vs PostHog
TrailStack vs PostHog cost comparison for event analytics.
Honest cost math for teams past PostHog's free tier.
TL;DR
PostHog is a product analytics suite — autocapture and dashboards are included in the price. TrailStack ingests events into ClickHouse and exposes SQL. That costs $23 vs $324.
Check first
TrailStack won't replace PostHog if you depend on any of these:
- Autocapture — TrailStack needs you to send events explicitly via SDK or HTTP POST. Switching to explicit instrumentation takes 1-3 days for a small product
- Session replay — TrailStack stores event data, not screen recordings
- Pre-built analytics charts — you query with SQL or AI via MCP, but there are no click-to-build dashboards
- Event volume optimisation — if you can reduce volume below 1M per month by tracking only key events, PostHog's free tier may be all you need
The scenario
| Parameter | Value |
|---|---|
| Events per month | 10,000,000 |
| Average event size | 1 KB |
| Data volume per month | 10 GB |
| Retention | 12 months |
Seed-stage startup. The team started on PostHog's free tier at 1M events, autocapture is on, and volume has reached 10M per month. The first real bill is $324 per month. They need 12 months of data for product evolution tracking.
What 10M events per month costs
| Line item | PostHog | TrailStack |
|---|---|---|
| First 1M events | Free | Free |
| 1M-2M (1M events) | $0.0000500/event = $50 | — |
| 2M-10M (8M events) | $0.0000343/event = $274.40 | — |
| Storage (120 GB at 12-mo) | Included | $0.025/GB = $3 |
| Compute | Included | 1 CU = $20 |
| Total | $324.40 | $23 |
PostHog's tiered rates decrease with volume, but cost still scales with every event. TrailStack's cost is dominated by the flat compute unit. Storage at 120 GB adds just $3. That's 14x cheaper.
What happens to old data
PostHog keeps data for 7 years on paid plans (1 year on free).
TrailStack keeps all data in ClickHouse, always queryable, at $0.025 per GB per month. No time limit.
| Retention | TrailStack (1 CU) | PostHog |
|---|---|---|
| 1 month (10 GB) | $20.25 | $324.40 |
| 12 months (120 GB) | $23.00 | $324.40 |
| 36 months (360 GB) | $29.00 | $324.40 |
| 84 months (840 GB) | $41.00 | $324.40 (7-year max) |
TrailStack is 14x cheaper at any retention period. Beyond 7 years, PostHog may delete your data. TrailStack keeps it for as long as you pay for storage.
What you get for the money
PostHog at $324 per month gives you product analytics, autocapture, dashboards, and pre-built charts. Session replay, feature flags, and A/B testing are separate add-ons. Open-source and self-hostable.
TrailStack at $23 per month gives you JSON ingestion with automatic schema detection, real-time ClickHouse SQL, and wire protocol access. No dashboards or autocapture. Bring your own tools. Unlimited retention at $0.025 per GB.
The self-hosted option
You can self-host PostHog. You pay for infrastructure instead of per-event fees, but you take on ClickHouse cluster management, upgrades, and scaling. Cost-effective at high volumes if you have ops capacity.
Caveats & Sources
The 1 KB average covers autocapture events plus custom tracking. PostHog charges per event regardless of size. Event size only affects TrailStack's storage cost.
- posthog.com/pricing — usage-based, first 1M free
- posthog.com/product-analytics-explorer/pricing — tiered step-down rates
Verified against published pricing pages as of April 2026.