Before you start: pick a period
Break even is always per period, almost always a month. Every input must cover the same period: monthly fixed costs, per-unit costs and price. Mixing annual rent with monthly salaries is the fastest way to get a nonsense answer. Decide "per month," then convert any annual figures by dividing by twelve before you begin.
Step 1: list your monthly fixed costs
Write down every cost that does not change with how much you sell: rent, base salaries, insurance, software subscriptions, loan payments, flat-fee services. Our worked example uses $12,000 a month: $5,000 rent, $5,500 salaries, $800 insurance, $700 subscriptions and miscellaneous.
Be thorough. Pull a bank statement, not your memory. Owners consistently underestimate fixed costs by forgetting small subscriptions, annual fees that should be divided by twelve, and owner draws that are really salary. Every forgotten dollar inflates the margin of safety you think you have.
Step 2: find your variable cost per unit
Variable cost is the cost of one more unit: materials, packaging, shipping, payment-processing fees, per-unit commissions. In the example, each unit costs $15 to make and ship: $11 materials, $2 packaging, $2 shipping and processing.
Include the fees people forget. A 3% card-processing fee on a $40 sale is $1.20 per unit, and it belongs here, not nowhere. If a sales rep earns 5% commission, that is $2 per unit on a $40 price. Add waste too: if 4% of materials end up scrapped, true variable cost is 4% above the recipe.
Step 3: compute the contribution margin
Contribution margin per unit = price per unit minus variable cost per unit. The product sells at $40, so the margin is $40 minus $15 = $25 per unit. Each unit sold contributes $25 toward the $12,000 fixed-cost pile. This number is the denominator of everything that follows, so double-check it: one wrong input here corrupts the entire result.
Step 4: divide and round up
Break even units = fixed costs / contribution margin = $12,000 / $25 = 480 units exactly. When the division is not exact, always round up to the next whole unit. A result of 480.4 means 480 units still leaves you short, so the honest break even is 481. Break even revenue = 480 x $40 = $19,200.
Step 5: verify that costs equal revenue
Never trust a break even you have not verified. At 480 units: revenue = 480 x $40 = $19,200. Total costs = $12,000 fixed + (480 x $15 variable) = $12,000 + $7,200 = $19,200. Revenue equals total costs exactly, so 480 is confirmed. If the two sides do not match, an input is misclassified or mistyped; go back to steps 1 and 2 before believing step 4.
Verification also catches the most common structural error: fixed costs accidentally included in variable cost, or vice versa. If revenue overshoots costs at your computed break even, variable cost is probably overstated. If revenue undershoots, something fixed is hiding in the per-unit number.
What to do with the number
Compare 480 units against realistic sales. If you reliably sell 700 units a month, the business has room to breathe. If you sell 500, you are profitable on paper but one bad month away from a loss. If you sell 400, the model does not work at current volume, and the fix is concrete: raise the $40 price, cut the $15 variable cost, cut the $12,000 fixed base, or some combination, then recompute until break even sits comfortably below what you can actually sell.
Then convert the number into a daily or weekly target your team can act on. 480 units a month is 16 a day, or about 111 a week. A target of "16 units a day" drives behavior in a way "480 a month" never will.
The shortcut, for when you already trust your inputs
Once you have done the full exercise and trust your cost split, the whole thing collapses to one line: break even units = fixed costs / (price minus variable cost). The five steps exist to make sure the inputs in that one line are honest. Skip the verification step only when nothing has changed since the last full pass.