The number of units that pays your fixed costs

What it is: How many units you must sell each month before the line earns anything at all.
Why it matters: Below it, every month costs you money no matter how busy you are. Above it, every extra unit is almost all margin. It is the sharpest line in small business and most people running one have never worked it out.
The method: Fixed costs divided by margin per unit, rounded up. If the margin is zero or negative there is no break-even — selling more makes the loss bigger, and the price or the cost has to move first.
Example: PKR 45,000 of fixed costs against PKR 380 of margin is 119 units. At 300 units he is comfortably past it. At 100 he would have been losing money while working hard.

Where the two are level is break-even. Everything past it is yours.

Now you

Fixed costs, and margin on one unit.