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# Slotwise market sizing: US physical therapy clinics, 2026-2029
## Market definition
- **Problem:** appointment scheduling for PT clinics.
- **Geography and segment:** US PT clinics. Slotwise can only serve independent clinics with 10 or fewer therapists.
- **Pricing:** $3,000 per clinic per year ($250/month), the only revenue line. Billing and EHR are excluded.
## TAM
**Bottom-up (primary):** 38,000 clinics × $3,000 = **$114M per year**.
**Top-down cross-check:** The $9.8B figure covers all specialties and includes billing and EHR, so it can't be used directly. You gave no data on PT's share of it or scheduling's share of a practice-management suite, so the percentages below are my placeholder assumptions, not sourced data:
| PT share of $9.8B | Scheduling share of PT spend | Implied TAM |
|---|---|---|
| 2% ($196M) | 20% | ~$39M |
| 3% ($294M) | 30% | ~$88M |
| 4% ($392M) | 30% | ~$118M |
**Reconciliation:** The $114M bottom-up figure sits inside the plausible top-down range, but the top-down is only a loose sanity check. I'd treat **~$114M** as the TAM and trust it more because it rests on your actual clinic count and price. Note that this assumes every clinic would pay Slotwise's price. Competitors bundle scheduling into suites, so real spend on standalone scheduling may be lower.
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## SAM
- Independent clinics: 38,000 × 60% = 22,800
- Fit (10 or fewer therapists): 22,800 × 85% = **19,380 clinics**
- SAM = 19,380 × $3,000 = **$58.1M per year**, or **51% of TAM**
## SOM
This is capacity-based: 4 reps × 6 closes per month = 24 new clinics per month, or 288 per year. There is no churn, as you instructed.
| | Year 1 | Year 2 | Year 3 |
|---|---|---|---|
| Cumulative clinics (end of year) | 288 | 576 | 864 |
| Ending ARR | $0.86M | $1.73M | $2.59M |
| Recognized revenue (linear adds through the year) | ~$0.43M | ~$1.30M | ~$2.16M |
| Share of SAM (clinics) | 1.5% | 3.0% | **4.5%** |
**SOM at year 3: about 864 clinics, or $2.6M ARR, which is 4.5% of SAM and 2.3% of TAM.**
This is a ceiling for the current team, not a forecast. It assumes the reps hit 6 closes per month from day one, with no ramp time, attrition, or lead shortage. A haircut is sensible: at 70% productivity, year-3 ARR is about $1.8M (~3.1% of SAM).
## Summary
| Metric | Current (2026) | Year 3 projection |
|---|---|---|
| TAM | $114M | ~$114M (flat; see below) |
| SAM | $58.1M (19,380 clinics) | ~$58M (flat) |
| SOM | $0 (start of period) | $2.6M ARR at full productivity; ~$1.8M at 70% |
I held TAM and SAM flat because you gave no growth rates for clinic count, price, or market growth. Any growth you add would be an assumption on my part. Each 5% per year of growth in clinics or price would put year-3 TAM at ~$132M.
## Growth drivers and trends
- **Expansion:** Clinics with 11+ therapists and chains are excluded today. Adding them would raise SAM substantially. Adjacent modules (intake, reminders, billing) would increase revenue per clinic.
- **Headwinds:** Suites with scheduling bundled in (EHR and practice management vendors) may make a standalone product hard to justify. Price pressure is also possible.
- **Check:** Look at consolidation of independent clinics into chains, which would shrink SAM over time.
## Key assumptions and risks
| # | Assumption | Confidence | How to validate |
|---|---|---|---|
| 1 | 38,000 clinics and the 60% independent share are accurate | Medium-high | Check against APTA or Census/BLS data |
| 2 | 85% of independents have 10 or fewer therapists | Medium | Verify with the source of that figure |
| 3 | Every SAM clinic would pay $3,000 per year for standalone scheduling | **Low** | Customer interviews and win/loss data. Many clinics already have scheduling inside their EHR. |
| 4 | Each rep closes 6 clinics per month, sustained | Low-medium | Compare with actual trailing quota attainment and ramp time |
| 5 | Zero churn | Low | SMB software typically churns, so the 3-year numbers are overstated. Use actual retention data. |
| 6 | The top-down percentages | Low | Get a PT-specific market report |
**What would change the numbers most:** Churn would cut SOM directly. Assumption 3 is the biggest risk to TAM and SAM. A realistic penetration ceiling for a standalone scheduling tool could cut SAM by half or more. Headcount is the main lever on SOM, since more reps would raise it roughly in proportion if lead supply holds.
**Lead supply check:** 288 closes per year at a typical SMB close rate of 10-20% needs roughly 1,500-3,000 qualified opportunities per year. That is 8-15% of SAM entering the pipeline annually, so verify that your marketing can generate that volume.