Thank you for reaching out to the Shopify Community Forums (and welcome!) with your question about your shipping rates. I understand that your shipping rates are not calculating properly at the checkout.
From the PDF documents you attached, I can see that your rates are based on total order weight and that this order is being bumped to the higher rate. This means that something with this order is adding additional weight.
Without being able to see your current shipping settings, I can assume that the additional weight is coming from your DEFAULT PACKAGE settings. The shipping rates are calculated using the default package weight + the item weight to accurately calculate shipping at the checkout. If you do not want the package weight to affect the shipping rates, you can edit it under Settings > Shipping to have 0 weight. This will not affect your ability to buy your shipping labels after the order is placed.
Please let me know if that was the issue!
Shay | Social Care @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog
Hi, By analyzing the pdf file you have shared, shipping costs are calculated based on the total weight of the items in the cart. Can you accurately calculate the weights of all the 3 items separately and add the weight values, if the weight range falls between 1.51lb-2lb, the calculated shipping price of $16.96 is correct. If the total weight value is less than 1.51lb, the extra weight is added from the settings you had set up. Can you tell me what exact settings you have made in shipping?