E-Commerce Platform Break-Even Analysis: Month 21 Plan

Fixed costs $38.1K/mo Base monthly burn

Contribution margin 86% After variable costs

Break-even revenue $44.5K/mo Monthly target

Break-even timing Month 21 Model turns positive

Break-even calculator

Use this calculator to test whether monthly revenue can cover variable expenses and the fixed cost base.

Lean Base Full

Monthly revenue Revenue sets the margin available to cover the fixed cost base. $ Low sales High sales Variable expenses Use direct costs that rise with sales, like commissions, support, hosting, and payment fees. $ Low costs High costs

Money available to cover fixed costs $148,000 $170,000 revenue - $22,000 variable expenses

Margin ratio

87%

Covers fixed costs

Yes

Fixed monthly costs This is the monthly cost base your contribution margin has to cover. $ Light base Heavy base

Break-even chart Revenue Total costs

Which e-commerce marketplace expenses are fixed, and which move with sales?

Cost classification

Break-even gets unreliable when fixed spend is treated like usage spend, or usage spend is treated as flat. For this marketplace, watch wages at $28,750 per month in the first year, variable platform fees, and support that rises with disputes.

Expense	Cost	Break-Even Treatment	Common Mistake
Office Rent	Fixed	Use $3,000 per month from Month 1 through Month 60.	Don’t tie rent to order count.
Software Licenses	Fixed	Use $1,500 per month as recurring platform overhead.	Don’t bury software licenses in hosting.
Platform Security Audits	Fixed	Use $1,000 per month to protect marketplace trust controls.	Don’t delay trust controls after launch.
Hosting Fees	Variable	Model at 3.0% of revenue in the first year and 2.8% in the second year.	Don’t model hosting as flat forever.
Payment Processing Fees	Variable	Model at 2.5% of revenue in the first year and 2.4% in the second year.	Don’t confuse commission revenue with processor expense.
Sales & Marketing Commissions	Variable	Model at 6.0% of revenue in the first year and 5.5% in the second year.	Don’t double-count annual acquisition budgets.
Customer Support Scaling	Semi-variable	Model at 3.0% of revenue in the first year and 2.8% in the second year as tickets rise with volume.	Don’t wait until disputes pile up.
Wages	Semi-fixed	Use $28,750 per month in the first year and $57,500 per month in the second year as staffing steps up.	Don’t hire ahead of traction without runway.

How does break-even shift from a lean launch to a full-scale marketplace?

Scenario table

Break-even rises as fixed spend grows from $67,217 to $160,967 a month. The margin also improves a bit, but higher scale still needs more revenue coverage to hold the line.

Planning assumptions only. These figures show modeled break-even cases, not guaranteed results.

Scenario	Monthly Revenue	Variable Costs	Fixed Costs	CM Ratio	Operating Profit	Break-Even Signal
Lean marketplace launch	$78,600	$11,397	$67,217	85.5%	-$14	Near break-even, but launch risk stays high.
Base marketplace build	$135,000	$18,225	$116,800	86.5%	-$25	Month 21 is the tipping point, with almost no cushion.
Full-scale marketplace	$183,800	$22,811	$160,967	87.6%	$22	Small profit shows up once repeat demand covers fixed spend.

What pushes this marketplace past break-even?

Stress test

At $135,000 in monthly platform revenue, the model is only at break-even. A 10% revenue miss, a 10% jump in fixed spend, or a 3-point margin hit quickly opens a $4,900 to $27,000 monthly gap.

Stress Case	Changed Assumption	Break-Even Revenue	Revenue Gap	Risk Signal
Current plan	No change.	$135,000	$0 cushion	No cushion if volume slips.
Revenue shortfall	Revenue falls 10% to $121,500.	$135,000	$11,700 gap	Slower seller onboarding widens the monthly shortfall.
Fixed-cost pressure	Fixed spend rises 10% to $128,480.	$148,500	$13,500 gap	Higher overhead pushes break-even farther out.
Margin pressure	Variable expenses rise 3 points, cutting margin to 83.5%.	$139,900	$4,900 gap	A weaker take rate leaves less room to cover fixed costs.
Combined pressure	Revenue falls 10%, fixed spend rises 10%, and margin drops to 83.5%.	$153,900	$27,000 gap	Paid acquisition and support costs can break the plan fast.

What should you verify before committing to the marketplace build and launch spend?

Founder checklist

Before you lock in the platform build and launch budget, check that seller supply, buyer demand, fee mix, support load, and cash runway still point to break-even. If the model cannot clear the $135,000 monthly break-even threshold, slow hiring and keep spend tight.

1Seller supply$150 CAC

Use the Year 1 seller acquisition cost to confirm you can buy enough sellers without breaking the $150,000 seller budget.

2Buyer demand$20 CAC

Check that buyer acquisition stays near $20 so the $200,000 buyer budget builds real order flow, not just traffic.

3Seller mix$19/$29/$99

Verify the seller mix can carry the monthly fee tiers for small business, independent creator, and enterprise brand accounts.

4Commission stack$0.50 + 8.0%

Prove each order still earns the fixed fee plus the Year 1 variable commission, or marketplace margin will not support scale.

5Support load30% rev

Document moderation, refund, dispute, and seller-removal rules now, then keep support staffing under the point where it pushes costs past 30% of revenue and lifts burn near $38.1K a month.

6Cash gate$135K/mo

Protect cash because minimum cash falls to $83,000 in Month 21, and do not add nonessential hires until monthly revenue clears break-even.