What this calculator does
This gross margin calculator converts turnover and cost of sales into the three figures pricing decisions rest on: gross profit in pounds, gross margin as a percentage of turnover, and the equivalent markup on cost. Enter what you sold for and what it cost to supply, and it returns all three alongside a table mapping markup against margin at different levels.
Gross margin measures the profitability of what you sell, before any overhead. Its narrowness is the point — it isolates whether the product itself earns money, quite separately from whether the company as a whole is trading profitably this year.
When to use it
The usual trigger is a pricing review. Working backwards from a target margin produces a defensible figure rather than an instinct, and it is the only reliable way to confirm that a price rise actually delivers the profit intended once you have allowed for the volume you may lose.
It is equally the right tool for a mix question. Where two lines sell at similar prices but one returns 55 percent and the other 22, they should not receive equal attention from the sales team. Run each separately and use the comparison to decide what to promote, what to reprice, and what to withdraw.
Understanding the inputs
Turnover should be net of VAT, discounts, and returns — money retained rather than money invoiced. A healthy returns rate hidden inside a gross figure will overstate margin by several points and quietly distort every decision that follows.
Cost of sales includes only costs that vary with volume: materials, inbound carriage, direct labour, and card fees. Rent, business rates, administrative salaries, and marketing belong below the gross profit line. The unit cost field drives the markup table, so enter a fully loaded unit cost rather than materials alone if you intend to use the resulting prices.
How is this calculated?
Gross Profit = Revenue − COGS. Gross Margin % = (Gross Profit / Revenue) × 100. Markup = (Gross Profit / COGS) × 100.
A worked example
A wholesaler reports £250,000 of annual turnover against £150,000 of cost of sales. Gross profit is £100,000, gross margin is 40 percent, and the equivalent markup on cost is roughly 67 percent. Every pound of sales leaves 40 pence to meet rent, wages, and overheads before any profit reaches the bottom line.
If supplier renegotiation cuts cost of sales to £137,500, margin rises to 45 percent and gross profit to £112,500 — £12,500 more with no additional trading. Winning that same £12,500 through growth at the original 40 percent margin would take about £31,000 of extra turnover, a considerably harder year.
Limitations and assumptions
Gross margin tells you nothing about overall profitability. A company can hold an 80 percent gross margin and still post a loss in its statutory accounts if overheads exceed gross profit, which is the ordinary state of most early-stage software businesses.
The figure is only as reliable as your cost classification, and genuine judgment sits in the boundary — particularly around support costs, subcontractors, and warehousing. Shift an item across the line and margin moves without anything real changing. If the number will appear in accounts filed at Companies House or in a lending application, agree the treatment with your accountant and apply it consistently year to year.
Common Questions
- What is the difference between margin and markup?
- Margin expresses profit as a percentage of the selling price; markup expresses it as a percentage of cost. The same pounds, measured from opposite ends. A 40 percent margin equals a 67 percent markup, while a 50 percent markup yields only a 33 percent margin — a confusion that quietly underprices a great many businesses.
- Should turnover be recorded before or after VAT?
- Before. VAT is collected for HMRC and never forms part of turnover in your profit and loss account, so including it inflates the margin calculation. Use net figures on both sides — turnover excluding output VAT and cost of sales excluding recoverable input VAT — so the two are consistently stated.
- What belongs in cost of sales?
- Only costs that move with what you sell: materials, inbound carriage, direct production labour, and for software the hosting and support attributable to serving customers. Rent, business rates, marketing, and administrative salaries are overheads and sit below gross profit in the profit and loss account, not within cost of sales.
- What gross margin should I be aiming for?
- It depends heavily on sector, so treat benchmarks loosely. As a common rule of thumb, software businesses target 70 to 85 percent, professional services 40 to 60, manufacturing 25 to 40, and food retail often runs under 25. The useful comparison is against your own sector and your own prior year.
- Do card processing fees belong in cost of sales?
- Yes. Fees of 1.5 to 3 percent scale directly with turnover and behave exactly like a cost of sale. Omitting them overstates gross margin by a couple of points, which matters once you are managing to a target rather than simply watching the trend.
- Turnover rose but gross margin fell. Why?
- Almost always mix or discounting rather than input prices. Growth concentrated in lower-margin lines, larger customers negotiating harder terms, or a promotion that ran too long will all lift turnover while diluting margin. Break the figure down by product and by customer before blaming suppliers.
- How much is a single percentage point of margin worth?
- More than most owners expect, because it falls straight to gross profit. On £300,000 of turnover, one point is £3,000 of profit with no extra sales, no additional delivery cost, and no new customers to win. Very few operational projects return that much for the effort involved.
- Can I price from a target margin?
- Yes, by working backwards. Divide the unit cost by one minus the target: a £20 item at a 45 percent target prices at about £36.36 before VAT. This is exactly where margin-markup confusion costs money, since adding 45 percent to cost would give £29 and a margin of only 31 percent.
- How does gross margin limit what I can spend on marketing?
- It sets the ceiling, because only gross profit is available to fund overheads and customer acquisition. A business running at 30 percent has thirty pence per pound of turnover to work with, so an acquisition cost that looks modest against turnover can be unaffordable when set against gross profit.