They bill on different units, which makes headline comparison useless. PostHog charges per event. Mixpanel and Amplitude charge per monthly tracked user (MTU). Your cost depends entirely on how many events each of your users fires.
| Free tier | ~5M events/mo (Series A) | |
|---|---|---|
| PostHog | 1M events/mo across all products | ~$1,240 events only, $1,500–2,000 with replay + flags |
| Amplitude | free under 50K MTU | Growth from ~$49, realistically $500–2,000 at this volume |
| Mixpanel | competitive base | base looks cheap — until the add-ons |
PostHog's free tier is the most generous by far: one million events a month, and that covers everything — analytics, session replay, feature flags, experiments, surveys — not just one product. It's a genuinely usable free tier for a real small product.
Mixpanel's base price looks great until you notice Group Analytics, data pipelines, feature flags and experiment reporting are all paid add-ons on the Growth plan. Amplitude is the enterprise pick — deepest analysis, best data governance — priced for teams with dedicated analysts.
The other structural point: session replay is built into PostHog and nothing else here. With Mixpanel or Amplitude you're adding [FullStory](/entry/hotjar-vs-microsoft-clarity-vs-fullstory-session-replay-and-why-clarity-is-free), [Hotjar](/entry/hotjar-vs-microsoft-clarity-vs-fullstory-session-replay-and-why-clarity-is-free) or LogRocket as a separate tool and bill.
For an engineering-led team under ~200 people, PostHog is the best value and the broadest bundle — one platform, one bill, a free tier you can actually ship on. Mixpanel suits PM-led teams that want the gentlest learning curve and don't need flags or experiments in the same tool. Amplitude is for enterprises with analysts and serious governance needs.