How to Build a Signup Funnel in PostHog
Your signup funnel is the most important sequence of events in your product. Every percentage point of improvement at any step compounds into more activated users, more revenue, and a lower effective CAC. PostHog's funnel analysis gives you the visibility to see exactly where users drop off and the tools to understand why, without relying on a separate analytics vendor.
Most teams track signups as a single metric — total new accounts per week. That number hides the real story. Are users dropping off on the signup form, during email verification, or at the onboarding flow? This guide walks through building a multi-step signup funnel in PostHog that surfaces the specific step killing your conversion rate.
Step-by-step guide
Define your signup funnel steps and instrument events
Map the exact sequence of events a user goes through from first landing to activation. A typical SaaS signup funnel includes: landing page viewed, signup button clicked, signup form submitted, email verified, onboarding started, onboarding completed, and first core action taken. Ensure each step has a corresponding PostHog event with consistent naming like signup_form_submitted, not a mix of conventions.
- List every distinct step between landing and activation
- Verify that each step fires a PostHog event using the debugger
- Add properties like signup_method (google, email) and utm_source to each event
Create the funnel in PostHog Insights
Navigate to Insights > New Insight > Funnels in PostHog. Add each event in order as a funnel step. Set the conversion window to a timeframe that matches your expected signup flow — 24 hours for a self-serve product, 7 days if email verification is involved. PostHog will calculate the conversion rate between each step and the overall end-to-end conversion rate.
Break down by signup method and acquisition channel
Add a breakdown by the signup_method property to see if Google OAuth converts differently from email signup. Then create a second view broken down by utm_source or referral channel. These breakdowns often reveal that your overall conversion rate is dragged down by one underperforming path. If email signup has 40% higher drop-off than Google OAuth, that is a specific problem to solve.
Analyze drop-off points with session recordings
PostHog links funnel drop-offs directly to session recordings. Click on the drop-off between any two steps and PostHog shows you recordings of users who reached step N but did not reach step N+1. Watch 10-15 recordings for the highest-drop-off step to identify UX patterns — confusing form fields, slow loading, error states, or unclear calls to action. This qualitative layer turns a number into an actionable insight.
Set up funnel conversion goals and alerts
Create a PostHog Action for the final funnel step (first core action taken) and set up a webhook or Slack notification if the daily conversion rate drops below a threshold. This early warning system catches regressions from deployments or third-party changes before they accumulate significant user loss. A 5% drop in signup conversion for a week can cost hundreds of users.
Add the funnel to a shared dashboard for ongoing monitoring
Pin the funnel insight to a team dashboard alongside a trend chart showing each step's absolute volume over time. Add a funnel comparison showing this week vs. last week so changes are immediately visible. Share the dashboard with product, growth, and engineering so everyone has visibility into signup health without requesting a custom analysis.
Common mistakes
Defining the funnel with too few steps
A funnel with only signup started and signup completed tells you nothing about where the problem is. Break the flow into every distinct user action so that when conversion drops, you can pinpoint the exact step responsible instead of investigating the entire flow.
Setting the conversion window too wide
A 30-day conversion window for a signup funnel counts users who signed up weeks apart from completing onboarding, mixing very different behaviors. Match the window to your expected flow duration. If most users complete signup in one session, use a 1-hour or 24-hour window.
Not connecting drop-offs to session recordings
Numbers tell you where users drop off but not why. PostHog's strength is the direct link between funnel analytics and session recordings. If you build the funnel but never watch the recordings, you are doing half the analysis.
Tips
Use PostHog's correlation analysis on funnel drop-offs to automatically surface properties (browser, device, country) that correlate with lower conversion rates.
Create a separate funnel for each signup method (Google OAuth, email, SSO) rather than one funnel with breakdowns — the steps are often different for each method.
Add a funnel step for time-to-complete between form submission and email verification to quantify how many users are lost to email deliverability issues.
Test funnel changes with PostHog's built-in feature flags and A/B testing so you can measure the impact of UX changes directly in the funnel chart.
How Vantage helps
Vantage integrates analytics context into the product planning workflow. When you are writing a PRD for signup optimization, Vantage can pull your PostHog funnel data as context so the AI generates requirements grounded in real conversion numbers rather than assumptions.