Car Modification Shop Break-Even Analysis: $43K Monthly Revenue

Fixed costs $34.7K/mo Base monthly burn

Contribution margin 81.3% After variable costs

Break-even revenue $42.7K/mo Monthly target

Break-even timing Month 1 Launch month

Break-even calculator

Use this calculator to test whether monthly shop revenue can cover direct parts, fees, and fixed overhead.

Lean Base Full

Monthly revenue Revenue sets the cash available to cover shop costs each month. $ Low sales Busy month Variable expenses These rise with each job, like parts, commissions, and processing fees. $ Lean costs Heavy costs

Money available to cover fixed costs $169,952 $203,333 revenue - $33,381 variable expenses

Margin ratio

84%

Covers fixed costs

Yes

Fixed monthly costs This is the monthly cost base the shop must cover before profit starts. $ Lower overhead Higher overhead

Break-even chart Revenue Total costs

Which shop expenses stay fixed, and which move with sales?

Cost classification

Break-even only works if each expense behaves the way the model says it does. Treat rent as monthly, parts as job-linked, and payroll as capacity that steps up when hiring changes.

Expense	Cost	Break-Even Treatment	Common Mistake
Garage Lease	Fixed	Include $6,500 every month from Month 1 through Month 60.	Spreading rent by job and hiding the monthly floor.
Lead Technician payroll	Semi-fixed	Model the $85,000 annual salary as capacity that stays flat until staffing changes.	Treating skilled labor as if it rises with every job.
Technician payroll	Semi-fixed	Step payroll up as headcount grows from 1.0 FTE in the first year to 2.0 FTE in the second year.	Missing the hiring step when job volume outgrows bay capacity.
Parts and install materials	Variable	Tie items like ECU software licenses, vinyl material, suspension parts, brake parts, and dyno consumables to each completed job.	Using one blended monthly estimate instead of job-level usage.
Sales Commissions	Variable	Apply 5.0% of revenue in the first year, falling to 3.0% by the fifth year.	Leaving commissions in fixed overhead and overstating margin.
Payment Processing Fees	Variable	Apply 2.5% of revenue in the first year, falling to 2.1% by the fifth year.	Forgetting card fees on high-ticket jobs.
Utilities Electricity	Semi-variable	Start with the $800 monthly base, then watch usage as lifts, booth work, and dyno sessions increase.	Calling all power spend fixed when equipment use drives peaks.
Insurance General Liability	Fixed	Include $450 every month as recurring operating overhead.	Moving insurance into per-job margin and understating break-even volume.

How does break-even change from a lean bay mix to a full-service car modification shop?

Scenario table

Break-even moves with bay use and service mix. Lean volume can sit close to the line, while a fuller mix of tunes, wraps, suspension, brake work, and dyno runs adds a wider cushion because revenue grows faster than fixed shop cost.

Scenario figures are planning assumptions, not guarantees, and real results will move with labor mix, bay utilization, and parts costs.

Scenario	Monthly Revenue	Variable Costs	Fixed Costs	CM Ratio	Operating Profit	Break-Even Signal
Lean shop mix	$427k	$80k	$347k	81.3%	$0k	Right on the line, so small delays can flip it to loss.
Base shop mix	$1.18M	$221k	$347k	81.3%	$615k	Strong cushion here; fixed cost is covered with room left over.
Full shop mix	$2.91M	$451k	$508k	84.5%	$1.95M	Best cushion of the three, with break-even far below revenue.

What breaks the break-even plan if bookings slow or costs creep up?

Stress test

The base plan clears break-even with a wide cushion, but that buffer shrinks fast if bookings slip, payroll and rent rise, or rework pushes variable spend higher. Watch overtime, warranty labor, parts discounts, and underused bays.

Stress Case	Changed Assumption	Break-Even Revenue	Revenue Gap	Risk Signal
Current plan	No change.	$427k	$756k cushion	Base case clears break-even with room.
Revenue shortfall	Bookings fall 25%.	$427k	$461k cushion	Still clears break-even, but the buffer shrinks.
Fixed-cost increase	Overhead and payroll rise 15%.	$491k	$692k cushion	Higher fixed load still works, but cash burn rises.
Margin pressure	Variable expenses rise to 25.0% of sales.	$463k	$721k cushion	Rework or overtime can erode margin fast.
Combined pressure	Bookings fall 25%, overhead rises 15%, and variable expenses rise to 25.0% of sales.	$491k	$397k cushion	Three hits cut the cushion sharply.

What should you verify before you lock the lease and buy the shop equipment?

Founder checklist

Before you lock the lease or buy the dyno, prove booked work can clear the fixed load. In this model, that means about $42.4K a month in sales, $34.7K a month in fixed cost, and a $1.139M cash trough in Month 2.

1Demand proof$42.4K/mo

Check that signed work can reach this monthly break-even level, or the lease and build-out will outrun demand.

2Fixed load$34.7K/mo

Keep lease, utilities, insurance, software, and base pay inside this monthly burden before you add another hire.

3Margin check82% CM

Each $1 of sales keeps about $0.82 after parts, commissions, and card fees, so protect pricing on high-parts jobs.

4Bay capacity50 jobs/mo

Hold hiring flat until bays and tech time can handle about 50 jobs a month; if bay use is weak, delay the next technician.

5Cash cushion$1.139M

Carry this minimum cash in Month 2 to absorb the $281K startup spend before throughput catches up.

6Launch timingMonth 1-7

Time the lift, dyno, alignment, and paint booth installs to booked jobs, secure wraps, kits, fluids, and consumables, and take deposits on suspension and brake work.