Understanding your form, list, and subscriber numbers in Hiro
Why don't my form submits match my subscriber growth?
A form submit means someone completed an on-site action. It doesn't automatically mean their email marketing consent changed.
A common assumption is that without double opt-in, every submission should count as a subscribe — that's not correct. Single opt-in only removes the confirmation-email step after someone subscribes. It doesn't mean every form is wired to write email marketing consent in the first place.
A few reasons the two numbers diverge:
Not every form field is a consent field. A submit can trigger a different underlying event — a back-in-stock alert, a referral entry, a giveaway entry — that has nothing to do with the marketing consent property.
Existing subscribers don't generate a new event. If the submitter is already an email marketing subscriber, the event doesn't fire again — it marks a change in consent, not a reaffirmation of it.
Optional consent checkboxes. If a form includes a marketing opt-in box that isn't required, the form still submits successfully whether or not it's checked.
Channel mismatch. A form can capture SMS consent without email consent, or the reverse, so a submit can register on one channel with no event on the other.
Duplicate or test submissions. The same person submitting more than once (fixing a typo, QA testing) adds to the submit count without adding a second subscribe event.
How does Hiro calculate Email Subscriber Growth?
Hiro's Email Subscriber Growth is calculated directly from Klaviyo's consent events:
Subscribed to Email Marketing − Unsubscribed from Email Marketing = Net growth
This measures explicit email marketing consent, account-wide.
The forms breakdown shows where subscribe events originated. It's not a full accounting of list growth, since people can also subscribe through checkout, manual import, or other non-form paths that Klaviyo may include in its own Subscriber Growth report.
Why does Klaviyo's own Subscriber Growth Report show a different number?
Klaviyo's native Subscriber Growth Report pulls from the same underlying Subscribed / Unsubscribed events, but applies its own reporting logic to subscriber status:
If someone subscribes and unsubscribes on the same day, Klaviyo's report doesn't count them as a new subscriber at all.
Klaviyo tracks consent and suppression as separate concepts — a profile can remain "subscribed" (consent) while being suppressed (undeliverable), so not every deliverability change maps to a subscribe/unsubscribe event.
Neither number is wrong. They're two different rulesets applied to the same event stream, which is why a gap between them is expected, not a sign of a tracking error.
Side-by-side comparison
Hiro: Email Subscriber Growth | Klaviyo: Subscriber Growth Report | |
|---|---|---|
What it counts | Net change in explicit marketing consent, account-wide | Klaviyo's own definition of a "new subscriber," applied to profile status |
Data source | Subscribed / Unsubscribed to Email Marketing events | Klaviyo's internal subscriber-status logic |
Known exclusion | None — every consent event counts | Same-day subscribe + unsubscribe is excluded from the new-subscriber count |
Consent vs. deliverability | Measures consent only | Tracks consent and suppression separately, so the total doesn't map cleanly onto consent either |