Revenue minus the cost of goods sold is your gross profit — and gross margin tells you how much of every dollar survives COGS. See both, plus the markup you are actually charging.
Gross profit is what covers salaries, rent and everything else.
Don't confuse them: margin is % of revenue, markup is % of cost.
Healthy margins vary by industry — software runs high, grocery runs low.
All calculations happen locally in your browser.
Know your numbers cold.