Every November I get the same call. A founder or a VP of Sales has a number for next year, usually handed down by the board, and they want to know one thing: how many account executives do I need to hire to make it. Then they tell me the answer they already worked out, which is almost always the target divided by a quota. Two million in net new, four hundred thousand per rep, so five reps. Done.
That math is wrong, and it is wrong in a way that costs real money. Not because the arithmetic is off, but because it assumes every rep you hire is fully productive on day one, hits their quota, and never quits. None of those things are true. A capacity plan built on that assumption misses the number by 30% or more, and the gap does not show up until Q3 when it is too late to fix.
I have built these models for B2B companies for over a decade, and the good news is the real version is not much harder. It is the same sheet with four honest inputs instead of one optimistic one. Let me walk through it.
Average share of B2B sales reps who hit full quota, per the RepVue Cloud Sales Index. In software specifically it is closer to 41%. If your model assumes 100% attainment, you have already lost a third of your plan.
Why most capacity plans are built backwards
The target-divided-by-quota method feels rigorous because it produces a clean number. It is the kind of math a board likes on a slide. The problem is that it treats a sales team like a row of identical machines that all run at full speed the moment you flip them on.
Here is what actually happens. You hire a rep in February. They spend their first three to seven months learning the product, building a pipeline from zero, and losing the deals every new rep loses. By the time they are at full speed, it is September. Meanwhile one of your existing reps took another job in April, so for two quarters you were down a person while you recruited and ramped a replacement. And of the reps who were fully productive all year, fewer than half actually hit their full quota.
Stack those three facts together and the five-rep plan that was supposed to deliver two million delivers maybe 1.3 million. The founder is now staring at a 700K hole and a board that remembers the slide.
The fix is not to hire more reps blindly. The fix is to model the team the way it really behaves, then hire against that.
What sales capacity planning actually is
Sales capacity planning is the process of working out how much your sales team can realistically sell in a period, then comparing that to your target so you know whether to hire, when to hire, and how many. That is the whole job.
It runs in two directions, and you need both. Top-down starts with the revenue target and works back to the headcount required. Bottom-up starts with the reps you have, applies their real productivity, and tells you what they can deliver. When the two numbers disagree, and they always do, the gap is your hiring plan. The size of the gap tells you how many people to add. The shape of it across the year tells you when.
The reason this matters more than it used to: hiring an AE is slow and expensive. Recruiting takes two to three months, ramp takes another six, and a fully loaded AE costs north of 200K a year once you count base, commission, tools, and management. Get the number wrong on the high side and you are burning cash on reps with no pipeline. Get it wrong on the low side and you miss the year. Capacity planning is how you stop guessing.
The four numbers that decide everything
Forget the single quota number. A real model has four inputs, and each one pulls your effective capacity down from the fantasy figure toward reality.
Productive selling time, not headcount
A rep on your payroll is not a rep selling. Forrester's activity study found the average rep spends about 30% of the week actually selling. The rest goes to admin, internal meetings, CRM updates, and research. You cannot plan capacity on heads in seats. You plan it on selling hours, which is one reason cleaning up the non-selling time pays for itself. I wrote about which parts of that to automate in the sales process automation guide.
Ramp time
This is the input people skip, and it is the most damaging one to skip. A new AE in B2B SaaS takes six to twelve months to reach full productivity, with seven months a fair average for a mid-market motion. During that ramp they carry a quota but cannot deliver against it. The standard fix is a ramp factor: a rep in month two might count as 0.2 of a productive rep, month five as 0.6, fully ramped as 1.0. If you hire ten AEs in Q2, plan for roughly half of their annual capacity, not all of it. I go deeper on shortening this in the piece on sales rep ramp time.
Quota attainment, not quota
Quota is what you assign. Attainment is what gets delivered. The average across B2B sits around 43%, and even healthy teams land in the 60 to 75% range for the share of reps at quota. The honest move is to model expected attainment, not assigned quota. If your historical attainment is 70% of quota per ramped rep, that is the number that goes in the sheet. Assigning a 500K quota does not put 500K in the bank.
Attrition
Reps leave. Enterprise sales teams run 10 to 20% annual attrition between voluntary exits, performance terminations, and internal moves. Every departure starts a clock: time to backfill, time to ramp the backfill, pipeline lost in the gap. Even with headcount flat on paper, attrition quietly removes 10 to 15% of your productive capacity over a year. Model it, or it models you.
Plan capacity on what reps deliver, not on what you put on their org chart.
Effective capacity is total reps multiplied by how ramped they are, multiplied by expected attainment, multiplied by one minus your turnover rate. Each of those four is below 100%. Skip any one and your plan inflates.
The model, built in one sheet
You do not need a planning tool to do this. A spreadsheet works for any team under a few hundred reps. Here is the structure I build for clients, month by month across the planning year.
The formula at the heart of it is plain:
Effective capacity = total reps × ramped percentage × expected attainment × (1 − turnover rate)
For each month, you list the reps you expect to have, mark how far each is through ramp, apply your historical attainment, and shave off the attrition you expect. Sum the months and you have what the current team plus your planned hires can really deliver. Compare that to the target. The difference is the gap you are hiring to close.
Worked example: a Series B team planning next year
Let me make it concrete with a company I will keep anonymous. Series B, selling mid-market software, target of 4M in net new ARR for the year. They had six AEs and were about to hire "four more to be safe," which they got to by dividing 4M by a 400K quota and rounding up.
We rebuilt it. Each AE carried a 400K quota but historical attainment was 68%, so a fully ramped rep delivered about 272K, not 400K. Of the six current reps, two were still ramping into Q1 and counted as roughly half. They expected to lose one rep during the year, a fair call at 15% attrition on six heads.
Run the honest baseline and the existing team was on track for about 1.5M, not the 2.4M the quota math implied. The gap to 4M was 2.5M. At 272K per fully ramped rep, that is roughly nine ramped-rep-years of capacity to find. New hires landing in Q1 deliver most of a year. New hires landing in Q3 deliver almost nothing this year because they are still ramping. The plan that actually closed the gap was seven hires front-loaded into Q1 and early Q2, not four spread evenly. Four would have missed by well over a million.
That is the whole point of the exercise. The naive method told them to hire too few, too late. The real model told them the truth while they could still act on it. If you want to pressure-test the demand side that has to feed those reps, the demand generation strategy piece covers how to size pipeline to capacity.
When to hire so reps are productive when you need them
Timing is where capacity plans live or die, because ramp lag is unforgiving. If you need a rep producing in Q3, and ramp is six months, that person has to be sitting at a desk in Q1. Recruiting takes another two to three months on top. So a rep you want productive in July, you start sourcing for in January at the latest.
This is the most common miss I see. A team realizes in May that they are behind, panics, and hires in June. Those reps do nothing for the current year except cost money, because they will not be ramped before December. The hire was correct, the timing made it useless. Front-load your hiring into the back half of the prior year and the first quarter of the plan year. Capacity you add in the second half mostly pays off next year, not this one.
There is a cash side to this too. Hiring seven reps in Q1 is a real burn before any of them produces. That tradeoff between hitting the number and managing runway is a board conversation, and a capacity model is the artifact that makes it an honest one instead of a guess. It also feeds directly into how you set quotas and design comp, which I cover in the sales compensation guide.
The mistakes I see every planning season
A few patterns show up again and again, and all of them inflate the plan.
Building the model on assigned quota instead of historical attainment is the big one. It is the difference between what you hope and what you get, and it usually accounts for the first 30% of the gap.
Ignoring ramp on new hires comes second. Teams count a Q3 hire as a full producer for the year. They are not. They are a 0.3 producer at best, and a cost center for two quarters.
Forgetting attrition entirely is third. Plans assume the team you draw in January is the team you have in December. You will lose at least one rep on a team of seven, probably more, and each one drags capacity for a quarter or two.
The last one is planning capacity without checking pipeline. You can have all the reps you need and still miss if marketing and outbound are not producing enough qualified opportunities to feed them. Capacity and pipeline coverage are two halves of the same question. I broke down the coverage side in the pipeline coverage ratio piece, and forecasting accuracy in the sales forecasting one. A capacity model that ignores either is a wish, not a plan.
Not sure your number is real?
We build the honest capacity model in a week: real attainment, ramp, attrition, and a hire-by-date plan you can take to the board. Book a free 30-minute audit and we will show you where your current plan breaks.
Book an audit →The tools matter less than the discipline here, but for what it is worth I build most of these in a HubSpot or Attio report for the live attainment data, dropped into a plain Google Sheet for the modeling, with n8n pushing weekly actuals in so the plan stays current instead of going stale in January. The setup is the same one we use across our CRM and RevOps and go-to-market work.
Frequently asked questions
How many AEs do I need to hit my revenue target?
Take your target, divide by expected attainment per fully ramped rep, not assigned quota, then add capacity to cover ramp time on new hires and expected attrition. For most B2B SaaS teams this means hiring 20 to 40% more capacity than the naive target-divided-by-quota figure suggests, and front-loading those hires early in the year.
What is a good sales capacity coverage ratio?
Plan for roughly 1.15x to 1.3x of your target in modeled capacity. That 15 to 30% buffer absorbs the reps who underperform, the hire who starts late, and the rep who quits in Q2. Planning to exactly 1.0x means any single thing going wrong puts you under, and something always goes wrong.
How long does it take a new AE to ramp?
In B2B SaaS, six to twelve months to full productivity, with about seven months a fair average for a mid-market motion. Enterprise deals with longer cycles ramp slower. Shorter, simpler sales cycles ramp faster. The number matters because it sets how far ahead you have to hire.
Should I use a spreadsheet or a planning tool?
For teams under a few hundred reps, a well-built spreadsheet is plenty. Pull live attainment from your CRM, model ramp and attrition by month, and refresh it quarterly. Dedicated planning tools earn their keep at larger scale or when finance needs scenario modeling tied to the broader plan. Most companies I work with do not need one yet.
How often should I rebuild the capacity plan?
Build it during annual planning, then refresh it every quarter against actuals. Attainment shifts, a rep leaves, a hire slips by a month, and each of those changes the gap. A plan you set in November and never touch is wrong by February. The point is to keep it live, not to make it perfect once.
The honest version is the useful one
The reason capacity planning gets done badly is that the wrong version is easier and produces a friendlier number. Target over quota gives you a small headcount and a clean slide. The honest version gives you a bigger number, an earlier hiring date, and a harder conversation about cash. But it is the one that hits the target.
If you are heading into a planning cycle and the only model you have is a division problem, that is the thing to fix first. Build the four-input version, find out what your team can really deliver, and hire against the gap with enough runway for ramp. It is a week of work that decides whether you make the year.
If you want a hand building it, that is a lot of what we do at Ziel Lab. Get in touch and we will put the real model in front of you.