What's the difference between fixed and variable costs?

Fixed costs (rent, subscriptions) stay the same regardless of sales. Variable costs (materials, shipping, platform fees) rise with each sale.

How is contribution margin different from profit margin?

Contribution margin is per unit — selling price minus variable cost. Profit margin is overall — net profit divided by revenue across the whole business.

How does a price change affect break-even?

Strongly. A higher price widens contribution margin and lowers the units needed; a lower price does the opposite. Small price changes often swing break-even by 20–40%.

Should I include my own labor in variable cost?

Yes if you want a realistic margin. Leaving labor at $0 makes products look more profitable than they are and traps you working for free.

Break-Even Analysis Explained

Your break-even point tells you exactly how much you need to sell to stop losing money. Most small sellers never calculate it — and discover, during a slow month, that they were below break-even the whole time. This guide explains the method from the ground up.

What break-even means

The break-even point is the sales level where total revenue exactly equals total costs — neither profit nor loss. Expressed in units ("sell 120 candles/month") or in revenue ("$2,880/month"). It turns vague hope into a concrete monthly target.

Why it matters

Sets a clear goal, validates or kills a business idea before you invest, exposes pricing problems instantly, frames every cost decision (a $39/month tool requires X extra sales), protects cash flow, and is the foundation of profit planning.

Fixed costs

Costs that don't change with sales volume: platform subscriptions, software, rent, amortized equipment, insurance, and one-time upfront costs (cover design for a KDP book) you must recover. Time-based, not sale-based. Total them honestly — missing a recurring expense makes break-even look lower than it really is.

Variable costs

Costs that rise with every sale: COGS/materials, shipping and packaging, platform transaction and payment fees (Etsy ~9.5% + $0.45; eBay ~13.6% + $0.40; Shopify ~2.9% + $0.30), per-unit labor, per-sale ad spend. Sale-based, not time-based.

Contribution margin

Contribution Margin per Unit = Selling Price − Variable Cost per Unit. It's what each sale contributes toward fixed costs (and then profit). Contribution Margin Ratio = CM per unit ÷ Selling Price.

The break-even formulas

Break-Even Units = Fixed Costs ÷ Contribution Margin per Unit.

Break-Even Revenue = Fixed Costs ÷ Contribution Margin Ratio.

Units for Target Profit = (Fixed Costs + Target Profit) ÷ Contribution Margin per Unit. Always round units up.

How pricing changes break-even

A small price increase widens contribution margin and drops the units required to break even — often by a lot. Cutting price to "compete" raises break-even and traps you into needing more volume just to stand still. Model the impact before changing price.

Worked examples

Etsy candle at $24, $50 fixed, $14.73 variable → CM $9.27 → break-even ≈ 6 candles/month (~$130).

eBay store $28/month + variable fees → break-even in low double-digit units.

KDP book one-time costs $300, royalty $2.85 → 105 copies to break even.

Shopify with ad budget: $369 fixed, $45 product, $22.61 variable → 17 units/month (~$765).

Common mistakes

Forgetting a recurring expense, mixing fixed and variable costs, leaving your own labor at $0, treating one-time costs as monthly, rounding break-even down, and never recalculating after a cost changes.

Frequently asked questions

What's the difference between fixed and variable costs?: Fixed costs (rent, subscriptions) stay the same regardless of sales. Variable costs (materials, shipping, platform fees) rise with each sale.
How is contribution margin different from profit margin?: Contribution margin is per unit — selling price minus variable cost. Profit margin is overall — net profit divided by revenue across the whole business.
How does a price change affect break-even?: Strongly. A higher price widens contribution margin and lowers the units needed; a lower price does the opposite. Small price changes often swing break-even by 20–40%.
Should I include my own labor in variable cost?: Yes if you want a realistic margin. Leaving labor at $0 makes products look more profitable than they are and traps you working for free.

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