Capacity, resolution and platform size, and why guessing a package weight costs money on every label.
Short answer
Choose a scale whose maximum capacity comfortably covers your heaviest package and that still reads in single ounces for light ones. Carriers price by weight and round upward, so an estimate costs you on every label, and an underpaid package can come back.
A scale that reads to a tenth of an ounce is useful for small parcels; one that tops out low is useless the day you ship something heavy. Look at both numbers and size for your heaviest realistic package, not the average one.
Platform and display
A package wider than the platform is fine if it balances, but it will hide the display
A remote or pull-out display, or a hold function, solves that
A flat platform is easier to wipe down than a bowl
Check it sits level and does not rock
Power
Batteries are fine for occasional use. If you weigh dozens of packages at a time, an AC adapter is worth having, and not every scale includes one.
Weigh it the same way every time
Weigh the package fully sealed, labels and all
Let the reading settle before you write it down
Round up when you buy postage, never down
Keep the scale away from drafts and off a flexing shelf
Common questions
Can I use a kitchen scale?
For very light packages, sometimes. Most kitchen scales have too little capacity and too small a platform for a parcel.
Does dimensional weight matter?
For larger or lighter-than-they-look boxes, carriers may price on size rather than weight. A scale answers weight; you still measure the box.
How accurate does it need to be?
Accurate enough that you are on the right side of the carrier's next price step. For small parcels that usually means single ounces.
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