SMS Opt-in Trend, Klaviyo

SMS Opt-in Trend for the selected period. The time-series of new SMS consent collected. This is the growth engine for the SMS list, and consent is the gate on everything else. How to read it, why it matters, and how to act on it.

Metrics type: Supporting Metrics • Category: Email Marketing

New SMS consent collected over time. Because you can only text people who opted in, this line is the ceiling on how far the whole SMS programme can grow.

At a glance

The time-series of new SMS opt-ins (consent) collected across the selected period, plotted as a line. Every SMS recipient must have explicitly agreed to receive texts under rules like TCPA and GDPR, so consent is the hard gate on the channel: you cannot send to anyone who has not opted in, and you cannot grow reach by importing a list. That makes this the single most strategic SMS card, because opt-ins are the growth engine for everything downstream: more consented contacts mean more reachable recipients, which means more sends, clicks, conversions, and revenue are even possible. A flat or falling opt-in line is an early warning that the programme is approaching its reach ceiling, regardless of how well your messages perform. Read it as the leading indicator for the channel: sends and revenue can only grow sustainably if this line is climbing.

What it counts	Net new SMS opt-ins (consent events) per period bucket, plotted as a line over the selected window.
API endpoint + statistics field	Consent and subscription metrics via GET /api/metrics and GET /api/metric-aggregates, aggregated per bucket for the SMS channel.
Email vs SMS aggregation	SMS consent only. Email subscriber growth is tracked separately under Subscriber Growth Rate.
MPP impact	None. Apple Mail Privacy Protection affects email opens only and has no bearing on SMS consent collection.
Chart type	Line.
Time window	30D vsP
Alert trigger	A sustained flattening or decline in new opt-ins against the recent baseline, which signals the SMS growth engine is stalling and reach will soon plateau.
Roles	owner, marketing

Calculation

Calculated automatically from your Klaviyo data. See the At a glance summary above for what the metric tracks and the worked example below for a typical reading.

Worked example

An illustrative outdoor-gear brand that added an SMS sign-up incentive to its checkout and a keyword opt-in to a campaign. Reading the dashboard on 14 Apr 26 for the trailing 30 days (14 Mar 26 to 12 Apr 26), the SMS opt-in line by week looks like this (illustrative figures):

Week	New SMS opt-ins	Running consented list
14-20 Mar 26	210	12,400
21-27 Mar 26	230	12,630
28 Mar-3 Apr 26	540	13,170
4-12 Apr 26	610	13,780

Baseline opt-ins ~220 per week, then weeks 3 to 4 jump to ~575
The lift coincides with the checkout incentive and keyword campaign going live
List grew from 12,400 to 13,780, roughly +11% over the window

Five observations:

1. The line steps up sharply in weeks 3 and 4. Opt-ins more than doubled from the ~220 baseline to ~575 per week. That step is the signature of a new acquisition source going live, here the checkout incentive and a keyword campaign.
2. This growth is the precondition for every other SMS number rising. A bigger consented list raises the ceiling on sends, clicks, conversions, and revenue. None of those can grow sustainably while this line is flat, which is why it is the leading indicator.
3. Consent is the gate, not a nice-to-have. Every one of these opt-ins is a contact you are now legally permitted to text under TCPA and GDPR. You cannot shortcut it by importing numbers, so the only path to more reach is more genuine opt-ins.
4. Quality of source matters, not just count. Opt-ins captured at checkout or via an explicit keyword tend to be high-intent and convert well. Watch this line alongside SMS Conversion; a growth spike that does not lift conversion may be lower-quality consent.
5. A flattening line is an early plateau warning. If opt-ins stall while you keep sending, you are working a fixed audience harder, which lowers revenue per send over time. The fix is to add or refresh acquisition sources, not to send the same list more often.

Sibling cards merchants should reference together

SMS Opt-in Trend is the growth engine for the channel. Pair it with these:

Card	Why pair it with SMS Opt-in Trend
Subscriber Growth Rate	The email growth counterpart. Read them together to see how both consented audiences are trending.
Active Subscribers	The size of your engaged audience. New opt-ins feed it, so a rising opt-in line should show up here over time.
SMS Overview	The cockpit view. Opt-in growth is the lead indicator behind the overview’s sends and revenue.
SMS Sends	The reach this growth enables. Send volume can only scale as far as the consented list allows.
SMS vs Email Sends	The channel-mix view. Faster SMS opt-in growth supports shifting more reach toward SMS over time.

Reconciling against Klaviyo

Where to look in Klaviyo:

• Klaviyo → Audience, then the SMS consent view, where opted-in profiles and consent status are listed.
• Klaviyo → Analytics → Metrics, then the SMS subscription or consent metric over time, for a per-bucket count of new opt-ins.
• Klaviyo → Sign-up forms and Klaviyo → Flows, to attribute opt-ins to specific acquisition sources.

Why our number may legitimately differ:

Reason	Direction of divergence
Net vs gross. This line tracks net new opt-ins per bucket. A gross view that ignores same-period opt-outs will read higher.	Ours can read lower than a gross-only view.
Time zone. Vortex IQ buckets by UTC day; Klaviyo uses your account time zone. An opt-in near midnight can fall into a different period.	Either direction, usually marginal.
Consent state definitions. Pending or double-opt-in confirmations may be counted at a different stage between a live Klaviyo view and our snapshot.	Either direction.
Source scope. A view scoped to a single sign-up form will read lower than our all-source total.	Ours reads higher than a single-source view.
Period boundaries. Vortex IQ uses a 30-day rolling window vs prior; Klaviyo dashboards often default to calendar months.	Either direction.

Known limitations / merchant FAQs

Why is opt-in growth so important for SMS specifically? Because consent is the gate. You can only legally text people who explicitly opted in, and you cannot import or buy your way to more reach. So unlike email, where reach can grow several ways, SMS reach grows only through opt-ins. This line is the ceiling on the whole channel.

What counts as an opt-in here? A profile giving explicit SMS consent, captured through a sign-up form, a checkout consent box, a keyword text, or another compliant source. The exact moment of counting depends on whether your account uses a confirmation step, which can shift a profile between pending and confirmed consent.

My opt-in line is flat, what should I do? Add or refresh acquisition sources. A flat line means the channel is approaching its reach ceiling, and sending the same list harder lowers revenue per send. Common levers are a checkout consent prompt, a sign-up incentive, and keyword campaigns. The aim is more genuine consent, not louder broadcasts.

Does a falling line mean people are opting out? Not directly. This line tracks new opt-ins. A fall means fewer people are joining, which is different from people leaving. Net new is opt-ins minus same-period opt-outs, so heavy opt-outs can pull the net figure down, but the primary signal here is acquisition slowing.

Are all opt-ins equally valuable? No. Consent captured at high-intent moments, such as checkout or an explicit keyword, tends to convert better than consent from a generic pop-up. Watch this line alongside SMS conversion to judge the quality of new opt-ins, not just the count.

Does this include email subscribers? No. This card tracks SMS consent only. Email subscriber growth is a separate metric. Keeping them apart matters because email and SMS consent are legally and behaviourally distinct.

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Tracked live in Vortex IQ Nerve Centre

SMS Opt-in Trend is one of hundreds of KPI pulses Vortex IQ tracks across Klaviyo and 70+ other ecommerce connectors. Nerve Centre runs the detection layer; Vortex Mind investigates the cause when something moves; Ask Viq lets you interrogate any number in plain English.

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