ConvertKit and MailerLite both market to solo operators and small teams, but they handle scale differently. If you’re choosing between them—or wondering when to migrate—the differences matter most once you cross 10,000 subscribers and again at 50,000.
This isn’t about features in general. It’s about what changes when your list grows, where each platform’s architecture shows stress, and what you pay for the privilege.
Pricing structure and list-size thresholds
ConvertKit charges based on total subscribers across all lists and segments. As of November 2026, the Creator tier starts at $29/month for up to 1,000 subscribers, then moves to $49/month at 3,000, $79/month at 9,000, and $108/month at 15,000. Past 50,000 subscribers, you’re into custom pricing (ConvertKit pricing, checked November 2026).
MailerLite uses the same subscriber-count model but undercuts ConvertKit significantly. The Growing Business plan runs $18/month for up to 1,000 subscribers, $36/month at 5,000, $60/month at 10,000, and $180/month at 50,000. Past 100,000, you request a quote (MailerLite pricing, checked November 2026).
Both platforms count all subscribers once, even if they appear in multiple segments. Unsubscribes and deleted contacts drop off the count within 24 hours on MailerLite and immediately on ConvertKit.
Segmentation speed and filter complexity
ConvertKit’s visual automation builder and tagging system handle complex logic well, but segment recalculation slows as list size grows. If you build a segment using multiple date-based conditions and tag intersections, expect refresh times between two and ten minutes on lists above 25,000 subscribers. Segments update in near-real-time for smaller lists.
MailerLite’s segmentation engine is faster at scale but less flexible. You can stack conditions—opened campaign X, clicked link Y, signed up before date Z—but advanced operators hit the 15-condition limit quickly. Recalculation on large segments takes under a minute in most cases, even above 50,000 subscribers, because MailerLite pre-indexes common filters like campaign engagement and signup date.
One non-obvious difference: ConvertKit lets you nest sequences inside automations and trigger them from segment membership. MailerLite requires you to export the segment and manually upload it to a workflow, which adds friction if you’re running multi-step nurture campaigns based on behaviour.
Delivery speed and send throttling
Neither platform publicly documents per-account send rates, but operator experience shows the gap. ConvertKit typically delivers a broadcast to 50,000 subscribers within 20 to 40 minutes. MailerLite completes the same send in 10 to 20 minutes, because it queues campaigns differently and spreads load across more outbound IP pools.
Both platforms throttle new accounts. If you migrate a large list and immediately send a broadcast, expect your first few campaigns to trickle out over 60 to 90 minutes regardless of platform. Throttling lifts after a few sends with normal engagement metrics.
ConvertKit offers domain authentication (custom DKIM and return-path) on all paid plans. MailerLite includes it only on the Growing Business tier and above, so free and low-tier accounts share domain reputation with other users—a risk if you care about inbox placement.
Who each platform suits
ConvertKit makes sense if you sell digital products directly from email, need advanced automation branching, or rely heavily on creator-focused integrations (it connects natively to more course platforms and membership tools). The higher cost buys you flexibility in workflow design and better support documentation for complex sequences.
MailerLite fits operators who prioritise cost over automation depth, send frequently to large lists, or run straightforward nurture sequences without heavy conditional logic. The interface is faster, the price scales better, and delivery speed matters if you’re running time-sensitive campaigns or coordinating sends with other channels.
Neither platform handles true transactional email well—order confirmations, password resets, account alerts. For that, you still need a dedicated service like Postmark or a developer-focused API.
Migration and export limits
Both platforms let you export your full subscriber list as CSV at any time, with no gating or delay. ConvertKit includes custom field data and tag history in the export. MailerLite includes custom fields but not granular activity logs, so if you track detailed behaviour over time, export your campaign reports separately before migrating out.
Importing into either platform is straightforward for lists under 10,000 subscribers. Above that, both require you to confirm list provenance and may ask for proof of consent if engagement looks low. Plan for a 24- to 48-hour review window on your first large import.
If you’re already on one platform and considering a switch, test segmentation and automation performance with a 5,000-subscriber sample before committing. The workflow paradigms differ enough that rebuilding sequences takes longer than migrating the list itself.
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