Buy Price to Net Profit
"I bought it for $5 and sold it for $40" is a story, not a number. Net profit is what's left after every hand has taken its cut — and your time is one of those hands.
Per-item profit calculator
Enter your numbers. Use the current fee rate from your platform's seller fee page. Everything runs in your browser; nothing is sent anywhere.
Every line on the ledger
Here's the full formula we use for every item:
Net = Sale price − Buy price − Platform fees − Payment processing − Shipping you pay − Supplies − Travel share
Then divide net by the minutes you spent (sourcing share, cleaning, photographing, listing, answering questions, packing, dropping off) and multiply by 60. That's your real hourly rate.
Fees are calculated on more than the item
Several marketplaces charge their percentage on the total the buyer pays, including shipping and sometimes sales tax. A $40 item with $10 shipping can carry a fee on $50, not $40. Read the fee page closely.
Shipping is the silent margin killer
Weigh before you list. A sweater that tips over a weight tier can cost several dollars more to ship. A cheap postal scale pays for itself within weeks. Services like USPS Ground Advantage and discounted label tools such as Pirate Ship can help on lightweight parcels — compare rates before you print.
Supplies add up
Poly mailers, tissue, tape, labels and printer ink feel like pennies. Over 300 sales a year they're a real line. Reuse clean boxes and buy mailers in bulk.
Time is the line most people skip
An item that nets $7 but takes 30 minutes pays $14 an hour. Plenty of flippers discover their "side hustle" pays less than a part-time job because they never timed it. Track minutes for a month and you'll know which categories to drop.
Worked examples
| Item | Buy | Sold | Fees | Ship | Supplies + travel | Net | Minutes | Per hour |
|---|---|---|---|---|---|---|---|---|
| Wool overcoat | $12.00 | $90.00 | $13.00 | $14.00 | $3.00 | $48.00 | 40 | $72.00 |
| Cast iron skillet (local) | $6.00 | $35.00 | $0.00 | $0.00 | $3.00 | $26.00 | 30 | $52.00 |
| Graphic tee | $2.50 | $18.00 | $3.00 | $0.00 | $0.75 | $11.75 | 15 | $47.00 |
| Novelty mug | $1.50 | $12.00 | $2.00 | $6.50 | $1.50 | $0.50 | 20 | $1.50 |
Fee figures above are illustrative assumptions for the example, not quotes from any platform.
Taxes and records
Reselling profit is generally taxable income. Payment platforms may issue a Form 1099-K, and the IRS reporting thresholds have changed several times in recent years — check IRS.gov for the year you're filing. Whatever the threshold, keep receipts or a log of every buy price, because that's how you show the cost against the sale. We're not tax advisors; a qualified professional can tell you what applies to you.