Ounces to Kilograms

Putting an Ounce Reading in the Kilogram Box on a Customs Form

A parcel headed abroad gets weighed on a kitchen or postal scale that answers in ounces, and then meets a green CN22 sticker or a full CN23 declaration whose weight field is labelled in kilograms. The form does not offer a second unit and the number has to be right, because it travels with the item through two postal systems and a customs authority that never sees your scale.

Conversion factor: 1 oz = 0.028349523125 kg exactly, so multiply the ounce reading by 0.02835. A packed 13 oz padded envelope is 0.369 kg — the figure to write in the weight box, not the 13 that came off the scale.

What the Weight Field Is Actually For

A shared international language

Postal declarations follow Universal Postal Union templates used by every member country, and those templates are metric so a form written in one country can be read in any other.

Which form the weight decides

The kilogram figure is part of what determines whether a short CN22 sticker will do or a longer CN23 declaration is needed, so getting it wrong can mean the wrong paperwork entirely.

Cross-checked on arrival

Destination handlers reweigh items and compare against the declaration. A figure that is plainly off invites inspection and delay even when the contents are entirely ordinary.

The same number downstream

Whatever you declare is what appears in the electronic advance data sent ahead of the item, so the label, the online manifest and the sticker should all carry one consistent value.

Filling In the Weight Line Before You Seal the Parcel

Weigh the item finished — taped, labelled, ready to post — because packaging is part of what the carrier will put on its own scale.

Enter the ounce reading from your scale

Type the figure in the left field — 13, 27.4, 62. The kilogram value appears as you type, so there is no arithmetic to do by hand while holding a roll of tape.

Round to what the form will hold

Most declaration boxes accept two or three decimals. Round up rather than down so the declared weight is never less than the real one, and never below 0.001 kg for a very light item.

Copy the value into the online form

The copy button gives the plain number with no unit and no spaces, which is what a postal portal's weight field expects. Ctrl + C inside a field does the same if you would rather stay on the keyboard.

Check a metric limit in ounces

Press the swap button (↔) for kg → oz when a service description quotes a metric ceiling: a 2 kg small-packet limit is 70.5 oz, which is easier to compare with what your scale is showing.

General guidance only: weight limits, form thresholds and documentation rules differ by postal operator, service and destination, and they change. Confirm the requirements for your own service and country before posting — this page converts the number, it does not tell you which service or paperwork applies.

Declaration Weights at the Steps That Matter

The ounce readings that come up repeatedly on outbound international mail, with the kilogram value to three decimals and the same figure rounded upward for a form that offers only two places.

Scale reading	Kilograms (3 dp)	Rounded up (2 dp)	Where it turns up
1 oz	0.028 kg	0.03 kg	A single-sheet letter — the lightest step any scale usefully resolves
4 oz	0.113 kg	0.12 kg	A thin flat or a small documents envelope
8 oz	0.227 kg	0.23 kg	Half a pound — a common price break on light parcel services
13 oz	0.369 kg	0.37 kg	A long-standing US ceiling for stamped mail before counter handover
16 oz	0.454 kg	0.46 kg	Exactly one pound, and the first whole-pound rate step
32 oz	0.907 kg	0.91 kg	Two pounds — still under the small-packet ceiling with room to spare
70.5 oz	1.999 kg	2.00 kg	A hair under 2 kg, the classic small-packet cut-off

The last row is the one to remember while packing. Because 2 kg lands at 70.55 oz, anything from about 70.6 oz upward has crossed the ceiling — a margin of well under an ounce, which a bubble mailer and a strip of tape can swallow on their own.

Useful While the Paperwork Is Open

One parcel after another

Both boxes take typing, so a batch of outbound items can be converted in sequence while you work down the pile, without clearing the page between them.

Metric ceilings read in ounces

Swapping the direction answers the other question — how many ounces a kilogram threshold allows — which is what you need when the scale has no metric mode.

Grams for the very light items

All eighteen weight units sit in searchable dropdowns on both sides, so a documents envelope is easier to read in grams than as a string of leading zeros in kilograms.

A value the form will accept

Copy delivers the number with no unit attached, so nothing has to be deleted before a customs portal or shipping label field takes the entry.

Questions About the Weight Line on a Declaration

Why do postal customs forms insist on kilograms?

Because the form is an international document, not a domestic one. CN22 and CN23 come from Universal Postal Union templates that every member postal operator uses, and the weight field is defined in kilograms so an item posted in one country can be processed in another without anyone converting anything. The same logic applies to the electronic data sent ahead of the parcel: metric everywhere means no ambiguity at the border.

Should I declare gross weight or net weight?

The parcel's total weight box is gross — everything the carrier lifts, so contents plus box, padding, tape and label. A CN23 additionally asks for a net weight per line item, meaning the goods alone without the packaging around them. A 13 oz shipment made up of two 4 oz items in a 5 oz mailer is 0.369 kg gross with net figures of 0.113 kg each. If a form gives you only one weight field, it wants the gross figure.

What happens when a parcel goes over 2 kg?

Two kilograms — 70.55 oz — is the traditional small-packet ceiling in the postal system, and crossing it moves the item into a parcel category with different paperwork: typically a full CN23 rather than the short CN22 sticker, and a different service and rate table. It is worth weighing before you commit to packaging, because at 68 or 69 oz the choice of mailer alone can decide which side of the line you land on. Individual operators set their own limits above that, so check the service you intend to use.

How should I round when the form only takes two decimals?

Round up, so the declared weight is never lower than the real one. Two decimals give you 10 g steps: 13 oz is 0.36854 kg, which becomes 0.37 kg rather than 0.36. Under-declaring is the error worth avoiding, since the receiving side reweighs and a figure below the actual weight looks like an attempt to duck a threshold. Rounding a fraction of a gram upward costs nothing and keeps the declaration defensible.

How do I state the weight when one parcel holds several different items?

List each type of item on its own line with its own quantity, net weight and value, then give the parcel's total gross weight in the summary box. Weigh the items separately before packing rather than guessing afterwards — a scale that reads in ounces makes this easy, since 4 oz and 9 oz convert cleanly to 0.113 kg and 0.255 kg. The individual net weights will add up to less than the gross figure, and that difference is simply the packaging.