When a client wants to fill seats at an event, the instinct is to start with the tools — send emails, run ads, post on social. The reverse-funnel approach flips this: start with the goal and work backward through the funnel to determine whether the goal is mathematically achievable with the current list and typical conversion rates.
This framework is applicable any time a client wants to fill a class, sell tickets, or drive registrations through push marketing.
Get a specific number from the client. "Fill the room" isn't enough — you need to know:
- How many attendees do they want?
- What is the room capacity? (Overselling has consequences.)
- Are there multiple sessions? (Multiply accordingly.)
For push email campaigns promoting events or training:
| Metric | Typical Range |
|---|---|
| Open Rate | 28–44% |
| Click-Through Rate (CTR) | 2–4% |
| Click-to-Open Rate (CTOR) | 5–15% |
| Conversion Rate (CR) | 1–5% |
Conversion rate here means: of everyone who receives the email, what percentage actually registers/signs up.
Required List Size = Goal ÷ Conversion Rate
Best case (5% CR): Goal × 20 = list needed
Worst case (1% CR): Goal × 100 = list needed
Example — Goal: 100 attendees across 4 classes
| Scenario | Conversion Rate | List Size Needed |
|---|---|---|
| Best case | 5% | 2,000 contacts |
| Worst case | 1% | 10,000 contacts |
Plug in the client's real list size to get a realistic signup range:
Projected Signups = List Size × Conversion Rate (1%–5%)
Example — H.S. with 1,900 contacts:
- Low end: 1,900 × 0.01 = 19 signups
- High end: 1,900 × 0.05 = 95 signups
If the goal is 100 and the list is 1,900, the goal is not achievable through email alone. This is a list-size problem, not a campaign performance problem.
Run this analysis before launching any event promotion campaign. Key trigger questions:
If you don't run the math upfront, you'll end up defending solid email metrics to a client who expected a full room.
When the math shows the goal is unreachable with the current list, present the data directly and reframe the conversation:
The goal isn't to lower expectations for its own sake — it's to redirect energy toward what will actually move the number.
If the list can't support the goal, there are three levers:
Client: [1]
Campaign: Asbestos training signups for 4 required classes (Nov–Dec)
List size: 1,900 contacts
Client goal: 100 attendees
Actual signups: 28
Email performance was within benchmark ranges (open rate 34–42%, CTR 2–3%, CTOR 5–9%). The issue was never the campaign — it was that 100 signups from a 1,900-contact list requires a 5.3% conversion rate, which is at or above the top of the realistic range.
The correct response: present the reverse-funnel math to the client, validate that 28 signups is actually within the expected range (19–95), and execute a multi-channel push to squeeze toward the upper end.