What's the cheapest way to send a large letter using Australia Post? (Updated April 2024)

johna by | April 6, 2024 | Reviews


For letters and documents less than 250g, it's cheapest to send in your own envelope ($3.00 up to 125g, $4.50 up to 250g).

For letters and documents over 250g and under 500g, if they fit in a C4 envelope then it's cheapest to send in a prepaid C4 envelope for $6.50.

If you need a larger B4 envelope then you can use your own envelope and send for $7.50 or use a pre-paid B4 envelope for $7.80.

If you need tracking then consider using a $8.35 prepaid C4 envelope with tracking or an $8.80 Registered Post B4 prepaid envelope.

Express post is the quickest option and costs $10.50 for a prepaid B4 envelope.

Regular letters

Australia Post define a large letter as up to 360 x 260mm in size and a maximum of 20mm thick. The weight limit for letter rates is 500g.

If you use your own envelope, you will pay based on weight:

Up to 125g - $3.00
Up to 250g - $4.50
Up to 500g - $7.50

However, in some cases it may actually be cheaper to use one of Australia Post's prepaid envelopes.

These come in a couple of different sizes, but there is no weight scale, just a weight limit if 500g.

C4 (329 x 229mm) - $6.50
B4 (353 x 250mm) - $7.80

So, if you are sending over 250g and it will fit in a C4 envelope, it's actually cheaper to buy a prepaid envelope ($6.50 including an envelope versus $7.50 and supplying your own envelope).

Prepaid C4 envelope Prepaid B4 envelope

Source: https://auspost.com.au/sending/send-within-australia/compare-letter-services/regular-letters-cards and https://auspost.com.au/business/shipping/satchels-and-packaging/prepaid-satchels-and-envelopes

Domestic letter with tracking

If you need tracking, Australia Post offer a prepaid C4 envelope (329 x 229mm) that includes tracking and proof of delivery for $8.35. These have the advantage of being a sturdy cardboard instead of paper so will better protect the contents and are unlikely to be folded. Being cardboard, though, they are heavier (about 70g) and will use up some of the 500g weight limit.

Prepaid C4 with tracking

Source: https://auspost.com.au/sending/send-within-australia/compare-letter-services/letter-tracking

Registered Post letters

If you need tracking for something larger than will fit in a C4 envelope, or if you need a signature on delivery, then there is a B4 size (353 x 250mm) Registered Post envelope available for $8.80. These also have a 500g weight limit.

Registered Post B4 envelope

Source: https://auspost.com.au/sending/send-within-australia/compare-letter-services/registered-post-letters

Express Post

Express Post for large letters is available in one size only – B4 – which costs $10.50.

Express post includes tracking and delivery is next business day to major cities, although this is no longer guaranteed.

Source: https://auspost.com.au/sending/send-within-australia/compare-letter-services/express-post-letters

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