This one gets decided by a question nobody phrases correctly. It is not which sends better marketing email, because both send it perfectly well. It is what your email is allowed to know. SendGrid's marketing product operates on contact lists with custom fields — a reasonable model that has served a great many businesses. Klaviyo operates on profiles assembled from a live feed of store events, so the message can react to what somebody did an hour ago. If your email does not need to react to anything, you are about to overpay dramatically.
At a glance
| Klaviyo | SendGrid | |
|---|---|---|
| What it is | Ecommerce marketing automation | Twilio's email platform — API, SMTP, and marketing |
| Published pricing | $30/mo at 1,000 profiles, $100 at 5,000, $150 at 10,000, $720 at 50,000, and $1,380 at 100,000 — an effective $0.014–0.030 per profile per month. | Essentials $19.95 at 50K and $34.95 at 100K. Pro $89.95 at 100K, $249 at 300K, $499 at 700K. Dedicated IP is Pro and above; extra IPs $30/mo. Marketing Campaigns is priced as its own plan, not an add-on. |
| Best for | Ecommerce, especially Shopify, where per-campaign revenue attribution is the metric. | Enterprises wanting one procurement relationship, SMTP everywhere, and marketing in the same console. |
| Watch out for | Bills all active profiles since February 2025 and auto-upgrades without ever auto-downgrading. Volume is capped at ten times your profile count and sends halt past it. | The free tier died on 27 May 2025, replaced by a 60-day trial at 100/day. Support latency and abrupt account suspensions dominate its public reviews. |
Prices are each vendor's published list prices, verified August 2026. Check the vendor's own page before you sign anything.
Where they actually differ
What the system knows about a person
Klaviyo
A profile assembled from a continuous feed of store activity: products viewed, carts started and abandoned, orders placed, revenue to date, time since last purchase. The data model was designed for commerce and it arrives without anybody writing an integration, which is why a segment like browsed this category twice and has not ordered in sixty days is a few clicks rather than a project.
SendGrid
A contact with custom fields you define and populate yourself. It is a flexible and honest model, and it means every behavioural attribute in your emails exists because somebody built a pipeline to put it there and keeps that pipeline running. For a business whose segmentation is genuinely list-shaped — customers, trial users, newsletter subscribers — that is not a limitation.
Showing that the channel paid for itself
Klaviyo
Attribution is the actual product. Klaviyo ties orders back to the message that preceded them and reports revenue per campaign and per flow, which is the number a store owner uses to justify the subscription. The attribution windows are configurable and generous, so treat the headline figure as directional rather than as a controlled experiment, and the direction is usually right.
SendGrid
You get opens, clicks and deliveries, and connecting those to money is your own work — export the events, join them against orders in your warehouse or analytics tool, and maintain that join. Some teams do this well and end up with a more honest number than any vendor's default attribution. Most teams do not do it at all, and therefore cannot say what the channel is worth.
What the meter counts
Klaviyo
Active profiles, billed whether or not you ever message them, with a volume allowance pinned at a multiple of the profile count. Two consequences follow and both surprise people: signups you never email still raise the invoice, and the plan auto-upgrades when profiles grow without ever auto-downgrading when they shrink. Pruning the list is a billing activity, not just a hygiene one.
SendGrid
Sending volume, on a plan ladder. The marketing product is priced as its own plan rather than bundled with the transactional one, so the one-vendor story is two subscriptions. A dormant contact costs nothing until you mail it, which is the better shape for a business with a large, quiet list and the worse shape for one that mails a small list constantly.
Transactional mail on the same account
Klaviyo
Klaviyo is a marketing platform and its transactional story is thin. Order confirmations and shipping notices generally come from the store platform or a separate sending vendor, which is the normal arrangement and means Klaviyo is an addition to your stack rather than a consolidation of it.
SendGrid
This is SendGrid's real advantage in the pair. The API, the SMTP relay and the marketing product live under one account with one vendor relationship, so receipts, password resets and campaigns are one procurement conversation. Keep them on separate subdomains anyway, because sharing a vendor is fine and sharing a sending reputation is not.
Building a multi-step sequence
Klaviyo
Flows are the half of Klaviyo that earns the money: triggered by store events, branching on profile attributes and behaviour, with waits, splits and back-in-stock or abandoned-cart templates that arrive pre-built. A merchant can assemble a working abandoned-cart sequence in an afternoon without engineering help, and that is the specific capability people are buying.
SendGrid
Automations exist and are list-and-trigger shaped rather than behaviour shaped: a welcome series, a date-based sequence, a send when somebody joins a list. It covers a great deal of ordinary marketing. What it does not do easily is react to something that happened in your product ten minutes ago, unless you built the pipeline that tells it.
Where the store data comes from
Klaviyo
Native integrations with the major commerce platforms, Shopify most deeply, syncing catalogue, customers and orders both directions without an engineer. That depth is why the evaluation is frequently over before it starts for a Shopify merchant, and it is worth noticing that it is also what makes leaving expensive later.
SendGrid
An API and a contacts import, plus whatever middleware you choose to run. Everything is possible and nothing is automatic. For a business with an engineering team and an existing data warehouse this is sometimes preferable — the pipeline is yours, the definitions are yours, and no vendor is guessing what a customer is.
Sending for several brands or clients
Klaviyo
Klaviyo's model is one account per store, and agencies manage a collection of accounts rather than tenants inside one. That is a coherent arrangement for merchants and an administrative cost for anybody operating at portfolio scale.
SendGrid
Subusers are the strongest structural feature SendGrid has: each gets its own credentials, reputation, suppression and reporting under one parent account. If you send on behalf of customers, this alone often decides the evaluation, and there is no comparable concept on the other side of this pair.
Who is responsible when mail stops arriving
Klaviyo
Klaviyo watches your sending closely because ecommerce marketing is where complaint problems live, and it will restrict an account that misbehaves. The support relationship is oriented toward merchants and the guidance tends to be practical: prune the list, segment on engagement, stop mailing people who have ignored you for a year.
SendGrid
Support latency and abrupt suspension are the two themes that dominate SendGrid's public reviews, consistently enough to be a planning input rather than a rumour. A campaign that spikes volume against a shared pool is exactly the pattern a large platform acts on first. Keep a fallback path warm and know how you would reach a human before you need to.
Getting people onto the list in the first place
Klaviyo
Sign-up forms, pop-ups and their targeting rules are part of the product, and the collected data lands directly in the profile with no glue in between. That is a genuine time saving for a store and it is also another thread tying you to the platform.
SendGrid
There is no meaningful form product; you build the capture yourself or buy it elsewhere and push contacts in through the API. That is fine for a team that already has its own signup flow and an unwelcome extra project for a small store that assumed it was included.
Pros and cons, side by side
Klaviyo
Strengths
- A profile assembled from live store activity, so a segment that describes behaviour is a few clicks rather than a data pipeline that somebody has to keep running afterwards.
- Revenue attribution is the product rather than a report, which gives a store owner the number that justifies the subscription without exporting anything into a spreadsheet first.
- Flows branch on store events, with abandoned-cart and back-in-stock sequences already built, and a merchant can assemble a working one in an afternoon without engineering help.
- Sign-up forms and their targeting rules are part of the product, and whatever they collect lands directly in the profile with no glue in between for anyone to maintain.
Trade-offs
- The meter counts active profiles, so signups you never message raise the invoice, and the plan steps up automatically as profiles accumulate while never stepping back down on its own.
- Sending is capped at a multiple of the profile count, and that cap is a hard stop in the middle of a campaign rather than an overage line on a later invoice.
- The transactional story is thin, so order confirmations come from the store platform or another vendor — making this an addition to the stack rather than a consolidation of it.
- One account per store, so an agency administers a collection of separate accounts rather than tenants inside one, with no view across the portfolio.
SendGrid
Strengths
- Transactional and marketing mail under one account and one vendor relationship, which turns receipts, password resets and campaigns into a single procurement conversation.
- Subusers give per-tenant credentials, reputation, suppression and reporting, which is frequently decisive for anybody sending on behalf of clients rather than only for themselves.
- A dormant contact costs nothing until you mail it, which is the better economic shape for a business sitting on a large and mostly quiet list.
- An API and an import rather than a native sync, which a team with its own warehouse often prefers because the definition of a customer stays theirs rather than the vendor's.
Trade-offs
- Contacts carry custom fields you populate yourself, so every behavioural attribute in an email exists because somebody built a pipeline and is still maintaining it this quarter.
- You get opens, clicks and deliveries, and joining those to money is your own work — which most teams never do, and therefore cannot say what the channel is actually worth.
- Automations are list-and-trigger shaped rather than behaviour shaped, so reacting to something that happened ten minutes ago requires the pipeline nobody built.
- There is no meaningful form product, so list growth becomes a project that a small store had reasonably assumed was included in the price.
Pick in thirty seconds
Choose Klaviyo if
- You run an online store and want email that reacts to browsing, carts and order history without building the pipeline yourself.
- Revenue per campaign is the number you need to justify the spend, and you want it calculated for you.
- A merchant rather than an engineer will own the flows day to day.
- Sign-up forms and list growth being part of the same product is worth real money to you.
Choose SendGrid if
- Transactional and marketing mail on one vendor relationship is a genuine requirement rather than a preference.
- Your segmentation is list-shaped, so a behavioural profile would be capability you pay for and never use.
- You send on behalf of customers and need per-tenant credentials, suppression and reporting.
- You have a data warehouse and would rather own the attribution join than accept a vendor's default windows.
What actually moves when you switch
In roughly the order you would do it. The expensive parts of an email migration are never the send call.
- Establish first whether this is a replacement or a split, because most stores end up with a split. Transactional mail usually stays where it is and only the campaign side moves, which means adding a vendor rather than swapping one — and the plan should say so before anybody exports a contact list.
- Export contacts with their consent timestamps rather than only their addresses. When somebody opted in, and to what, is the one record that cannot be reconstructed afterwards and the one a regulator asks for. Custom fields come out cleanly; the provenance behind them generally does not.
- Reconcile the suppression lists and name the system that is authoritative about consent. The failure here is specific and public: somebody unsubscribes from marketing in one tool and stops receiving order confirmations from the other, which is a support problem and possibly a compliance one.
- Connect the store integration and let it backfill before writing a single segment. Profiles are assembled from order and browse history, so a segment authored on day one evaluates against a fraction of the data it will hold on day thirty, and the figures you show a stakeholder will be wrong in an embarrassing direction.
- Rebuild the automations rather than porting them. A list-and-trigger automation and an event-driven flow are different models rather than different syntaxes, so every sequence is a design decision again — which is the point of moving, but it is design work with a calendar rather than an export.
- Split the subdomains before the first send. If campaigns are leaving the account that also sends receipts, give each its own subdomain and DKIM keys so a campaign's complaint rate cannot reach the transactional standing. This is the cheapest protective step in the whole migration and the one most often skipped.
- Prune before importing, because on the profile-metered side the list is the invoice. Every address that has ignored you for a year costs money the moment it arrives and drags the engagement metrics down with it, and pruning afterwards leaves you on a tier the plan will not step back down from by itself.
- Accept that the attribution history stays behind. Revenue per campaign does not export into any form another tool can use, so year-on-year comparisons break at the migration date. Snapshot the reports somebody will want to cite before the account closes, and warn them the series has a seam in it.
Questions to ask before you sign
Put these to a sales rep, or find the answer in the documentation before anyone quotes you a number.
- How many of our best-performing messages actually react to behaviour, and how many are announcements sent to a list on a schedule?
- What is our active profile count today, and what does it become in twelve months if nobody makes pruning somebody's job?
- Who owns email day to day — a merchant or an engineer — and which of these two tools matches how that person works?
- Once marketing and transactional live in different systems, which one holds the authoritative record of consent, and who wrote that down?
- Do we have a warehouse and somebody who would maintain an attribution join, or would we be accepting a vendor's default windows and calling it measurement?
- Do we send on behalf of other businesses, and does the option we are leaning toward give each of them isolated credentials, suppression and reporting?
- If we mail a small list frequently, has anybody checked the send cap against our real cadence rather than against our monthly total?
Common questions
Is SendGrid's marketing product good enough to replace Klaviyo?
For a business whose email is announcements and newsletters, comfortably yes, and the saving is large. For a store whose best-performing messages are abandoned cart, browse abandonment and post-purchase sequences, no — not because the sending is worse but because the data is not there. You can build the equivalent by piping store events into contact fields and triggering on them, and the honest estimate for that is weeks of engineering plus ongoing maintenance, which is frequently more expensive than the subscription it avoids.
Why does my Klaviyo bill go up when I am not sending more?
Because the meter is profiles rather than sends, and profiles accumulate on their own. Every signup, every checkout that captured an address, every import adds to a count that the plan tracks upward automatically and does not track back down. The discipline that keeps it in check is a standing suppression policy for people who have not engaged in a year, applied on a schedule. It also improves deliverability, so it is worth doing regardless of what it does to the invoice.
Can I keep transactional mail on SendGrid and run marketing on Klaviyo?
Yes, and it is the arrangement a large number of stores end up with. Use separate subdomains for the two so their reputations cannot affect each other, and decide explicitly which system holds the authoritative record of consent and unsubscribes. The failure mode to avoid is two systems each maintaining their own view of who has opted out, because the first time somebody unsubscribes from marketing and then stops receiving order confirmations, you have a support problem and possibly a compliance one.
What does the volume cap on a Klaviyo plan actually mean?
Sending is limited to a multiple of your profile count, and past that limit sends stop rather than costing extra. That is fine for a normal cadence and it bites in exactly one situation: a small, highly engaged list that you mail frequently. If you have ten thousand profiles and a daily send, run the arithmetic before you commit, because the ceiling is a hard stop in the middle of a campaign rather than an overage line on the invoice.
How hard is it to leave either one?
Contacts export cleanly from both, and that is the easy part. What does not export is the work: flows and automations have to be rebuilt by hand, templates cross no paradigm boundary, and attribution history stays behind entirely, so your year-on-year comparisons break at the migration date. On the Klaviyo side there is an extra thread — the native store integration means the platform holds catalogue and order data that has to be re-established elsewhere. Export a full contact snapshot with consent timestamps before you start, because proving when somebody opted in is the one record you cannot reconstruct.
Should marketing and transactional mail share a sending domain?
No, and this is the one piece of advice on this page that applies whichever vendor you choose. Campaign mail attracts complaints — that is the nature of it, even when everything is done correctly — and a complaint rate earned by a promotion should not be allowed to decide whether a password reset reaches the inbox. Give each traffic type its own subdomain with its own DKIM keys, so the two reputations are separate records as far as the mailbox providers are concerned. It costs one DNS change and it is the cheapest insurance in email.
How long does the store backfill take before segments are useful?
Long enough that the first week's numbers should not leave the room. A native commerce integration syncs historical orders and customers on connection and then builds browse and cart behaviour forward from the moment it is live, so anything describing recent activity is evaluating against a window that is still filling. A segment written on day one and shown to a stakeholder on day three will understate reality and nobody will remember why later. Give it a few weeks of live traffic before anyone treats a flow's performance as a signal.
Can SendGrid subusers work for a multi-store operation?
Yes, and it is one of the few places SendGrid is structurally ahead in this pair. Each subuser carries its own credentials, its own sending reputation, its own suppression list and its own reporting beneath a parent account somebody administers, which is exactly what an operator of several storefronts or an agency needs. The counterpart is one account per store with no consolidated view, so if portfolio-level administration matters, this dimension may outweigh everything the behavioural data model offers.
Does Klaviyo send order confirmations?
It can send transactional-style messages, and in practice most stores do not use it that way. Order confirmations and shipping notices generally come from the commerce platform itself or from a dedicated sending vendor, because those messages are triggered by systems that already own the order record and because keeping them off the marketing reputation is good hygiene. Treating a marketing platform as your receipts provider also means the mail you least want to lose depends on a subscription priced by profile count, which is a coupling worth avoiding.