Examples you can copy-paste into your planning doc

Numbers feel abstract until you see them move. Here are three common scenarios. The point isn’t to be “right” down to the decimal — it’s to make the hidden math obvious so you can talk about it with your team.

You have 50 people, expect 3% monthly attrition, and want 5% monthly growth. If you naïvely think “5% growth means 2–3 hires,” you’ll miss the replacement tax. In month 1, attrition removes about 1.5 people (50 × 3%). To still grow by 5% (target 52.5), you need hires for replacement and net growth — roughly 4 hires (52.5 − 48.5). The exact number changes month to month, but the pattern is stable: attrition raises the hiring bar.

You start at 20, target end headcount 35 in 12 months, with 2% attrition. Your recruiting capacity is 1 hire/month. The calculator will show you that you fall behind early. The “miss” doesn’t reset next month — it compounds, because you’re starting each month from a lower base than the target assumed. In practice, the fix is usually one of: increase recruiting capacity temporarily, reduce attrition, or adjust the timeline.

Suppose your recruiting machine improves over time: better sourcing, stronger brand, more referrals, and a tighter interview loop. Set capacity to 2 hires/month and choose Ramp up linearly. Now the model can reflect “we hire 1 early, then 2–3 later.” This is often a more realistic plan than a flat assumption, especially for startups building a recruiting function.

Want to make this viral inside your company? Share a screenshot of the forecast table and ask: “Which lever would you rather pull — reduce attrition by 1 point, or increase hiring capacity by 1 hire/month?” That single question usually triggers a productive conversation between founders, finance, and people ops.

Frequently Asked Questions

• Is monthly attrition the same as annual attrition?

  Not exactly. A monthly attrition rate compounds. For example, 3% monthly attrition is roughly 1 − (0.97^12) ≈ 30% annualized. Use a monthly rate that matches how your team usually thinks and reports.

• Does this include ramp time and productivity?

  This forecast models headcount (people), not fully productive capacity. If roles take 2–3 months to ramp, treat your hiring capacity as “fully ramped” hires, or layer a productivity model on top for workforce capacity planning.

• What if my hiring is lumpy (one big month, then none)?

  Use the ramp selector to approximate the shape, or interpret the table as an average plan. For a lumpy plan, set your capacity to the average and sanity check the peaks separately.

• How should I choose fully loaded cost?

  Fully loaded monthly cost often includes salary, payroll taxes, benefits, equipment, and a share of overhead. If you only have annual fully loaded cost, divide by 12 and enter the number in thousands (k).

• What’s a “good” feasibility score?

  If you’re using this for planning, aim for 85–100%. Scores below that usually mean your target depends on perfect execution, and you may want buffer capacity or a staged plan.

• How do I reduce attrition in the model?

  Treat attrition as a leadership metric. Common levers include manager quality, role clarity, compensation alignment, workload and burnout fixes, and internal mobility. In planning, even a 1% drop in monthly attrition can materially reduce hires needed.

Headcount forecasting: the “small math” that drives big outcomes

Headcount is one of the few business numbers that behaves like a flywheel. When you’re growing, every month starts from last month’s team size — and both growth and attrition compound. That compounding is why two plans that look “close enough” on a whiteboard can end up wildly different by quarter three.

This calculator is built around a very old idea: treat your team like a system with flows in and out. People join (hires), people leave (attrition), and the resulting headcount becomes the starting point for the next month. The model is intentionally simplified because the goal is not to perfectly predict; the goal is to surface constraints. Once the constraint is visible, leadership can decide whether to change the plan or invest in removing the bottleneck.

Attrition is sneaky because it’s “invisible work.” Replacing departures doesn’t feel like progress, but it consumes recruiting bandwidth. If you have 100 people and 3% monthly attrition, you lose ~3 people in an average month. If your hiring engine can produce 4 hires/month, only 1 of those hires is net growth. That means your headline plan (“we can hire 4/month!”) can translate to “we grow by 1/month,” which is a very different trajectory.

The calculator makes this explicit by computing hires needed each month as the gap between (a) your target headcount and (b) your post‑attrition headcount. It’s basically saying: “First, refill the bucket — then pour extra water to grow the level.”

Different teams plan growth differently. Some are comfortable with monthly percent growth (common in startups), others think in annual targets (common in budgeting cycles), and others set a concrete end goal (“we need 35 people by December”). The calculator supports all three, but under the hood we translate the goal into a monthly growth curve. That gives a month-by-month target headcount to compare against.

• Monthly % growth is straightforward. If you set 6% monthly growth, the target increases every month.
• Annual % growth is converted to a monthly equivalent so the table still works month-by-month.
• End goal computes the implied monthly growth needed to reach your final number over N months.

A practical planning mistake is confusing hiring activity with hiring throughput. Capacity in this calculator should represent the number of hires you can realistically close and onboard per month given your current recruiting system. If you routinely extend 6 offers to land 3 hires, capacity is 3, not 6. If new hires take 2 months to ramp before they’re fully effective, consider lowering capacity or using this plan only for headcount, then layering a productivity plan on top.

Forecasting becomes powerful when you run it like a decision game: try a “base case,” then a “best case” and “worst case.” For example: (1) current attrition, current capacity, (2) improved attrition by 1%, and (3) increased capacity by 1 hire/month. Save each scenario and compare end headcount and total cost. That comparison often reveals that investing in retention can be cheaper (and faster) than buying growth purely through more hiring.

In the forecast table, red rows indicate months where your required hires exceed capacity. Those are the months where your plan breaks first. The fix is always one of the levers: raise capacity, reduce attrition, or lower/shift the target. If the break happens early (month 1–3), your plan is aggressively constrained and will likely require immediate action. If it happens late (month 10–12), you may be able to stage investments or revisit targets mid‑year.

• Role mix: hiring 5 senior engineers is not the same as hiring 5 SDRs. Use separate forecasts by function if needed.
• Seasonality: hiring slows during holidays and spikes after budgeting cycles. Model that by lowering capacity in those months.
• Hiring lead time: pipeline built today converts to hires next month. If you’re already behind, you need to start earlier.
• Budget: headcount plans fail when finance discovers the true fully loaded cost too late. Use the cost slider early.

Bottom line: this calculator is a fast way to answer, “Is our headcount plan internally consistent?” If it says you’re at risk, that doesn’t mean you fail — it means you have a choice to make.

Cheat sheet (copy this)

Use these snippets in your docs or spreadsheets:

• Monthly attrition count: departuresₜ = headcountₜ × a
• Post‑attrition headcount: remainingₜ = headcountₜ − departuresₜ
• Target headcount: targetₜ = H₀ × (1 + g)^(t)
• Hires needed: neededₜ = max(0, targetₜ − remainingₜ)
• Hires planned: plannedₜ = min(neededₜ, capacityₜ)
• Next headcount: headcountₜ₊₁ = remainingₜ + plannedₜ

If you only know annual attrition A, a rough monthly approximation is a ≈ 1 − (1 − A)^(1/12). Use a monthly rate that matches your reporting.

A viral prompt for your team

Post your forecast table in Slack and ask: “Should we hire faster, or fix attrition?” People ops, finance, and engineering leaders usually have different instincts — and this tool makes the trade-off concrete.

• Try two scenarios: current attrition vs improved attrition.
• Try two capacities: current recruiting vs “what if we add a recruiter?”.
• Save both scenarios and compare the total cost line.