What is the Sales Calculator?
This all-in-one sales calculator unifies the margin, markup, price and profit tools into a single form. It works with five linked variables: cost (what you pay), revenue (your selling price), gross profit (revenue minus cost), gross margin (profit as a percent of revenue) and markup (profit as a percent of cost). Enter any two of them and the calculator solves the remaining three. The math is universal business arithmetic, so the currency is just a label and the tool applies anywhere.
How to use it
Fill in exactly two fields and leave the others blank. At least one of the two must be a currency amount — Cost, Revenue or Gross Profit — because margin and markup are only ratios and cannot fix actual amounts on their own. Percentages are entered as whole numbers (40 means 40%). Click calculate and read the full breakdown of all five values.
The formula explained
Three identities drive everything: gross profit \(P = R - C\), margin \(M = P / R\), and markup \(K = P / C\). From these you can rearrange: revenue from cost and margin is $$R = \frac{C}{1 - M}$$ revenue from cost and markup is $$R = C \times (1 + K)$$ and margin and markup convert with $$M = \frac{K}{1 + K}$$ The key distinction people miss is that margin divides by revenue while markup divides by cost, so the same profit gives a smaller margin percentage than markup percentage.
Worked example
Suppose cost = 100 and gross margin = 40%. Then $$R = \frac{100}{1 - 0.40} = 166.67$$ $$P = 166.67 - 100 = 66.67$$ $$K = \frac{66.67}{100} = 66.67\%$$ So a 40% margin equals a 66.67% markup on the same item.
FAQ
What is the difference between margin and markup? Margin is profit as a share of the selling price (revenue); markup is profit as a share of the cost. A 50% markup is only a 33.33% margin.
Why can't I enter only margin and markup? Both are ratios with no dollar anchor, so the absolute cost, revenue and profit are undetermined. Add any one currency value to solve the rest.
Can profit be negative? Yes — if you sell below cost, gross profit, margin and markup all turn negative, which the calculator handles.
