The sales capacity formula: a sum, not a product
The sales capacity formula estimates how much revenue a sales team can produce in a period. The basic version is reps × annual quota × average attainment %. The accurate version computes capacity month by month, adjusting each rep for ramp time and attrition.
The naive formula — and why it's wrong
capacity = reps × quota × attainment
This formula is only correct for a team that hires nobody, loses nobody, and is fully ramped on January 1 — a team that doesn't exist. It makes two systematic errors: it credits new hires with a full year of productivity they can't deliver, and it ignores that departing reps stop selling before the year ends. Both errors point the same direction: the naive formula always overstates capacity.
The ramp-adjusted formula
Compute capacity as a sum over months, not a single multiplication:
ramped_reps[m] × (quota × attainment ÷ 12)
+ Σ new_hires × ramp_curve[m - start]
- attrition_loss[m]
coverage = Σ capacity ÷ target
Each rep's contribution in a month: an existing ramped rep counts as 1.0 FTE until they leave (attrition removes rep-months pro-rata through the year); a new hire counts as their ramp-curve productivity for that month on the job — on a 5-month linear ramp: 20%, 40%, 60%, 80%, 100%.
Worked example
The canonical plan: 10 ramped reps, $1M quota, 70% attainment, 15% annual attrition, 8 hires (2 per quarter, starting in the second month of each quarter) on a 5-month ramp. Target: $10M.
| Method | Calculation | Answer |
|---|---|---|
| Naive | (10 + 8) × $1M × 70% | $12.6M — “plan covered, relax” |
| Month-by-month | Σ monthly ramped FTE × $83.3K × 70% | $8.6M — 86% coverage, -$1.4M gap |
Same team, same hires: the naive answer overstates real capacity by $4.0M — and hides that the plan is $1.4M short of its $10M target. That's the size of the error most annual plans are built on. Run your own numbers in the free capacity calculator — it does this month-by-month math live.
What one hire is worth, by start month
On a 5-month linear ramp, a new hire's in-year value as a fraction of a full rep-year:
| Start month | Productive pattern | % of a full rep-year |
|---|---|---|
| January | 5 ramp months + 7 full months | 83% |
| April | 5 ramp months + 4 full months | 58% |
| July | 5 ramp months + 1 full month | 33% |
| October | 3 ramp months, never reaches full | 10% |
In the canonical plan, hires land in the second month of each quarter — so a Q1 hire delivers ≈75% of a rep-year and a Q3 hire ≈25%. Either way the lesson holds: “we'll hire 8 reps this year” tells you almost nothing — when they start is most of the answer. More in ramp-time benchmarks and what rep attrition really costs.
FAQ
What attainment number should go in the formula?
Your trailing 12-month actual, if you have it. Industry-wide, The Bridge Group's SaaS AE research found 51% of AEs achieve quota, and RepVue's Q2 2025 Cloud Sales Index put quota attainment near 43%. Planning at 100% attainment is the single most common capacity-model error.
Does the formula change for SDRs or CS teams?
The structure is identical — substitute the team's output metric (meetings, pipeline, renewals) for quota. Ramp and attrition adjustments matter just as much.
Where can I get this as a spreadsheet?
The QuotaMath Excel capacity model ($9.99) implements this formula with monthly hiring granularity, editable ramp curves, attrition backfill, and Base/Upside/Downside scenarios.
Last updated July 2026 · Sources: The Bridge Group SaaS AE research · RepVue Cloud Sales Index