Calculate each completed resale from the item record, not from memory. A $300 payment can feel like a $300 win until the original purchase and the trip to the parts store are included.
Use a simple reseller profit formula
Recorded profit = sale revenue − purchase cost − item expenses
If you charge separately for delivery, include that amount in revenue and include the delivery cost you want attributed to the item among its expenses. Use the same approach consistently across sales so comparisons remain meaningful.
A basic reseller profit example
- Sale price (revenue)
- $300
- Purchase cost
- − $150
- Repair and cleaning expense
- − $25
- Recorded profit
- $125
The seller received $300, but the item produced $125 after the recorded cost and expense. The original $150 is recovered capital, not new profit.
To try the formula with your own numbers, use the free reseller profit calculator. It works without an account and does not save the values you enter.
Decide which item expenses belong in the calculation
Track expenses that were incurred to prepare, sell, or complete that specific resale. Depending on the item and selling method, those may include:
- purchase price
- repair labor or replacement parts
- cleaning supplies used for the item
- platform or payment fees where applicable
- shipping materials and postage where applicable
- delivery or item-specific transportation expense
General business costs such as storage rent, software, tools, vehicle costs, and insurance may matter to the business overall, but assigning them to individual items requires a consistent accounting method. Do not casually mix them into some item records and omit them from others.
Revenue, recorded profit, and margin mean different things
Revenue
Revenue is the money received from the sale, before subtracting the investment and expenses. In the example, revenue is $300.
Recorded profit
Recorded profit is what remains after the item's recorded purchase cost and item expenses are deducted. In the example, recorded profit is $125.
Profit margin
Profit margin expresses profit as a percentage of revenue:
Profit margin = recorded profit ÷ revenue × 100
$125 ÷ $300 × 100 = 41.7% profit margin
Margin is useful for comparing sales of different sizes. A $200 profit on a $1,500 sale and a $100 profit on a $200 sale do not have the same margin or capital efficiency.
Return on investment
ROI compares profit with the money invested in the item. One simple item-level approach is:
ROI = recorded profit ÷ total item cost × 100
$125 ÷ ($150 + $25) × 100 = 71.4% ROI
Margin divides by revenue; ROI divides by investment. Label the number clearly rather than using the terms interchangeably.
Track profit item by item
A bank balance combines purchases, sales, ordinary bills, transfers, and personal timing. It cannot tell you which dresser, phone, or appliance was worth buying. Item-level records preserve the purchase cost when it is fresh, add repair and cleaning expenses as they occur, and close with the actual sale price.
This also exposes categories that produce impressive revenue but weak profit after parts and time. To create reliable source records, start with a consistent system for tracking reseller inventory from acquisition through sale.
Remember the cost of unsold inventory
Unsold inventory has not produced revenue or profit. A garage full of items may represent thousands of dollars that cannot fund the next purchase until those items sell. Review the purchase cost and age of unsold stock alongside completed-sale profit. An item with a promising margin can still be a poor use of cash if it sits indefinitely.
- Know the total purchase cost still tied up in active inventory.
- Find items that have been owned or listed the longest.
- Do not count asking-price value as revenue.
- Record sold status promptly so active inventory stays accurate.