CAC payback months by monthly ARPU & acquisition cost
Short answer: how fast you recover acquisition spend is the ratio of your customer acquisition cost to the monthly gross profit each customer throws off. Across this 56-cell sweep at 80% gross margin, 23 of 56 ARPU/CAC combinations pay back within the healthy 12-month window and 28 blow past 18 months into danger territory. A $99/mo plan with an $1,800 CAC takes 22.7 months to break even; drop CAC to $600 on a $59/mo plan and the same product pays back in 12.7 months. The full grid is below.
CAC payback in months by ARPU and acquisition cost
Rows: monthly ARPU. Columns: customer acquisition cost. Each cell is the payback period in months. Green ≤ 6, grey 6–12, amber 12–18, red over 18.
| ARPU \ CAC | $150 | $300 | $600 | $1,000 | $1,800 | $3,000 | $5,000 | $8,000 |
|---|---|---|---|---|---|---|---|---|
| $19/mo | 9.9 | 19.7 | 39.5 | 65.8 | 118.4 | 197.4 | 328.9 | 526.3 |
| $39/mo | 4.8 | 9.6 | 19.2 | 32.1 | 57.7 | 96.2 | 160.3 | 256.4 |
| $59/mo | 3.2 | 6.4 | 12.7 | 21.2 | 38.1 | 63.6 | 105.9 | 169.5 |
| $99/mo | 1.9 | 3.8 | 7.6 | 12.6 | 22.7 | 37.9 | 63.1 | 101 |
| $149/mo | 1.3 | 2.5 | 5 | 8.4 | 15.1 | 25.2 | 41.9 | 67.1 |
| $249/mo | 0.8 | 1.5 | 3 | 5 | 9 | 15.1 | 25.1 | 40.2 |
| $399/mo | 0.5 | 0.9 | 1.9 | 3.1 | 5.6 | 9.4 | 15.7 | 25.1 |
Provenance
- Engine
- CAC Payback Calculator (
cac-payback-calculator) - Source
- Computed live from
/engines/cac-payback-calculator.js - Grid
- 7 ARPU tiers × 8 CAC levels = 56 cells
- Computed
- 2026-05-23
- Held constant
- 80% gross margin · 24-month LTV horizon (engine default)
Every value above and in the table is the deterministic return value of the shipped engine bundle, recomputed independently in continuous integration and diffed against this page on every build. The engine is pure (no clock, no randomness): the same inputs always produce the same output. No number on this page was hand-typed or estimated.
How to read this dataset
- Find your monthly ARPU on the left, your blended acquisition cost across the top, and read the payback period where they meet.
- Red cells take over 18 months to recover — the canonical danger zone for a bootstrapped founder funding growth from cash flow. Raise ARPU or cut CAC before scaling spend.
- The CSV adds monthly gross profit, 24-month LTV, the LTV:CAC ratio, and both health classifications for every cell, so you can model your own margin.
Want to run your own inputs instead of this grid? Use the CAC Payback Calculator. For the exact math, defaults, and what the model can't tell you, read the methodology page. For a worked rescue of a 19-month payback curve, see fixing a 19-month CAC payback, and for an honest acquisition-cost method, an honest CAC method for solo founders.