Short answer
Divide fixed costs by contribution-margin rate, then use actual seasonality to estimate the break-even date. Include every variable cost.
The answer in detail
Divide annual fixed costs by the contribution-margin rate after variable costs. The result is the sales revenue, excluding tax, at which the store covers its costs. To estimate when it reaches that point, use month-by-month seasonality rather than assuming evenly distributed sales.
The benchmark
The US Small Business Administration’s English calculator expresses break-even units as fixed costs divided by selling price less variable cost per unit. For a store-wide revenue model, the equivalent contribution-rate form is:
- Contribution after variable costs = sales excluding tax − variable costs.
- Contribution-margin rate = contribution ÷ sales excluding tax.
- Break-even revenue = fixed costs ÷ contribution-margin rate.
A simplified timing calculation is (break-even revenue ÷ forecast annual revenue) × days in the financial year. Use the actual number of calendar days in the modeled year and keep the basis consistent; the fictional example below uses 365. It assumes stable contribution rate and uniform sales over time.
Here is the source's fictional cosmetics brand:
| Annual item | Amount |
|---|---|
| Sales excluding tax | $1,500,000 |
| Cost of goods sold | $600,000 |
| Fulfillment and shipping | $150,000 |
| Payment fees | $30,000 |
| Paid acquisition | $270,000 |
| Contribution after variable costs | $450,000, or 30% |
| Fixed team, warehouse, software, and other costs | $360,000 |
Break-even revenue is $360,000 ÷ 0.30 = $1,200,000. With uniform sales, the store reaches it on day 292 of a 365-day year, around October 19 in the example. The safety margin is $300,000, or 20% of forecast sales. These are fictional USD inputs, not a currency conversion or a forecast for another store.
The rule
Include every cost that follows orders and use realized sales net of discounts and returns. Then express the result as revenue, orders, and a date.
As in the order contribution guide, acquisition can be variable if it follows sales or fixed if it is a committed annual budget. Keep the classification consistent and avoid counting it twice. In a lingerie-and-apparel field example, management's margin after manufacturing and ads omitted transaction and transportation costs. Every omitted variable cost overstated the margin rate and understated break-even revenue.
At a fictional $75 tax-exclusive AOV, each order contributes $22.50 at 30%, requiring 16,000 orders to cover $360,000. More traffic can bring the date forward without changing the revenue threshold. Raising contribution rate to 31% lowers the threshold by about $39,000. That gain could come from fewer discounts, fewer returns, or cheaper acquisition.
The steps
- Classify the P&L. Mark each prior-year line as variable or fixed. The e-commerce P&L guide provides an inventory.
- Use realized economics. Work on rolling-twelve-month revenue after discounts and returns. A Club winter-accessories brand's realized revenue was roughly 12% below displayed-price value despite limited promotions. Begin with product margin, deduct fulfillment, payments, returns, and variable acquisition, then divide fixed costs by the resulting rate.
- Date it monthly. Find the month in which cumulative sales first exceed the threshold. The approximate day is
(threshold − cumulative sales at previous month-end) ÷ current-month sales × days in that month. Use contribution itself if margins vary materially by month. - Stress-test assumptions. Examine a two-percentage-point rate decline, 10% higher fixed costs, and 15% lower sales. Link these to the site-to-P&L analysis.
| Fictional scenario | Break-even revenue | Safety margin |
|---|---|---|
| Base | $1,200,000 | $300,000, 20% |
| Contribution rate 28% | $1,285,700 | $214,300, about 14% |
| Fixed costs +10% | $1,320,000 | $180,000, 12% |
| Sales −15%, to $1,275,000 | $1,200,000 | $75,000, about 6% |
The pitfall
Uniform timing misleads seasonal stores. Allocate the fictional annual sales as 6% monthly in January–March, 7% in April–July, 8% in August–September, 10% in October, 16% in November, and 12% in December. Cumulative sales at October-end are $1.08 million. The remaining $120,000 is half November's $240,000, moving break-even to around November 15.
A team assuming October 19 might deepen early-November discounts while still covering fixed costs. Check promotion profitability. The cited winter brand makes 77% of annual sales from November to February and 3% from June to August; its calendar is evidence about that brand, not all markets. This operating threshold is also distinct from cash-flow solvency.
What to tell your team
This example is fictional:
“With $360,000 fixed costs and a 30% contribution rate, break-even is $1.2 million excluding tax, or 16,000 orders at $75. Our seasonality puts the date near November 15. A one-point contribution improvement would lower the threshold about $39,000.”
