visitors or engagers. A lookalike reaches new users you have never touched who behave like those known people. Use lookalikes for prospecting and retargeting for bottom-of-funnel follow-up.