Meta vs Google vs TikTok vs Reddit ads for ecommerce: where the next euro should go

Many platform comparisons in search results come from agencies that sell the service, such as one agency's Reddit and TikTok comparison pages¹². Ask how any figure in them was measured. A number without a method is an anecdote with a decimal point.

Platform-reported returns are also not comparable across platforms. A measurement vendor argues that platform ROAS can overstate some channels and understate others³. Meta's view of Meta against TikTok's view of TikTok compares counting, not results.

Google Ads shows ads to people searching, shopping and watching across Google's surfaces. Search and Shopping catch demand that already exists. Performance Max runs across Google's inventory from one campaign.

Meta (Facebook and Instagram) shows ads in feeds, stories and reels. It mostly creates demand: people were not looking for you when they saw the ad.

TikTok is short video first. The ad has to work as a TikTok, which means a steady supply of new creative. TikTok Shop is a separate thing: selling inside the app, with campaigns such as TikTok GMV Max.

Reddit is built around topic communities. For European shops, the public retail evidence we found comes from a study Reddit commissioned (see below). We know least about it, and we say so.

This is the criterion comparisons tend to skip. Before you add a channel, make sure its conversions can be deduplicated and compared with your orders. Otherwise you are adding a second opinion nobody can check.

Each platform sets its own attribution window: the time after a click or view in which a purchase is credited. Reddit's help centre describes its own click and view windows⁴. TikTok's help centre describes click-through, view-through and engaged view-through attribution⁵. Each platform counts with its own rules, so the same sale can be claimed by more than one of them.

On the tracking side, Reddit's help centre documents its own Conversions API⁶, and TikTok's Events API sends events from your server rather than the browser⁷. If a pixel and a server-side feed run together, you need event deduplication so one purchase is not counted twice. Without that plumbing, the platforms report and nobody can check.

Then add up what every platform claims for the month and compare it with what your shop actually sold. If the claims exceed the sales, the platforms are claiming some of the same orders.

Mostly the platforms. TikTok's business blog promotes a meta-analysis, run by TikTok's marketing science team with TransUnion, saying its ads drive incremental results⁸. Reddit has promoted retail results from a study it commissioned, as covered by trade media⁹. Both are platforms marking their own homework. That makes them a hypothesis, not a verdict.

The way to check is an incrementality test: switch the channel off for some people or regions, and compare. A holdout test or a geo test tells you what the channel adds, not what it claims.

If you already run Meta, Reddit is a test next to it, not a replacement. In a Shopify Community thread asking whether Reddit ads are worth it, the one substantive reply suggests putting a portion of the budget into Reddit alongside other channels and reviewing the data after several quarters¹⁰. A test, in other words. Decide in advance what result would make you keep it.

If Meta or Google are not paying, fix that first. More detail sits in reddit ads for ecommerce.

Both create demand. The difference is mostly creative. TikTok needs more video, more often, in the platform's own style, or you pay to show tired ads. Meta needs fresh creative too: creative fatigue sets in on every platform.

If you already sell inside TikTok, TikTok Shop changes the maths, because the sale happens in the app. That is a different service with its own economics.

Each channel can be bought separately. See Meta ads agency for ecommerce, Google Ads agency for ecommerce, TikTok ads agency for ecommerce brands, Reddit ads agency and TikTok Shop agency. Audits are free.