What the main numbers mean
Cost is what the line costs you before you sell it. Sell price is the price being charged to the customer for that line. Profit is what is left after cost is taken away from revenue.
Margin shows profit as a percentage of revenue. Markup shows profit as a percentage of cost. They are related, but they are not the same. A line can look strong in pounds while still being weaker than expected in margin percentage.
How discount affects the line
Discount changes more than the final sell price. It also changes the profit and margin sitting underneath the line.
That is why Quotelixa treats discount as a pricing decision, not just a cosmetic reduction. The calculator helps you see what that movement actually costs before it gets hidden inside a larger quote.
The practical value
Use the line calculator when you need a fast answer on one line: cost, sell price, discount, tax treatment, profit, margin, markup, and whether the result still makes sense.
If the quote grows into customer output, internal review, competitor comparison, or repeat work, move into the wider Pro workflow.