Operating expenses, often called OPEX, are the costs of running your business that are not tied to producing a single unit. Rent, salaries, software subscriptions, insurance and marketing all belong here. They stay roughly the same whether you sell 100 units or 500 units in a month.
OPEX is the base cost of keeping the doors open. It also sets your break-even point, because gross profit has to cover it before you earn anything.
Worked example. A three-person agency pays 1,800 euros rent, 14,500 euros in salaries including employer contributions, 600 euros for software, 400 euros for accounting and 2,700 euros for marketing. Monthly OPEX is 20,000 euros. With a gross margin of 55 percent, the agency has to invoice 36,364 euros per month just to cover it.
Founders underestimate OPEX in two ways. The first is forgetting employer costs. A gross salary of 3,500 euros costs the company roughly 4,400 euros per month in many European countries once social contributions are added. Budget the full employer cost, not the gross salary. The second is the long tail of small subscriptions. Ten tools at 30 to 90 euros each add up to several hundred euros a month and rarely appear in a first draft.
The other frequent error is calling every operating expense fixed. OPEX is fixed in the short term, not forever. You can cancel software, cut ad spend or renegotiate rent. Split your OPEX into two columns: what you must pay next month even at zero revenue, and what you could stop within 30 days. The first column is the number that defines how much runway you really need.
In the financial plan Foundor generates, operating expenses form their own block, kept separate from cost of goods sold.
