One box. Two sizes too big. That small difference adds enough cubic volume to push your freight into the next weight bracket. It happens on every single shipment you send.
Most businesses choose their box sizes by habit or by whatever their first supplier happened to stock. But Australian carriers charge by whichever is greater, actual weight or cubic weight, and a box that’s even 50mm too wide in each direction can quietly inflate your shipping bill on every dispatch, week after week, without anyone noticing.
This guide covers standard Australian shipping boxes in millimetres, how to measure your product correctly before you order, what Australia Post’s limits actually mean for your freight costs, and when a made-to-measure box is worth more than stuffing an off-the-shelf size with void fill.
- Standard Australian shipping boxes range from around 200mm to 600mm+ along the longest side
- Always measure L x W x H of your product, then add 50mm to each side if you’re using void fill or bubble wrap
- Australian carriers charge by cubic weight rather than actual weight, so box dimensions directly affect your shipping bill
- The Australian cubic weight formula: L(cm) x W(cm) x H(cm) / 4,000
- Self-locking mailing boxes are the faster, cheaper format for most e-commerce dispatch
- The Boxman stocks standard sizes ready to go in Perth, and custom-manufactures to exact specs with next-day pick-up available
- What Are Standard Australian Shipping Box Sizes?
- How to Measure Your Product for the Right Box
- Standard Shipping Box Sizes by Type
- Australia Post Size Requirements and Flat-Rate Boxes
- How Cubic Weight Works in Australia
- Shipping Box Sizes for Specific Products
- Single Wall vs Double Wall: Does Box Strength Matter?
- When Standard Shipping Box Sizes Don’t Fit Your Product
- Frequently Asked Questions
- Ready to Find Your Right Box Size?
What Are Standard Australian Shipping Box Sizes?
Most online guides to shipping box sizes use inches and reference US carriers like FedEx and USPS. That’s not very useful if you’re shipping with Australia Post, Aramex, or Toll.
In Australia, box dimensions are measured in millimetres (mm), and carrier rules are based on centimetres and kilograms. Here’s how standard sizes group out for Australian shipping:
| Size | Approximate Dimensions (L x W x H mm) | Best For |
|---|---|---|
| Small | 200-350 x 150-250 x 100-200 mm | Books, cosmetics, accessories, small electronics |
| Medium | 350-450 x 250-350 x 150-250 mm | Clothing, kitchenware, small appliances, retail goods |
| Large | 450-550 x 350-450 x 250-350 mm | Homewares, bulk single-item orders, subscription boxes |
| Extra Large | 550mm+ x 400mm+ x 350mm+ | Furniture components, large appliances, multi-unit dispatch |
These groupings aren’t fixed; different suppliers and carriers label their sizes slightly differently. What matters more than the category name is the actual dimension and how it relates to your product, your padding requirements, and your carrier’s cubic weight calculation.
Inside vs outside dimensions: The figures above refer to inside dimensions (the usable space inside the box). When browsing packing boxes online, always compare your product measurements to the inside dimensions, not the external ones. The difference is typically 4-8mm per side for single wall corrugated, and up to 15mm per side for double wall.
How to Measure Your Product for the Right Box
Getting your measurements right before you buy is the step most people rush, and it’s where most sizing mistakes happen.
Measure in L x W x H Order
Length (L) is the longest side. Width (W) is the second-longest. Height (H) is the remaining dimension (how tall the item sits when placed flat). Measure the item as it will sit in the box, and measure to the outermost point on irregular shapes.
Add Your Padding Allowance
If you’re using void fill, bubble wrap, foam corners, or any cushioning: add at least 50mm to each side (100mm total across each dimension). If the item is firm and well-supported with no cushioning needed, size as close to the product as possible.
Match to Inside Dimensions
Your product-plus-padding dimensions should fit comfortably within the box’s inside dimensions. A box that’s slightly too small will bow at the sides and increases damage risk in transit.
If you’re unsure which size fits your product best, visit our FAQs page and our team can help you find the right match.
Standard Shipping Box Sizes by Type
Not all shipping boxes are the same format. Three main types cover most needs, and choosing the right format (not just the right size) makes a real difference to your packing speed, freight cost, and presentation.
Mailing Boxes (Self-Locking Format)
Mailing boxes are a flat-pack format that folds into shape and locks closed without tape. They’re the go-to choice for most e-commerce dispatch: faster to assemble, cleaner presentation, and available in sizes that suit apparel, cosmetics, candles, accessories, and other retail goods.
| Description | Approximate Dimensions (mm) |
|---|---|
| Small mailer | 220 x 160 x 77 mm |
| A5 mailer | 230 x 175 x 100 mm |
| A4 mailer | 310 x 240 x 90 mm |
| Medium mailer | 390 x 280 x 80 mm |
| Large mailer | 430 x 305 x 140 mm |
Mailing boxes aren’t designed for heavy or fragile items. For anything over 5-6kg, or anything that needs significant cushioning, a corrugated carton is the better choice.
Shipping Cartons (RSC Format)
The Regular Slotted Carton (RSC) is the classic corrugated box with flaps on top and bottom, sealed with packing tape. RSC-style shipping boxes are available across the full size range, from small (200mm range) through to extra large (600mm+), in single and double wall corrugated. They’re the right choice for heavier items, anything needing substantial padding, and any shipment where protection matters most.
Packing Boxes
Packing boxes cover a wider range of transit and storage boxes, including cube shapes, flat boxes, hat boxes, and storage boxes. These are useful for moving house or relocating a business, products with unusual proportions, seasonal storage, and high-volume stacking where consistent shape matters. Available in sizes from small through XXL, with single and double wall options.
Australia Post Size Requirements and Flat-Rate Boxes
If you’re shipping through Australia Post, two rules govern what you can send as a standard domestic parcel:
- Longest side: maximum 105cm
- Combined length + girth (length + 2 x width + 2 x height): maximum 140cm
- Maximum weight: 22kg
For most domestic e-commerce, you’ll be well inside these limits. They become relevant when shipping oversized items like furniture components, large equipment, or framed artwork.
Australia Post flat-rate parcel boxes: Australia Post sells five sizes of flat-rate parcel boxes. If your item fits inside one of their boxes and weighs 5kg or under, you pay a flat postage rate regardless of destination, which can produce a meaningful saving for dense items that happen to fit within the box dimensions.
| Australia Post Box | Approximate Dimensions (mm) |
|---|---|
| Small | 140-220 x 150-160 x 10-180 |
| Medium | 240-310 x 190-225 x 102-120 |
| Large | 390-410 x 280-300 x 80-255 |
| Extra Large | 430-500 x 277-440 x 140-350 |
Check the full Australia Post size and weight guidelines for current rates and restrictions, as postage pricing is updated periodically.
How Cubic Weight Works in Australia (and Why Your Box Size Affects Your Bill)
This is the piece most Australian shippers don’t fully understand until they see a freight invoice that doesn’t match what they expected.
Australian carriers, including Australia Post, Aramex, Toll, and StarTrack, charge by whichever is greater: your parcel’s actual weight or its cubic weight. Cubic weight is a measure of how much space your box occupies, expressed in kilograms.
You pay whichever is greater: actual weight or cubic weight
Here’s what that looks like in practice with two different box choices for the same product:
If your product weighs 1.5kg, the oversized box bills you at 6kg, four times the expected freight cost. The tighter box bills at 3.28kg. Same product. Different box. You’ve roughly halved your freight cost on every single shipment.
The 50mm padding rule is a guide, not a minimum. For firm, hard-cased products that don’t need heavy cushioning, sizing closer to product dimensions is the right call. For further reading on how dimensional pricing works across carriers, ShipBob’s dimensional weight explainer covers the broader concept well.
Shipping Box Sizes for Specific Products
The right box size depends on what you’re shipping. Here’s a practical breakdown by product type.
What Size Box Do I Need for Clothing?
Clothing is one of the most forgiving products to pack. It doesn’t need significant cushioning, compresses well, and is generally lightweight. For single garments or small bundles, a self-locking mailing box in the A4 range (around 310 x 240mm) works well for most apparel items. For larger multi-unit clothing orders, a medium corrugated carton in the 350-450mm range is the right call.
The priority with clothing is keeping cubic weight down. A flat, low-profile box almost always beats a tall square box for apparel dispatch.
What Size Box Do I Need for Electronics and Screens?
Electronics need snug sizing plus solid protection. The product should sit firmly in the box with minimal movement, and padding should cover all six faces. For screens and televisions, purpose-built TV boxes with matching internal dimensions are the safest option. An oversized general-purpose box with extra bubble wrap rarely provides equivalent protection and adds unnecessary cubic weight.
For smaller electronics (phones, tablets, accessories), a small to medium box in the 200-350mm range with foam corners or bubble wrap provides good protection without inflating your shipping cost.
What Size Box Do I Need for Fragile Items?
Fragile items such as glassware, ceramics, candles, and bottles need the most generous padding allowance. Use the full 50mm on all sides as a minimum, and consider double wall corrugated for anything over 3kg or anything that cannot absorb any impact at all.
A correctly sized packing box with crumpled paper, foam sheets, or cell dividers is the standard approach. The goal is zero movement inside the sealed box. If you can shake it and feel the item shifting, it needs more fill.
What Size Box Do I Need for Artwork and Flat Items?
Flat items such as prints, framed artwork, posters, mirrors, and canvases need a different approach to sizing. Depth is the critical dimension: the box should be deep enough to hold the item plus rigid edge protection on all corners, but not so deep that the item can slide or flex inside.
Purpose-made art boxes are designed specifically for this use case, with dimensions suited to standard print and frame sizes. For a broader look at packing shallow and flat items, our packaging shallow products guide covers the key considerations.
Single Wall vs Double Wall: Does Box Strength Matter?
Yes, and the difference matters more than most people expect.
Single wall corrugated is three layers: an outer liner, a fluted corrugated medium, and an inner liner. It’s the right choice for most standard shipping applications (products under around 20kg with normal handling), and it’s lighter, which helps keep cubic weight down.
Double wall corrugated is five layers: two corrugated mediums sandwiched between three liners. It provides significantly better stacking strength, crush resistance, and burst strength. It’s the right choice for:
- Products over 20kg
- Items that will be stacked under heavy loads in a warehouse or transit vehicle
- Fragile items requiring maximum protection on all sides
- Long-distance or international shipments with multiple handling points
The flute type also matters. B-flute corrugated (approximately 2.5mm medium thickness) offers better crush resistance from the flat side, making it well suited to shipping cartons that will be stacked. E-flute (around 1.2mm) has a smoother surface that takes print better, which is why it appears more often in retail packaging.
The Boxman stocks both single wall packing boxes and double wall packing boxes across a range of sizes.
When Standard Shipping Box Sizes Don’t Fit Your Product
Off-the-shelf sizes cover most situations, but they don’t cover all of them. If your product is an unusual shape, a long narrow item, or sits between standard sizes, the right answer isn’t to use the next size up and fill it with void fill. That wastes packaging material, adds cubic weight, and increases damage risk. The right answer is a box built to your exact dimensions.
The Boxman has manufactured custom cardboard boxes to measure for Perth businesses since 2002. There are no punishing minimum order requirements, and custom dimensions don’t require expensive tooling charges. Use the live quoting tool to enter your exact dimensions and get a price with a 3D preview in under 60 seconds.
For businesses that need fast turnaround on made-to-measure heavy duty boxes, next-day pick-up is available on orders placed before noon. Our guide to getting a custom box made to order covers the common questions if you’d like to know more before you quote.
Whether you need stock sizes ready to go today or something built to specification, our team is here to help. See the full range on our boxes and packing materials page.
Frequently Asked Questions
What Is the Most Common Shipping Box Size in Australia?
The medium range (approximately 350 x 250 x 150mm to 450 x 350 x 250mm) is the most commonly used for general e-commerce and commercial dispatch. It fits most retail goods with room for padding and stays within efficient cubic weight ranges. For clothing, cosmetics, and small retail items, the A4-range self-locking mailing box (around 310 x 240 x 90mm) is probably more widely used than any RSC carton size.
What Are Australia Post’s Maximum Parcel Dimensions?
The longest side of a standard parcel cannot exceed 105cm. The combined length plus girth (length + 2 x width + 2 x height) cannot exceed 140cm. Maximum weight is 22kg. Anything exceeding these limits needs to be sent as a freight consignment rather than a standard parcel service.
How Much Bigger Should a Shipping Box Be Than the Item Inside?
Add at least 50mm on each side of your product’s dimensions when using void fill or bubble wrap. For snug-fit packing without padding, size the box as close to the product as possible, tight enough that nothing shifts in transit. A significantly oversized box without adequate fill creates more risk of damage, not less.
Does Box Size Affect My Shipping Cost in Australia?
Yes, directly. Australian carriers charge by whichever is greater: actual weight or cubic weight. Cubic weight is calculated as L(cm) x W(cm) x H(cm) / 4,000. A 400 x 300 x 200mm box has a cubic weight of 6kg regardless of what’s inside. If your product weighs 1.5kg, you’re paying for 6kg of freight. Choosing a tighter box that still fits your product and padding reduces that cubic weight and your bill on every shipment.
What Is the Standard Size for a Mailing Box in Australia?
There’s no single standard, but the most common sizes for e-commerce dispatch range from around 220 x 160 x 77mm (small mailer) through to 430 x 305 x 140mm (large mailer). A5 and A4-proportioned mailers are the most common formats for clothing, cosmetics, and small retail goods. They’re available in flat-pack self-locking format that requires no tape, which makes them significantly faster to use at scale.
Can I Get a Custom Shipping Box Size Made in Perth?
Yes. The Boxman manufactures custom cardboard boxes to exact dimensions at its Perth facility, with no minimum order penalty and no expensive tooling charges for custom sizes. Use the live quoting tool at theboxman.com.au to enter your dimensions, choose your style and print options, and get a price in under 60 seconds. For heavy-duty custom boxes needed quickly, next-day pick-up is available on orders placed before noon.
Ready to Find Your Right Box Size?
Choosing the right shipping box size comes down to three things: your product dimensions plus padding allowance, your carrier’s cubic weight rules, and whether a standard size actually fits your product. Get those three right and you’ll ship more reliably, reduce damage claims, and stop paying for freight on dead air.
The Boxman stocks the full range, from self-locking mailing boxes for e-commerce dispatch through to double wall packing boxes for industrial freight, with Australian-made stock available from their Perth facility. If nothing in the standard range fits your product, they manufacture to measure with no minimum order penalty.
For businesses that need fast turnaround on made-to-measure stock, next-day pick-up is available on orders placed before noon.
Get A Boxman Live Quote Today
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Dylan King
General Manager
Dylan is the General Manager at The Boxman, Australia's leading provider of moving and storage boxes. With hands-on experience across every part of the business, Dylan brings practical expertise to help customers find the right packaging solutions — whether they're moving house, storing belongings, or running a business.