Break-Even Analysis for Prototype Development: $109K Monthly

Fixed costs $70.3K Overhead base

Contribution margin 72% Left after variable

Break-even revenue $97.6K Monthly target

Break-even timing Month 5 Launch ramp

Break-even calculator

Test monthly revenue, variable expenses, and fixed costs against break-even for a prototype development service.

Lean Base Full

Monthly revenue Use billed project revenue before direct costs; this is the top line that funds overhead. $ Early run Mature run Variable expenses Use direct costs that rise with each project, like materials, machining, shipping, and commissions. $ Lower cost Higher cost

Money available to cover fixed costs $510,795 $677,583 revenue - $166,788 variable expenses

Margin ratio

75%

Covers fixed costs

Yes

Fixed monthly costs Use the monthly overhead the firm must cover, including salaries, facility costs, software, and insurance. $ Light overhead Heavy overhead

Break-even chart Revenue Total costs

Which prototype development expenses are fixed, and which move with sales?

Cost classification

Break-even is only reliable when monthly overhead is separated from project-driven spend. For this firm, the big swing items are materials at 12% of Year 1 revenue, outsourced services at 8%, shipping at 3%, and commissions at 5%.

Expense	Cost	Break-Even Treatment	Common Mistake
Workshop facility lease	Fixed	Use $12,500 per month as baseline overhead from Month 1 through Month 60.	Treating rent as project spend and understating the monthly sales floor.
Core engineering salaries	Fixed	Include planned full-time salaries in monthly overhead, based on active headcount in each year.	Modeling senior staff as optional labor even though they’re hired capacity.
Planned marketing budget	Fixed	Spread the first year budget of $45,000 across the year, or $3,750 per month.	Using CAC alone and forgetting the committed marketing spend.
Prototyping materials and components	Variable	Apply 12% of Year 1 revenue to the projects that consume parts and components.	Hiding material usage in overhead instead of matching it to jobs.
External lab and machining services	Variable	Apply 8% of Year 1 revenue as outsourced project delivery spend.	Burying outsourced machining in overhead instead of tying it to the project that caused it.
Direct project shipping and logistics	Variable	Apply 3% of Year 1 revenue because shipping rises with active prototype work.	Averaging freight across all months and missing heavy shipment periods.
Business development commissions	Variable	Apply 5% of Year 1 revenue when commissions are earned from closed sales.	Counting commissions as fixed payroll and overstating margin at low volume.
Added software seats, lab benches, or equipment service	Semi-fixed	Add only when project volume or staffing steps up enough to require more capacity.	Adding capacity too early and making break-even look harder than it is.

How does break-even shift across lean, base, and full prototype pipeline scenarios for this service?

Scenario table

Break-even moves fast when project volume and staffing change. Lean sits below fixed costs, base clears them by a wide margin, and the fuller pipeline adds more cushion but needs stronger utilization to hold the margin.

Planning figures use the model assumptions and are not guarantees.

Scenario	Monthly Revenue	Variable Costs	Fixed Costs	CM Ratio	Operating Profit	Break-Even Signal
Lean prototype pipeline	$888K	$249K	$786K	72%	-$147K	Below break-even, so volume is too thin.
Base prototype pipeline	$2,082K	$583K	$786K	72%	$713K	Clears break-even with a solid monthly cushion.
Full prototype pipeline	$4,539K	$1,194K	$982K	74%	$2,363K	Strong cushion, but fixed load rises too.

What breaks the break-even plan for a prototype development service?

Stress test

Delayed approvals, repeated redesigns, and higher outsourced machining quotes are the main threats. The base plan clears break-even, but the cushion drops fast if revenue slips or overhead lands before utilization does.

Stress Case	Changed Assumption	Break-Even Revenue	Revenue Gap	Risk Signal
Current plan	No change.	$1,092K	$990K cushion	Break-even is covered, but the buffer is not huge.
Revenue shortfall	Monthly revenue falls 20% to $1,666K.	$1,092K	$574K cushion	Slower starts and late approvals cut the buffer fast.
Fixed costs up	Fixed overhead rises by $10K a month.	$1,106K	$976K cushion	Premature overhead pushes the break-even line higher.
Margin pressure	Variable expenses rise from 28% to 33%.	$1,173K	$909K cushion	Rework and higher fabrication quotes eat contribution margin.
Combined pressure	Revenue drops 20%, variable expenses rise to 33%, and fixed costs reach $886K.	$1,322K	$343K cushion	Three hits leave a thin cushion and little room for slip.

Are you ready to lock the workshop lease and buildout before break-even?

Founder checklist

Don’t lock the lease or full hiring plan until you have about $109K in monthly revenue visibility. That’s roughly 10 average Year 1 projects a month at about $11.1K each, and it has to carry you through the Month 5 cash trough.

1Revenue Visibility$109K/mo

Verify signed or late-stage work near $109K a month, or about 10 average Year 1 projects, before you commit to full overhead.

2Fixed Overhead$74.9K/mo

Check the full fixed load, including the $12.5K workshop lease and the Year 1 salary stack, because that cost base hits before any variable spend.

3Contribution Margin72% CM

Hold materials, external lab work, shipping, and commissions near 28% of revenue, so contribution stays about 72% before fixed costs.

4Vendor Capacity8% outsourced

Confirm subcontracted lab and machining partners can absorb the 8% outsourced load from Month 1, so internal engineers stay on billable work.

5Launch Team5 FTE

Keep the launch team aligned to billable hours, not hope, because Year 1 runs on 5 core FTE and the Project Manager starts in Month 13.

6Cash Buffer$533K

Protect at least $533K of cash through Month 5, and delay nonessential capex from the $385K buildout if the ramp slips.