Most resellers don't actually know if they're profitable. They see money coming in from sales and assume it's profit. Then they're confused when their bank account doesn't reflect the "success" they think they're having.
The reality, as we covered in Is Thrift Flipping Actually Profitable?, is that revenue and profit are very different things. Tracking the difference isn't complicated—it just requires a simple system you actually use.
Here's a straightforward spreadsheet method that takes 30 seconds per item and tells you everything you need to know.
The Essential Columns
Your tracking spreadsheet needs these columns at minimum:
| Column | What to Track |
|---|---|
| Date Purchased | When you bought the item |
| Item Description | Brief description (brand, type, size) |
| Cost | What you paid for the item |
| Platform | Where you listed/sold it |
| Date Listed | When you published the listing |
| Date Sold | When it sold (blank until sale) |
| Sale Price | What buyer paid (before fees) |
| Shipping Cost | Your actual shipping expense |
| Platform Fees | Commission + payment processing |
| Profit | Sale Price - Cost - Shipping - Fees |
That's it. Ten columns. You can add more later, but this captures the essential data.
The Profit Formula
The only formula you need:
In spreadsheet terms, if Sale Price is column G, Cost is column C, Shipping is column H, and Fees is column I:
This gives you the actual profit for each item. No guessing, no approximating, no "I think I made about..."—real numbers.
When to Log Entries
At Purchase
Log the item immediately when you buy it. Fill in: Date Purchased, Item Description, and Cost. Takes 10 seconds. Do this while still in the thrift store if needed—otherwise items get forgotten.
At Listing
Add the Date Listed and Platform. This helps you track time-to-list (are items sitting in your death pile?) and see which platforms you're using most.
At Sale
Fill in Date Sold, Sale Price, Shipping Cost, Platform Fees, and let the formula calculate Profit. Most of this info comes from the sale confirmation email.
Tip: Create a new row for each item at time of purchase, even if other columns stay blank. This ensures you track inventory that hasn't sold yet—crucial for understanding what's sitting unsold.
What the Data Tells You
Once you have a few weeks of data, patterns emerge:
Average Profit Per Item
Add up the Profit column, divide by number of sales. If your average profit is $15 and you want to make $500/month, you need about 34 sales. This makes goals concrete.
Best Performing Categories
Which types of items have the highest profit margins? You might discover that the jackets you love sourcing only average $12 profit while shoes you ignored average $25. Adjust accordingly.
Platform Comparison
Does the same item perform differently on eBay vs. Poshmark? Your data will show real differences, not assumptions.
Time to Sell
Days between listing and sale reveals how quickly inventory moves. Items taking 60+ days might need price drops or shouldn't be purchased again.
Death Pile Detection
Items with a Purchase Date but no List Date are sitting unlisted. If that number keeps growing, you have a problem.
Sample Layout
Here's what a few rows might look like:
| Purch. | Item | Cost | Platform | Sold | Sale $ | Ship | Fees | Profit |
|---|---|---|---|---|---|---|---|---|
| 1/5 | Patagonia Fleece L | $8 | eBay | 1/12 | $65 | $9 | $9 | $39 |
| 1/5 | Gap Jeans 32x30 | $6 | Poshmark | 1/18 | $28 | $0 | $6 | $16 |
| 1/8 | Nike Windbreaker M | $5 | — | — | — | — | — | — |
The Nike Windbreaker shows as unlisted (no platform, no sale date). That's data too—you know something needs attention.
Monthly Summary
At month end, create a simple summary:
- Total Revenue — Sum of Sale Price column
- Total Cost of Goods — Sum of Cost column (for sold items)
- Total Fees — Sum of Platform Fees column
- Total Shipping — Sum of Shipping Cost column
- Total Profit — Sum of Profit column
- Items Sold — Count of completed sales
- Items Purchased — Count of new inventory
- Items Listed — Count of new listings
This takes 5 minutes and gives you a real picture of your business. You'll also need this data for tax purposes.
Tools to Use
Google Sheets is the go-to for most resellers. It's free, works on any device, syncs automatically, and handles all the formulas you need. Start here.
Excel works identically if you prefer Microsoft's ecosystem or work offline.
Dedicated apps exist (like Seller Toolkit, Resale Rabbit, etc.), but they're often overkill for beginners and cost money. Start with a spreadsheet, understand what data matters to you, then evaluate apps later if you outgrow the simple approach.
The Habit That Matters
The best system is the one you actually use. A simple spreadsheet updated consistently beats an elaborate system you abandon after two weeks.
Build the habit early. Log every purchase immediately. Update sales daily or weekly. Review monthly numbers at month end. The data compounds—after three months, you'll have insights that transform your sourcing decisions.
You can't improve what you don't measure. Start measuring today.