A painter just received a trade supplier invoice for materials at $1,840. They apply a 30% markup to materials when billing clients. Before the final invoice goes out, they need the client price and the GST-inclusive total.
Selling = Cost × (1 + Markup%) · Margin = Profit ÷ Sell
A 25% markup gives a 20% margin — markup is always higher than the equivalent margin.
1 What this calculator does
Calculates the selling price from a cost price and markup percentage (or the sale price from a regular price and discount percentage). In markup mode: shows profit, GST component and GST-inclusive price. In discount mode: shows customer saving and final sale price.
2 Formula & professional reasoning
Markup mode:
Selling price = Cost x (1 + Markup% / 100)
Profit = Selling price - Cost
GST = Selling price x 0.10 (or custom tax %)
Inc. tax price = Selling price x (1 + Tax% / 100)
Discount mode:
Sale price = Regular price x (1 - Discount% / 100)
Customer saving = Regular price - Sale price
Markup is calculated on cost (cost is the base). Margin is calculated on revenue (selling price is the base). A 30% markup on $1,840 cost gives $1,840 x 1.30 = $2,392 selling price. The profit is $552, which is 30% of cost. The gross margin percentage is $552/$2,392 = 23.1% -- margin is always lower than markup. This distinction matters for financial reporting and understanding true profitability.
3 Worked examples
⚠️ Illustrative example only — not clinical or professional instruction.
Selling price: $1,840 x 1.30 = $2,392 | Profit: $2,392 - $1,840 = $552 | GST: $2,392 x 0.10 = $239.20 | Inc. GST: $2,392 x 1.10 = $2,631.20Sale price: $4,500 x 0.75 = $3,375 | Saving: $4,500 - $3,375 = $1,12525% margin means profit = 25% of selling price | So cost = 75% of selling price | Selling price: $800/0.75 = $1,066.67 | This is NOT the same as 25% markup: $800 x 1.25 = $1,0004 Sanity check
5 Common errors
| Error | Cause | Consequence | Fix |
|---|---|---|---|
| Confusing markup and margin -- using margin% as a markup% | Not understanding the difference | Underpricing -- intended 30% margin becomes 23.1% margin | Significant profit leakage | For 30% gross margin: selling price = cost / (1 - 0.30) = cost / 0.70. For 30% markup: selling price = cost x 1.30. 30% margin requires a 42.9% markup. Always confirm which basis the percentage refers to. |
| Not adding GST after the markup | Treating markup as the final price | Invoice excludes GST -- under-collecting tax if GST-registered | If you are GST-registered, always add GST after the markup. Client price = (Cost x markup factor) x 1.10. The GST is collected on behalf of the ATO and is not your revenue. |
| Applying markup to the GST-inclusive cost price | Not stripping GST before applying markup to the cost | Markup applied to a larger base -- overcharging clients on materials | When you purchase materials, your cost is the GST-exclusive (ex-GST) price because you claim the input tax credit. Apply markup to the ex-GST cost. Then add GST to the marked-up ex-GST selling price. |
| Undercharging for materials by not applying any markup | Passing through materials at cost to appear competitive | No recovery for the time, effort and risk in sourcing and purchasing materials | Gross margin understated | Materials markup is legitimate and expected in the trades. A 20-30% markup on materials is industry standard. The markup recovers purchasing time, credit risk, delivery, handling and warranty claims. |
6 Reference & regulatory links
7 Professional workflow
Common tools used alongside this one: