Amazon Flat File Upload: A Step-by-Step Guide to Bulk Listing
Adding products one at a time in Seller Central works for a handful of SKUs. Past about 20, or as soon as you have variations like sizes and colours, a spreadsheet upload is faster and less error-prone. Amazon calls these inventory files; sellers usually call them flat files.
This guide walks through the process as it works in Seller Central today. Amazon changes its templates and menus regularly, so if a label below doesn't match what you see, look for the closest equivalent.
1. Know what you're uploading
Before downloading anything, decide which of these you're doing:
- Creating new ASINs. The product doesn't exist on Amazon yet, usually your own brand.
- Matching existing ASINs. You're a reseller adding an offer to a product that's already in the catalog.
- Updating listings. Changing titles, bullets, attributes or images on listings you already manage.
The columns you must fill differ for each, and mixing them in one file is a common source of errors.
2. Download the right category template
In Seller Central, go to Add Products via Upload (under the Catalog or Inventory menu, depending on your account), then download an inventory file template. Choose the marketplace and browse to the exact product category.
The template must match your product's category. Each category has its own required attributes, and a template from the wrong category is one of the fastest ways to get upload errors, or to overwrite attributes on existing listings.
If your products span several categories, use one template per category.
3. Fill the required columns
Templates are long, but only some columns are required. Required fields are usually marked in the template's instructions or data definitions tab. The ones that matter in almost every category:
| Field | What it is | Common mistakes |
|---|---|---|
| Seller SKU | Your own unique code for the item | Reusing a SKU, or changing it later |
| Product ID and ID type | UPC, EAN, GTIN or ASIN | IDs not registered to your brand |
| Item name (title) | The product title | Over 200 characters, banned symbols, repeated words |
| Brand name | Exactly as registered | Different spelling from Brand Registry |
| Item type keyword / product type | Amazon's classification for browse placement | Too generic, which buries the product |
| Bullet points | Up to five key features | Promotional claims, prices, shipping promises |
| Price and quantity | Your offer | Left blank, so the listing is created inactive |
| Main image URL | A public link to the main image | Links that require login or expire |
Since January 2025, Amazon applies stricter title rules in most categories: a 200-character limit including spaces, no special characters such as ! $ ? { } unless they're part of the brand name, and no word used more than twice (small words like "and" or "for" excepted).
Product IDs
New products normally need a GTIN (UPC or EAN). If your brand doesn't use barcodes, you may qualify for a GTIN exemption, which you apply for in Seller Central before uploading. Buying cheap barcodes from resellers often leads to mismatches, because Amazon checks GTINs against the GS1 database.
4. Build variations properly
Variations (one product in several sizes or colours) use a parent-child structure:
- One parent row with no price or quantity. It just groups the children.
- One child row per sellable item, each with its own SKU, product ID, price and stock.
- On every child, the parent SKU, the relationship type (variation) and the variation theme, such as Size, Color or SizeColor.
- The variation values themselves, for example "Large" and "Navy".
The variation theme has to be one that the category allows. If you pick a theme the category doesn't support, the children upload as separate listings and the family breaks.
5. Upload and read the processing report
Back in Add Products via Upload, upload the completed file. Amazon processes it and produces a processing report, which you can download from the upload status page.
The processing report lists every row with errors or warnings and an error code. Fix the rows it flags and re-upload only those rows. Some patterns we see most often:
- Missing required attribute. A column the category needs is blank.
- Product ID conflicts. Your data disagrees with what Amazon already has for that GTIN or ASIN.
- Invalid value. A value isn't in the list Amazon accepts for that field. Check the template's valid values tab.
- Image problems. The URL can't be reached, or the image breaks main-image rules.
A clean report doesn't always mean a live listing. Check Manage All Inventory for listings that show as inactive, suppressed or awaiting stock.
6. Main image rules worth checking before you upload
The main image is the most frequent reason a listing gets suppressed after upload:
- Pure white background
- The product fills most of the frame, with no added text, logos or borders
- At least 1,000 pixels on the longest side, so shoppers can zoom
- Only the product being sold, with no accessories that aren't included
7. Keep the file
Save the final, error-free file. It becomes the master record of your catalog, and the fastest way to make bulk changes later. Amazon also lets you download your existing listings as a report if you need to rebuild it.
When to get help
If you're listing a few dozen simple products, the steps above are manageable. Bulk uploads get harder with large variation families, multiple marketplaces, or categories that need approval. That's when a catalog specialist usually saves more time than they cost.
We do this work for sellers on Amazon US, UK, Canada, Australia, the EU and the UAE. Request a free audit of up to 3 listings and we'll send a prioritised fix list within 48 hours.
We're an independent agency, not affiliated with Amazon. Amazon updates its listing rules often, so check Seller Central help for the latest requirements in your category.