Stop guessing shipping costs: weigh every package
Carriers price by weight and size. Guess low and you may get an adjustment charge later; guess high and you overpay on every label.
Use a postal scale
A digital postal scale such as the DYMO M10 gives you the real weight before you buy postage.
Save weights in Shopify
Enter each product's shipped weight (including packaging) in Shopify. Calculated shipping rates at checkout then match what you pay the carrier much more closely.
Weigh the box, not just the product
Boxes, mailers and padding add weight. Weigh a packed order once for each box size and note the difference.