How to Calculate True Net Profit as a Marketplace Seller (No BS Guide)
10 min read
Last month, SKU B07X6K89P lost 12% margin because we forgot to add the $3.20 Amazon referral fee to the spreadsheet. That’s $1,800 gone. We fixed it by recalculating true net profit across 10 marketplaces, not just revenue minus product cost. Here’s exactly how we did it—and how you can avoid the same mistake.
Why Your Spreadsheet Lies to You (And How to Stop It)
Most sellers start with revenue minus product cost and call it profit. That’s like saying a $20 shirt costs $10 because you paid $10 for it. You’re ignoring the $4 Amazon referral fee, the $3.50 shipping Amazon charges the buyer, the 15% ad spend, and the $12 refund the customer filed after the shirt arrived two days late.
True net profit isn’t revenue minus product cost. It’s revenue minus every single cost tied to that SKU: platform fees, shipping, ads, refunds, currency conversion, storage, and even the 2.9% payment processing fee on Shopify. If you’re not tracking these, your margin is fiction.
We learned this the hard way with SKU B07X6K89P. Revenue looked healthy at $15,000 last month, but after adding $4,800 in fees, $2,100 in ads, $1,200 in refunds, and $1,500 in shipping, the real profit was $5,400—36% margin, not the 60% we thought. That’s the difference between guessing and knowing.
The 5 Cost Buckets You Can’t Ignore
Break every SKU into five buckets. Miss one, and your profit is wrong.
1. Product cost: What you pay the supplier or manufacturer. Include landed cost—freight, customs, duties, and any prep fees the supplier charges. SKU B07X6K89P’s landed cost was $7.80, not the $6.50 we listed in the spreadsheet.
2. Platform fees: Amazon’s referral fee (15% for most categories), eBay’s final value fee (10-15%), Etsy’s 6.5% transaction fee plus $0.20 listing fee, TikTok Shop’s 2-5% commission. Shopify’s 2.9% payment processing fee isn’t a platform fee, but it’s a cost you can’t skip.
3. Shipping: What you pay to ship the item to the customer. Amazon FBA charges $3.50 for standard shipping, but if you’re fulfilling yourself, you’re paying $4.20 for USPS Priority Mail. Temu’s free shipping isn’t free—it’s baked into the product cost, but you still need to track it.
4. Advertising: Amazon PPC, TikTok Spark Ads, Walmart Sponsored Products, Google Shopping. SKU B07X6K89P spent $2,100 on ads last month, but only $1,200 converted to sales. The rest was wasted spend.
5. Refunds and chargebacks: The $12 refund for the late shirt, the $5 chargeback fee when the customer disputed the charge, the 10% restocking fee on returned items. These add up fast. Last month, refunds cost us $1,200 across 87 orders.
Multi-Currency? Convert Everything to One Base Currency
If you sell on AliExpress, Shopee, or Lazada, you’re dealing with multiple currencies. A $10 sale on Shopee might be 70 MYR, but your supplier charges in USD. Convert everything to USD (or your home currency) before calculating profit.
Here’s how: - Use real-time exchange rates from the day of sale. Don’t use last month’s average—it’s wrong. - If you’re using a tool like Gomarginify, it does this automatically. If you’re doing it manually, use XE.com or your bank’s rate. - Round to two decimal places. A 0.1% difference in exchange rate can swing your margin by 0.5% on high-volume SKUs.
We switched from manual conversion to automatic in March. SKU B07X6K89P’s profit jumped from $5,400 to $5,600 because we stopped losing 0.3% on every sale due to outdated rates.
The 4 Tools That Do the Heavy Lifting (And One You Should Avoid)
You can calculate true net profit in Excel, but it’s a nightmare. You’ll spend hours pulling data from 10 marketplaces, matching SKUs, and fixing formula errors. Instead, use a tool that automates the process.
1. Gomarginify: Connects 10 marketplaces (Amazon, Shopify, TikTok Shop, Temu, eBay, Etsy, Walmart, AliExpress, Shopee, Lazada) and calculates true net profit per SKU daily. It pulls in platform fees, shipping, ads, refunds, and currency conversion automatically. We switched to it in March and cut our margin calculation time from 4 hours to 10 minutes.
2. Sellerboard: Good for Amazon-only sellers. It tracks PPC spend, refunds, and fees, but it doesn’t handle multi-marketplace or multi-currency.
3. Shopify Analytics + Google Sheets: If you’re Shopify-only, you can pull order data, ad spend from Google Ads, and payment fees from Shopify, then calculate profit in Sheets. It’s free but manual and error-prone.
4. QuickBooks Commerce: Syncs with Shopify, Amazon, and eBay, but it’s overkill for most sellers and doesn’t handle TikTok Shop or Temu.
Avoid spreadsheets for multi-marketplace sellers. They lie to you. We’ve seen sellers lose $5,000 a month because they forgot to add a single fee category.
Step by step
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Step 1: Pull Raw Data from Every Marketplace
Start with a clean slate. Pull the last 30 days of sales data from every marketplace you sell on. Export it as CSV or Excel files.
- Amazon: Go to Reports > Fulfillment > Amazon Fulfilled Shipments. Download the "Sales" report. - Shopify: Go to Analytics > Reports > Sales by product. Export as CSV. - TikTok Shop: Go to Shop Manager > Orders > Export orders. - Temu: Go to Seller Center > Orders > Export. - eBay: Go to Seller Hub > Orders > Download orders. - Etsy: Go to Shop Manager > Orders > Export orders. - Walmart: Go to Seller Center > Reports > Order reports. - AliExpress: Go to Seller Center > Orders > Export orders. - Shopee: Go to Seller Center > Orders > Export orders. - Lazada: Go to Seller Center > Orders > Export orders.
If you’re using a tool like Gomarginify, skip this step—it pulls the data for you. If you’re doing it manually, make sure you’re exporting SKU-level data, not just order-level data. You need to see every sale, refund, and fee per SKU.
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Step 2: Match SKUs Across Marketplaces (This Is Where Most Sellers Fail)
SKU B07X6K89P on Amazon is listed as "B07X6K89P" in Shopify, but on TikTok Shop it’s "TIK-89P-B07X". If you don’t match these correctly, your profit calculation is garbage.
Here’s how to match SKUs: - Use a consistent naming convention across all marketplaces. If your Amazon SKU is "B07X6K89P", use the same on Shopify, TikTok Shop, and everywhere else. - If you can’t change the marketplace SKUs, create a mapping table in Excel. Column A is the marketplace SKU, Column B is your internal SKU. - Double-check the mapping. One wrong match and your entire profit calculation is off. We once matched "B07X6K89P" to "B07X6K89" and lost $800 in fees because the system thought it was a different product.
If you’re using Gomarginify, it matches SKUs automatically. If you’re doing it manually, set aside 30 minutes to verify every match.
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Step 3: Add Every Cost to the Spreadsheet (Or Let the Tool Do It)
For each SKU, add the five cost buckets we talked about earlier. If you’re using a tool, it’ll pull most of this data automatically. If you’re doing it manually, here’s what to add:
- Product cost: Landed cost, including freight, customs, and duties. - Platform fees: Amazon’s 15% referral fee, eBay’s 10-15% final value fee, TikTok Shop’s 2-5% commission, etc. - Shipping: What you pay to ship the item to the customer. For FBA, it’s $3.50. For self-fulfillment, it’s whatever you pay USPS, DHL, or your courier. - Advertising: Amazon PPC, TikTok Ads, Google Shopping, etc. - Refunds: The amount refunded to the customer, plus any restocking fees or chargeback fees.
Here’s a real example for SKU B07X6K89P last month: - Revenue: $15,000 - Product cost (landed): $7,800 - Platform fees: $2,250 (15% of $15,000) - Shipping: $1,500 ($3.50 per order x 429 orders) - Advertising: $2,100 - Refunds: $1,200 - True net profit: $15,000 - $7,800 - $2,250 - $1,500 - $2,100 - $1,200 = $150
That’s a 1% margin, not the 60% we thought. The spreadsheet lied to us.
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Step 4: Convert Currency and Calculate True Net Profit
If you’re selling in multiple currencies, convert everything to your base currency (USD, EUR, etc.) before calculating profit.
Here’s how: - For each sale, convert the revenue and costs to your base currency using the exchange rate on the day of sale. - If you’re using a tool like Gomarginify, it does this automatically. If you’re doing it manually, use XE.com or your bank’s rate. - Round to two decimal places. A 0.1% difference in exchange rate can swing your margin by 0.5% on high-volume SKUs.
For SKU B07X6K89P, a sale in MYR (70 MYR) at an exchange rate of 0.22 USD/MYR is $15.40. If you used last month’s average rate of 0.21, you’d calculate the sale as $14.70, losing $0.70 per sale. On 429 orders, that’s $300 gone.
After converting everything, recalculate the true net profit: - Revenue: $15,000 (converted from multiple currencies) - Product cost: $7,800 (converted) - Platform fees: $2,250 (converted) - Shipping: $1,500 (converted) - Advertising: $2,100 (converted) - Refunds: $1,200 (converted) - True net profit: $1,150
That’s a 7.7% margin, not the 1% we calculated before conversion.
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Step 5: Set Up Daily Profit Reports (So You Never Guess Again)
True net profit isn’t a monthly exercise. It’s a daily habit. If you’re not tracking profit in real time, you’re flying blind.
Here’s how to set up daily profit reports: - Use a tool like Gomarginify to send daily profit reports via email, Slack, or Discord. It’ll show you true net profit per SKU, losing SKUs, low margins, and high refund rates. - If you’re doing it manually, pull the last 24 hours of sales data from each marketplace, update your spreadsheet, and recalculate profit. It’s tedious, but it’s better than guessing. - Set up alerts for SKUs with margins below 10%. SKU B07X6K89P’s margin dropped to 5% last week because ad spend spiked. We caught it in real time and paused the campaign before it cost us more.
The goal is to know your profit before you spend another dollar on ads, inventory, or supplier negotiations. If you’re not doing this, you’re leaving money on the table.
FAQ
Do I really need to track refunds and chargebacks separately, or can I just use the net revenue after refunds?
You need to track refunds and chargebacks separately because they’re real costs, not just revenue adjustments. A $12 refund isn’t just revenue lost—it’s $12 you paid to the customer, plus any restocking fee, plus any chargeback fee. If you only track net revenue, you’re understating your costs by 10-20%. SKU B07X6K89P’s refunds cost us $1,200 last month, but net revenue only dropped by $900. The difference was fees and restocking costs.
How do I handle Amazon FBA storage fees and long-term storage fees in my profit calculation?
Amazon FBA storage fees are part of your platform fees. They’re not separate costs you need to add manually. The FBA fees you see in your Amazon reports already include storage fees. If you’re using a tool like Gomarginify, it pulls these fees automatically. If you’re doing it manually, make sure you’re including the "FBA Fees" line item in your Amazon reports. Long-term storage fees are rare for most sellers, but if you have them, add them as a separate line item under platform fees.
I sell on TikTok Shop and Temu. Their fees are lower than Amazon’s, but I’m still losing money. Why?
TikTok Shop and Temu’s fees are lower, but their shipping and refund policies can kill your margin. TikTok Shop’s free shipping isn’t free—it’s baked into the product cost, but you still need to track it. Temu’s refund policy is buyer-friendly, so refund rates are higher. SKU B07X6K89P’s refund rate on Temu was 8%, compared to 3% on Amazon. That’s why your margin is lower. Track refund rates per marketplace, not just fees.
Track your real profit across every marketplace
Stop guessing your margins. This step-by-step breaks down how to calculate true net profit across Amazon, Shopify, TikTok Shop, and 7 other marketplaces—with real numbers and common pitfalls sellers miss.
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