# Sales Headcount & Capacity Planning Calculator

> The exact formula, ramp-curve table, and worked numeric example for turning a revenue target, quota, and ramp assumptions into a defensible number of reps to hire, and when to start each req.

Free calculator/tool for sales leaders. Topic: [Sales Leadership & GTM Strategy](https://www.peerlab.ai/library/topic/sales-leadership-gtm-strategy/). Published by PeerLab in the [Sales Enablement Resource Library](https://www.peerlab.ai/library/). Source: https://www.peerlab.ai/library/sales-headcount-capacity-planning-calculator/

## How to use it

Replace every bracketed number with your own revenue target, quota, and ramp curve, replicate the worked example row-by-row in a spreadsheet (one row per rep/hire cohort), and re-run it whenever the revenue target changes.

## What's inside

- Core formula: Reps Needed = Revenue Target ÷ Effective Annual Quota per Rep
- Ramp-adjusted capacity table (month-by-month productivity %)
- Weighted annual capacity formula for mid-year new hires
- Attrition buffer formula and rule of thumb
- Fully worked numeric example with 3 different hire start dates
- Blended vs. segmented calculation guidance
- Hiring-timeline back-solve (when to open each req)
- Sensitivity-check questions to stress-test the final number

## Core Formula

**Reps Needed = Annual Revenue Target ÷ Effective Annual Quota per Rep**

where:

**Effective Annual Quota per Rep = Full Annual Quota × Weighted Ramp Factor × Expected Attainment %**

- *Weighted Ramp Factor* = 1.0 for already-ramped reps; less than 1.0 for reps hired mid-year (see ramp table below).
- *Expected Attainment %* = your realistic average attainment, not 100%, use your actual trailing 4-quarter team average.

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## Ramp-Adjusted Capacity Table (example: 4-month AE ramp)

| Month on the job | Productivity % |
|---|---|
| 1 | 0% |
| 2 | 25% |
| 3 | 50% |
| 4 | 75% |
| 5+ | 100% |

**Weighted annual capacity for a mid-year hire** = (sum of monthly productivity % for the months they're employed that calendar year) ÷ 12.

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## Worked Example

- Revenue target (net-new ARR): **$10,000,000**
- Full annual quota per fully-ramped AE: **$800,000**
- Realistic expected attainment (trailing average, not aspirational): **70%**
- Effective quota per ramped rep = $800,000 × 0.70 = **$560,000**

**Existing base:** 12 already-ramped reps × $560,000 = **$6,720,000**
**Remaining gap to close via new hires:** $10,000,000 − $6,720,000 = **$3,280,000**

Modeling 3 new-hire cohorts starting at different points in the year:

| Hire start | Months employed this year | Weighted capacity fraction | Effective quota this year |
|---|---|---|---|
| Jan 1 | 12 | (0+.25+.5+.75+1×8)/12 = 0.79 | $560,000 × 0.79 = $442,400 |
| Apr 1 | 9 | (0+.25+.5+.75+1×5)/12 = 0.54 | $560,000 × 0.54 = $302,400 |
| Jul 1 | 6 | (0+.25+.5+.75+1×2)/12 = 0.29 | $560,000 × 0.29 = $162,400 |

Two reps per cohort → total new-hire contribution this year ≈ (442,400 + 302,400 + 162,400) × 2 = **$1,814,400**: short of the $3,280,000 gap, meaning either the hiring plan needs more reps, an earlier start date, or the target needs revisiting. **This is the actual purpose of the calculator: catching gaps like this before the plan is finalized, not after Q3.**

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## Attrition Buffer

**Rule of thumb:** Additional reps to hire for attrition = (Reps Needed) × (Expected Annual Attrition %) ÷ 2

*(÷2 because departures are assumed to land, on average, mid-year: the replacement only misses roughly half a year of ramped capacity, not the full year.)*

Example: 18 reps needed, 15% expected attrition → 18 × 0.15 ÷ 2 ≈ **1.35 → hire 1-2 extra reps into the plan as attrition cover.**

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## Blended vs. Segmented Method
Use a single blended quota/attainment figure only for a rough first pass. For a real plan, run this calculation **once per segment** (SMB / Mid-Market / Enterprise): attainment rates and ramp times differ enough by segment that a blended number will misallocate hires toward whichever segment is easiest to model, not whichever segment needs the reps.

## Hiring Timeline Back-Solve
Work backward from the desired "fully ramped by" date: Start Date = Desired Ramped Date − Ramp Length (e.g., 4 months) − Average Time-to-Fill (typically 6-10 weeks for a quota-carrying role) − Notice Period Buffer (2-4 weeks).

## Sensitivity-Check Questions
- What happens to the reps-needed number if attainment comes in 10 points below your assumption?
- Does the plan assume any productivity gains (e.g., from new tooling) that haven't actually shipped yet?
- Is the ramp curve based on your own historical data, or an industry-average guess?
- If attrition doubles, does the plan still hit the target, or does it silently fail?