The four numbers that matter
Forget elaborate maturity models. Sizing tail-spend leakage only needs four inputs: annual indirect spend, headcount, the share of indirect that lives in the tail, and what tooling you currently run.
Get those four right and you have a first estimate — enough to decide whether a deeper look is worth it.
- Annual indirect spend (AP-derived, last 12 months in USD)
- Headcount (loose proxy for transaction volume)
- % of indirect that is tail (default 31%, a model assumption; use your own number)
- Current tooling tier (email + sheets / basic P2P / unified platform)
The formula
We compare your current savings rate against a unified-platform ceiling. The model assumes 4.2% savings for email-and-spreadsheet teams, 7.3% for basic P2P and 11.4% for a unified platform (model assumptions, not customer results).
The gap, applied to your tail spend, is your annual leakage.
- tailSpend = indirectSpend × tailPct
- leakagePct = unifiedRate (11.4%) − yourCurrentRate
- annualLeakage = tailSpend × leakagePct
Try it with your own numbers
The calculator below runs the same math live. Adjust the sliders and the monthly, annual and 3-year leakage update instantly. Nothing is sent anywhere — it all runs in your browser.
If the 3-year number makes you uncomfortable, that's the point. Want a category-level view? Run the free tail spend diagnostic and unlock the full report with your work email.
