In forceMetricsIn force 23 Sep 2025Verified 1 Aug 2026

Klaviyo holdout groups need 400,000 profiles

Q: How do I measure email incrementality in Klaviyo?

Klaviyo ships native holdout groups free, and they are the methodologically correct way to answer whether your email caused the revenue. They require at least 400,000 total profiles, apply across all channels at once, allow only one active holdout, and the percentage cannot be changed once set.

Q: In plain English?

Holdout groups are how you prove email caused revenue instead of taking credit for people who would have bought anyway. Klaviyo offers holdouts free above a large profile threshold (~400k). Smaller brands need another method (manual holds, geo splits, careful tests) or they should stop overstating causal lift.

How do I measure email incrementality in Klaviyo?

Global · Tool: Klaviyo

How email works

In one sentence

Honest email lift needs — Klaviyo’s free holdout tool needs about 400,000 profiles; most brands are under that.

Emailrules interpretation

groups are how you prove email caused revenue instead of taking credit for people who would have bought anyway. Klaviyo offers holdouts free above a large profile threshold (~400k). Smaller brands need another method (manual holds, geo splits, careful tests) or they should stop overstating causal lift.

Why it matters. Without , “email revenue” is often correlation. Finance will eventually notice.

Dotted words open definitions. See how email actually works.

What to do

Your move — not a lecture

Good to know — nothing to fix

Changes a number you report or a risk you carry, not today's task list.

Nothing to configure unless you clear the threshold, and if you are under it there is genuinely no workaround inside the platform.

Your part: Being honest about it. Under the threshold, attributed revenue is an estimate, and calling it incremental in a board deck is the kind of thing that gets found out.

What to do first

Check your profile count. Over 400,000, switch it on, it costs nothing. Under, stop using the word "incremental" about attributed revenue.

You can skip this if: You are not on Klaviyo.

Who this applies to

Every brand under 400,000 profiles has no incrementality measurement available at all. Above it, you get one account-wide, all-channel , never per flow.

Checklist

01If you clear 400,000 profiles, turn it on. It is free and it is better than any estimate.
02Choose the percentage carefully, because it is immutable.
03Below the threshold, be honest that attributed revenue is an estimate, and do not present it as causal.
04Note that the specialist incrementality vendors, Haus, Measured and INCRMNTAL, do not cover email as a channel.

That’s enough to act. The exact wording, the enforcement record and the primary source sit under Proof & sources, for counsel, bosses, or AI tools that need a citation. Not legal advice.

Proof

Exact position, enforcement, sources

For records and people who will check you. Skip if Monday’s move is already clear.

Source fact

Klaviyo ships native groups free, and they are the methodologically correct way to answer whether your email caused the revenue. They require at least 400,000 total profiles, apply across all channels at once, allow only one active holdout, and the percentage cannot be changed once set.

What happens if you do not

Not enforced. It is a product gate, and it is the reason most brands cannot answer the most important question they have.

Source

Klaviyo, Getting started with global holdout groups
Published 23 Sep 2025Read primary source

History of this page

1 Aug 2026Correction: the source was cited with the wrong title and a placeholder date. Klaviyo's page is 'Getting started with global holdout groups', last updated 23 Sep 2025. The effective date was corrected to match.
28 Jun 2026Added.

Klaviyo counts Apple machine opens toward revenue by defaultIn force

Take this with you

GET https://emailrules.today/rules/klaviyo-holdout-group-400k-gate?format=json

Same URL, same answer, every field including the ones behind the Proof tab. An Accept: application/json header on the plain URL does the same thing. All the endpoints.