How many units cover your costs?
Fixed costs belong to a defined period such as a month; variable cost belongs to one unit. Contribution margin is unit price minus variable unit cost. Divide fixed costs by this margin for theoretical break-even.
Example and limitations
At fixed costs of 10,000, unit cost of 40 and price of 100, at least 167 whole units are needed. Keep currency and period consistent; account for taxes, returns and waste when relevant.
Why are some prices rejected?
If price does not exceed variable cost, sales cannot cover fixed costs in this model.