Most sales-capacity plans are built with a single formula: target ÷ quota. It's fast, it's clean, and it's wrong. It assumes every rep is fully ramped, hits 100% of quota, and never leaves. Real teams don't work that way — and the difference is the reason so many annual plans miss by 20–30% and blame it on macro.
This guide walks through the model that actually works: a monthly cohort capacity model that accounts for expected attainment, ramp curves, and attrition. Run the numbers alongside the sales capacity calculator as you read.
Why target ÷ quota fails
The industry data is unambiguous: only 43% of quota-carrying reps hit number in any given year, and team-wide average attainment sits at 60–75% for healthy SaaS teams. A model that assumes 100% attainment therefore under-hires by roughly the inverse of that gap — 25–40%.
Layer on ramp — the 3–12 months a new hire takes to reach full productivity — and mid-year hires only deliver a fraction of quota in their first calendar year. A rep hired in April with a 6-month ramp is productive for maybe 3 months of Q4. Target ÷ quota assumes 9 months of full contribution. The plan is broken before Q1 starts.
The productive-rep-equivalent (PRE) model
The honest capacity number is:
Required productive FTE = Target ÷ (Quota × expected attainment)
A "productive FTE" is one fully-ramped rep at your team's real attainment. If quota is $1M and attainment averages 70%, one PRE contributes $700K. To hit $10M you need roughly 14.3 PRE — not 10.
Then convert PRE to headcount by adjusting for ramp. A rep hired at the start of the year with a 6-month ramp counts as roughly 0.75 PRE that year; a rep hired mid-year counts as roughly 0.25–0.5 PRE. Sum the contributions of every existing rep and every planned hire — that's your modeled capacity.
Ramp by cohort
The mistake most models make is treating ramp as a lump sum ("6 months to productive"). The reality is a curve. A typical mid-market AE ramp looks like:
- Month 1–2: 15–25% of quota (training, first meetings)
- Month 3–4: 40–55% (early-stage pipeline building)
- Month 5–6: 70–85% (deals starting to close)
- Month 7+: 100% (fully ramped)
Integrate under that curve and the average productivity of a rep during a 6-month ramp is roughly 50%. That means your first-year cost per new hire is much closer to full salary + variable at 50% productivity, not the ramp-adjusted "0.75 rep" you'd hope for. Model both — capacity and loaded cost — before signing off.
Attainment: use the median, not the average
Average attainment on a small team is easy to distort. Two overperformers at 140% and eight reps at 50% average to a healthy-looking 68%, but the reality is that eight of ten reps are missing badly. Use the trailing four-quarter median as the input to your capacity model. It's a better predictor of whether the next hire will contribute.
Attrition: plan the backfill
Voluntary + involuntary sales attrition averages 25–35% per year in SaaS, and startups often see 40–60%. If you have 10 ramped reps and expect 25% attrition, you'll lose 2–3 reps you have to backfill just to stand still. Backfill hires are hires — put them in the plan.
Total hires needed = Growth hires + Attrition backfill
Back-solving hire dates
This is where most plans quietly fail. If a hire needs to contribute in Q3, and ramp is 6 months, they need to start in Q1. Add 8 weeks of recruiting and the requisition needs to be open in Q4 of the prior year. Work backwards from the month you need the capacity:
- Month capacity is needed
- Minus ramp length
- Minus recruiting time (typically 6–10 weeks)
- = Month the requisition opens
If your plan says "hire 12 reps in H2 to hit next year", the math rarely works — those 12 reps produce maybe 30% of their annual quota in the calendar year they were hired.
A 12-month worked example
Assume: $10M annual target, $1M quota, 70% attainment (0.7 PRE per ramped rep), 6-month ramp, 25% attrition, 8 existing ramped reps.
- Required PRE: $10M ÷ ($1M × 0.7) = 14.3 PRE
- Current PRE: 8 ramped reps × 1.0 = 8.0 PRE
- Gap: 6.3 PRE
- Effective PRE per new hire (first year, 50% ramp): 0.5
- Growth hires needed: 6.3 ÷ 0.5 = ~13 hires
- Attrition backfill: 8 × 0.25 = 2 hires
- Total plan: 15 hires, staggered Q1 → Q3
Target ÷ quota would have said "hire 2 reps" ($10M − $8M existing quota, divided by $1M). The honest number is 15. That's the size of the mistake this model catches.
Sanity checks before you present
- Is expected attainment below the trailing 3-quarter median? If not, be more conservative — most plans over-estimate attainment.
- Are you assuming ramp under 3 months? Only realistic for transactional SMB. Enterprise ramp is 9–12.
- Does the plan implicitly assume 0% attrition? Add backfill hires equal to your last 12 months of departures.
- Does the hire calendar back-solve to open requisitions before the year even starts? If yes, capacity comes late — expect a miss in H1.
When to fix productivity instead of hiring
If attainment is under 50% and pipeline coverage is above 4x, hiring more reps won't help. You have a conversion problem, not a capacity problem. Common causes: onboarding gaps, ICP drift, discovery quality, or product-market fit slippage. Fix those first — adding reps to a broken funnel just multiplies wasted spend.
The worksheet
Run the same math against your team in the Sales Capacity Calculator — plug in your existing reps, quota, attainment, ramp, and attrition, and it'll give you the PRE gap and total hires needed in seconds. Then use the Quota Attainment Calculator to inspect where the current team actually is against the plan, and the RevOps hub for the weekly-cadence templates that keep the model honest.