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Class Waitlist Depth Planner

Reviewed for 2026, updated September 8, 2026.

Estimates how many members you need on a class waitlist to reliably fill the late cancellations you expect, and what attendance your current waitlist would deliver, for studio and gym schedulers.

Your numbers

Results update as you type.

Your estimate

Spots expected to open per session...
Waitlist depth needed...
Spots your current waitlist would refill...
Expected attendance with current waitlist...

Estimates only. Assumptions are listed below, and you can change every input.

A waitlist only fills a canceled spot if someone on it accepts the offer in time. Some members will have made other plans, some will not see the text, and some will decline because the notice is too short. If your waitlist is three names deep and only a fraction of people accept, a busy class with two late cancels will still run with empty spots. Knowing how deep the list needs to be tells you whether to promote the class, add a section, or simply accept the gap.

This planner multiplies class capacity by your late cancellation rate to get the spots you expect to open up, then divides by your waitlist acceptance rate and a safety multiplier to find the waitlist depth that covers a typical week. It also takes the waitlist size you have now and estimates how many spots it would actually refill and what attendance the class would reach. The math is simple averaging, not a probability model, and every rate is one you enter.

How to use this tool

  1. Enter the class capacity and the share of booked spots that usually open up after the cutoff.
  2. Set the share of waitlisted members who actually accept an offer, and choose a safety multiplier for busier weeks.
  3. Add the number of members usually waiting today, then compare the waitlist depth needed against what you have and read the expected attendance.

What the math assumes

  • Spots expected to open equals capacity times your late cancel and no-show rate, treated as a plain average rather than a probability distribution.
  • Waitlist depth needed is expected open spots times the safety multiplier, divided by the acceptance rate, rounded up to a whole member; at a 0% acceptance rate no depth can cover the gap, so the planner says so instead of showing a number.
  • Each waitlisted member is assumed to accept independently at the rate you enter, and the tool does not model members who accept and then fail to show.
  • Spots refilled by your current waitlist cannot exceed the spots that opened, so a very deep waitlist stops adding attendance once the class is full again.
  • Attendance is capacity minus expected cancellations plus expected refills, expressed as a share of capacity.

Frequently asked questions

How do I find my waitlist acceptance rate?

Look at a recent month of waitlist offers and count how many were accepted before the class started, then divide by the number of offers sent. If you refill by hand, count the people who said yes when called or texted.

What safety multiplier should I use?

Use 1 if you only care about an average week. Use something around 1.5 if you want the list deep enough to cover weeks with noticeably more cancellations, such as holidays or bad weather days.

My current waitlist is deeper than needed, is that a problem?

Not for filling spots, but it is a signal. A long waitlist that rarely clears means demand exceeds supply, so consider adding a session, a bigger room, or an earlier cancellation cutoff so more spots open with notice.

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More free tools from SeatMend

  • Late Cancellation Revenue Leak Calculator: Estimates how much revenue a studio or gym loses each month and year to late cancellations and no-shows that leave spots in full classes empty.
  • Waitlist Refill ROI Calculator: Estimates the extra spots filled, extra revenue, net monthly gain and return on investment from automating waitlist refills by SMS, for studios and gyms weighing software cost against results.

Never let a canceled spot go empty

Fills studio and gym class cancellations from the waitlist by SMS.

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