If an item has never been listed through FBA, you’ll need to provide dimensions of the item fully packaged when listing. It’s very easy to do this while listing!
First, list your product as normal. When you click 'Add to Batch', a pop up will appear for any items that require package dimensions, allowing you to enter in the Weight, Length, Width, and Height.
Once you press OK, you'll get a success message, and your item will be added to your batch.
You will now notice an 'Update Package Dimensions Pending' message within your MSKU data, where you have the option to check the status.
After about 15 minutes, you will want to check if the dimensions have been accepted by Amazon. Click that 'Check Status' button, and once the dimensions have been accepted, the message and button will disappear. Your item will be effectively added to the batch.
Note: You will not be able to Review or Complete your batch until all dimensions have been accepted. If it is taking a long time for your items to be accepted, follow the steps in the Missing Dimensions solutions article to add the dimensions in Seller Central. Wait a few moments after you have added the dimensions, and click the 'Check Status' button again. You will also be able to delete the item from the batch if needed.