v0.10.0How to use
- Enter sales (selling price, quantity, buyer-paid shipping), cost (product cost, packaging), fees, and other costs (seller-paid shipping, ad spend, discount or coupon) on the basis shown in each label. Amounts are per unit in KRW; if one order ships several units, divide the per-order amount into a per-unit share.
- Enter the percentage fee (%) and the fixed fee (KRW per unit) separately. Check your sales channel's guidance to choose whether the percentage fee is charged on the price before or after the discount, and whether it also applies to buyer-paid shipping.
- For ad spend, choose "Per unit" or "Total (for this whole quantity)". Enter a target margin to also get the selling price per unit that reaches it.
- The key results at the top (profit, margin, profit per unit, break-even price), the price breakdown bar, the quantity comparison and the detailed results update as you type.
Example
With a selling price of 10,000, a cost of 6,000, seller-paid shipping of 2,500, packaging of 300, a percentage fee of 3.3% and a quantity of 1, the percentage fee is 330, total costs are 9,130 and profit is 870. The margin is 8.70% and the return on cost is 14.50%, and the lowest price at which profit is 0 or more is 9,100. With the same costs, the price needed for a 20% target margin is 11,474. Add a seller-paid coupon of 1,000 (fee on the price before discount) and the amount paid becomes 9,000 and profit -130, a loss. Values such as the fee rate are only examples and differ between sales channels, so check and enter them yourself.
How it is calculated
| Item | Calculation |
|---|---|
| Amount paid (sales) | (Price − discount or coupon + buyer-paid shipping) × quantity |
| Percentage fee | Total fee base × fee rate (rounded once). You choose the base: price before or after discount, with or without buyer-paid shipping |
| Fixed fee | Fixed fee × quantity |
| Ad spend | Per unit: ad spend × quantity; total: the amount entered as is |
| Total costs | Cost, seller-paid shipping and packaging (each × quantity) + fees + ad spend |
| Profit | Amount paid − total costs (before tax) |
| Margin | Profit ÷ amount paid |
| Return on cost | Profit ÷ (cost × quantity) |
Fees for each sales channel and tax rules change often, so check the latest guidance from the channel and a tax professional before you settle.
Supported formats, limits and privacy
- Input: whole amounts of 0 or more (in KRW, commas allowed), a quantity of 1 or more, a fee rate from 0 to 100% and a target margin of 0 or more but under 100 (up to two decimal places). Each amount can be up to 999,999,999,999 and the quantity up to 999,999,999 units. The discount or coupon cannot exceed the selling price.
- This is a simple calculator that works only from the values you enter. Profit is before tax: it does not account for taxes such as VAT or income tax, a platform's settlement method or schedule, or returns and refunds, so it can differ from the amount actually settled. Enter only the part of a discount or coupon that you pay. Do not use it for tax or accounting decisions.
- No platform fee rates are filled in for you. Check your sales channel's latest fee notice yourself and enter the rate. Whether the fee is charged before or after the discount, and whether it also applies to buyer-paid shipping, differs between channels, so you choose it yourself (default: price before discount, not charged on buyer-paid shipping).
- Margin is profit divided by the total amount paid (price − discount or coupon + buyer-paid shipping, each × quantity). Return on cost is profit divided by the total product cost.
- Rounding: amounts below one won are rounded half up (0.5 and above rounds up; negatives are rounded by absolute value). The percentage fee is calculated once on the total fee base and rounded only once. Margin and return on cost are rounded to two decimal places (0.01%), and profit per unit to the whole won. All arithmetic uses integers, so there are no floating-point errors.
- The break-even price is the lowest price per unit (in whole won) at which profit is 0 or more with the current quantity and costs, and the break-even quantity is the smallest quantity at which profit is 0 or more at the current price. The target-margin price is the lowest price per unit at which the unrounded margin reaches the target; if the percentage fee plus the target margin is 100% or more, it is shown as unreachable. If ad spend is "Total" it stays the same as the quantity grows, and if it is "Per unit" it scales with the quantity.
- What you enter is calculated only inside this browser. It is not sent to a server or stored, and it disappears when you close the page.
Frequently asked questions
What is the difference between margin and return on cost?
Margin is profit divided by the amount paid (sales), and return on cost is profit divided by the cost. With a selling price of 10,000 and a profit of 870, the margin is 8.70%, and with a cost of 6,000 the return on cost is 14.50%. The same profit gives different figures because the base is different, so use the same base when you compare.
How do I enter shipping when the customer pays for it?
Put the shipping the customer pays at checkout in "Buyer-paid shipping" and the shipping you pay the carrier in "Seller-paid shipping". Buyer-paid shipping counts toward the amount paid, and seller-paid shipping is deducted as a cost. If your channel also charges the percentage fee on shipping, turn on "Apply the percentage fee to buyer-paid shipping too".
Are platform fees and taxes calculated automatically?
No. You have to enter the fee rate yourself, and taxes are not included. This tool only calculates the numbers you enter exactly; it does not check any platform's fees or tax rules.