The short answer
Keep every price list your supplier sends, compare each new one with the last on a fixed schedule, and write down what changed. How you do that depends on how the prices reach you. A price list by email suits a monthly spreadsheet routine. A file at a web address can be checked automatically. A supplier with no file at all needs a different plan.
Why price changes slip through
A supplier rarely tells you about each change. A new list arrives with the same file name, 2,000 rows look much like last month, and the one line that matters is somewhere in the middle. The first sign is often an invoice that does not match, or a margin report weeks later.
A cost rise you miss does not show up as an error. Your store keeps selling at the old price, and each sale simply earns less. A 10% cost rise on a product with a 30% margin takes that margin to 23%, even though nothing looks wrong.
Start with how your supplier sends prices
| How prices arrive | What works | Main drawback |
|---|---|---|
| Spreadsheet by email, now and then | Compare two files by hand in Excel | You must remember to do it |
| CSV at a web address or feed link | A scheduled check that compares each day | The supplier has to publish a file |
| PDF price list | Convert to a table first, then compare | Conversion errors, so check totals |
| Supplier portal only | Export on a schedule if the portal allows it | Often manual, and check the portal terms |
| Prices only appear on invoices | Compare invoices with your purchase orders | You find out after buying |
A simple monthly routine
If your supplier emails a list, a repeatable routine beats a clever tool. It takes less time than chasing a margin problem later.
- Save every list with its date. Use a name such as
acme-prices-2026-11-01.csvand never overwrite the old one. The dated files are your price history. - Compare with the previous list. The guide to comparing two supplier price lists in Excel gives the exact formulas.
- Log what changed. One row per change: date, supplier, SKU, old cost, new cost.
- Decide on each large change. Choose a threshold, such as 5%, and look at everything above it.
- Update your selling prices in one batch. Then record that you did.
What to do when a price changes
A cost change is not automatically a price change. Go through these in order.
- Confirm it. A large jump can be a typo, a new pack size or a currency change. Ask the supplier before you act.
- Check the margin. Use the markup and margin calculator to see what the new cost does to your margin. If you are unsure which number you are looking at, markup and margin are not the same.
- Choose a response. Raise the price, absorb the cost for now, change supplier or drop the product.
- Update the store safely. On Shopify, follow the supplier CSV update guide and keep a way to roll the import back.
Keep cost and selling price apart
A supplier list usually contains your cost, not your selling price. Keep the two in separate columns. If your store records a cost per item, update it too, or your own profit reports will drift from reality. Note that cost alone is not profit: shipping, payment fees, discounts and tax all come out of the same sale.
Options if you want this automated
Shopify apps can keep a cost history and alert you to changes. Inventory sync apps can also pull supplier feeds and change your store for you, which saves time but means a bad file can reach your prices directly. Before you install one, check its current price and reviews, and look at what it does when a file is wrong.
Supplier Price Watch is our version of the read-only approach. It reads a supplier CSV from a web address once a day, emails you what changed, and refuses a file that looks broken instead of treating it as real. It never changes your store. It suits a supplier who publishes a file. It does not read PDFs or inboxes, so if your prices arrive by email, the monthly routine above is the better fit today.
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