Plastic Injection Molding Break-Even: About $111K Monthly Sales

Fixed costs $35.0K/mo Base monthly overhead

Contribution margin 77% After variable cost

Break-even revenue $45.7K/mo Monthly sales target

Break-even timing Month 1 Launch month

Break-even calculator

Use this to test monthly revenue, direct costs, and overhead against the break-even point for a plastic injection molding shop.

Lean Base Full

Monthly revenue Revenue sets the pool that covers variable and fixed costs. $ Low sales High sales Variable expenses Direct resin, labor, and plant costs that rise with output. $ Low costs High costs

Money available to cover fixed costs $78,831 $101,888 revenue - $23,057 variable expenses

Margin ratio

77%

Covers fixed costs

$27,419 short

Fixed monthly costs Monthly overhead the margin must cover before profit starts. $ Lean shop Heavy overhead

Break-even chart Revenue Total costs

Which molding shop expenses are fixed, and which move with sales?

Cost classification

Break-even only works if each expense follows the right driver. In this model, unit-level inputs move with production, fixed overhead starts in Month 1, and staffing rises in steps as volume grows.

Expense	Cost	Break-Even Treatment	Common Mistake
Raw plastic resin	Variable	Include per unit by product, from $0.015 for bottle caps to $0.45 for electrical enclosures.	Using one blended resin rate across all parts.
Direct operator labor	Variable	Apply per unit, from $0.005 to $0.03, because it scales with units produced.	Treating labor as free once the press is running.
Spoilage/Scrap Allowance	Variable	Charge each unit for expected scrap, from $0.001 to $0.03 depending on the part.	Ignoring scrap and overstating contribution margin.
Facility Lease	Fixed	Carry $22,000 per month from Month 1 through Month 60, regardless of output in the planning range.	Spreading rent only across sold units and hiding idle capacity.
Business Insurance	Fixed	Include $3,500 per month as fixed overhead in the monthly break-even base.	Leaving insurance out because it is not tied to a job.
Energy Surcharge	Semi-variable	Model usage-linked energy as a percentage of revenue, ranging from 0.8% to 1.2% by product line.	Counting only the $4,000 base utilities line.
Mold maintenance supplies and tooling wear	Semi-variable	Scale maintenance supplies at 0.3% and precision tooling wear at 0.8% where applicable.	Treating press capacity as free after installation.
Salaried managers and added technician headcount	Semi-fixed	Add salaries in steps as full-time equivalent staffing rises, such as Mold Technicians moving from 2.0 to 6.0 FTE.	Smoothing headcount as if managers and technicians flex by unit.

How does break-even change from a lean start to full utilization in plastic injection molding?

Scenario table

Fixed costs stay high, so the lean case runs well below break-even even with a strong margin. Break-even only shows up once plant utilization lifts enough to spread overhead across more parts.

Planning cases only; actual results will move with mix, scrap, labor efficiency, and overhead absorption.

Scenario	Monthly Revenue	Variable Costs	Fixed Costs	CM Ratio	Operating Profit	Break-Even Signal
Lean run rate	$48.3k	$11.3k	$85k	76.6%	-$48k	Still far below break-even; the gap is too wide.
Base break-even	$111k	$26k	$85k	76.6%	$0	At the threshold, so any slip in output creates loss.
Full utilization	$194.9k	$42.4k	$145k	78.3%	$7.5k	Small cushion, helped by more shifts and tighter scrap control.

What breaks this molding plan below break-even?

Stress test

The plan breaks fast if resin, scrap, or downtime push margins down. A 10% revenue miss or a 5-point margin squeeze can turn a roughly $111,000 monthly break-even into an $8,500 to $22,000 loss.

Stress Case	Changed Assumption	Break-Even Revenue	Revenue Gap	Risk Signal
Current plan	No change.	$111,000	$0 gap	Tiny misses turn profit negative.
Revenue shortfall	Monthly revenue falls 10%.	$111,000	$8,500 gap	A small sales miss creates a monthly loss.
Fixed-cost rise	Fixed costs rise 10%.	$122,000	$11,000 gap	Lease, labor, or utilities can erase cushion quickly.
Margin squeeze	Contribution margin falls 5 points to 71.6%.	$119,000	$8,000 gap	Resin, scrap, or rework pressure the model fast.
Combined pressure	Revenue falls 10%, margin falls 5 points, and fixed costs rise 10%.	$131,000	$22,000 gap	Three small misses together drive a sharp loss.

Can you prove the orders, cash, and plant load before you sign the lease and buy the presses?

Founder checklist

Test the deal against break-even before you commit. If the order book, cash floor, and equipment load do not line up, the plant can look busy and still miss payback.

1Order book$111.0K/mo

Confirm signed customer orders can hold at least this monthly sales level and support the Year 1 plan of 980,000 parts across the five product families.

2Cash cushion$1.201M

Keep Month 1 cash above this floor after the $940K equipment plan, or the buildout turns into a funding gap before the line stabilizes.

3Press load$940K

Verify the facility can carry the listed machines, electrical upgrades, and air system for the 150-ton and 300-ton presses before you lock the site.

4Fixed load$85.0K/mo

Check that gross margin can cover the monthly lease, insurance, software, utilities, waste, and base wages even if output starts slow.

5Unit margin81% CM

Validate resin, scrap, labor, and packaging stay near model by part family, because a few points of margin loss can wipe out break-even.

6Staffing ramp7 FTE

Staff the general manager, sales, quality control, process engineering, mold technicians, and admin before volume ramps, and confirm packaging, cleanroom, sterilization, metrology, and service-level needs before quoting.