What this guide is for
Understand the difference between an equal split and a weight-proportional split, and when missing weights should stop you.
The problem being solved
International shipping is usually billed per parcel, not per item. If a parcel holds six items, the shipping charge is one number but six items caused it. Allocation is simply the rule you choose for sharing that one number fairly.
There is no universal 'correct' rule. The honest move is to pick a rule, state it, and apply it consistently.
Equal per item
- 1
When it fits
Choose equal split when the items are similar in size and weight, or when you simply want a fast, defensible split. Each item line receives the same share of the parcel's international shipping.
- 2
What it ignores
Equal split ignores weight entirely, so a heavy item and a light item get identical shipping. That can understate the heavy item and overstate the light one.
Proportional by actual weight
- 1
Keep working weights per item
Give every item line in that parcel a quantity and a unit weight in grams. The workbook multiplies them to get each item's total weight.
- 2
Let the workbook do the ratio
Each item receives its own weight divided by the parcel's total weight, multiplied by the shared shipping figure. Heavier items carry more of the bill — usually closer to reality for mixed parcels.
- 3
Respect the block
If any item in the parcel has no weight, the proportional method is blocked and the tool says so. Fix the weights, or switch to the equal method — do not let the tool quietly invent a weight.
Unknown weight blocks proportional calculation by design. A blocked split is a prompt to go weigh the item, not a bug.
Recording which method you used
Because the two methods give different per-item results, write the method into your notes so a future you (or anyone reading your sheet) knows how the parcel was split. The exported CSV shows the allocated international shipping per line, which makes the method auditable.