You’ve designed the artwork, picked the size, and now you’re trying to work out what “350gsm single wall” actually means for your product, and whether kraft or white is the right call before you commit to a print run.

This guide comes from the team at Wabs Print, a London-based packaging supplier that has produced custom boxes for UK businesses since 2008. We supply 8,500 plus brands, and mailer box specification is one of the most common quote-stage questions we get, mostly because the difference matters more than people expect once a box has actually been through a courier network. Wabs Print, based in London, supplies custom mailer boxes to e-commerce businesses across the UK, from independent sellers in Birmingham and Leeds to growing online brands in Sheffield and London. By the end of this guide you will know exactly what our standard mailer box is built from, how that compares to heavier corrugated options if you need them, and what it costs. If you want a price now, custom mailer boxes UK will get you a quote within 24 hours, no minimum order required.

What Are Wabs Print Mailer Boxes?

Our standard mailer box is a white, 350gsm, single wall corrugated box with self-locking tabs that close without tape, available in three stock sizes, small at 220mm x 160mm x 50mm, medium at 305mm x 220mm x 80mm, and large at 350mm x 250mm x 100mm, plus custom dimensions up to 500mm x 400mm x 150mm. It holds up to 5kg, ships flat-packed, and is 100 percent recyclable through standard UK kerbside collection.

The self-locking tab is worth understanding before anything else, since it changes how the box behaves at the packing bench more than any material choice does. Tabs fold into slots cut directly into the board, so there is no tape gun, no dispenser, and no risk of a half-sealed box opening in transit from a tape edge lifting. For a small operation packing fifty orders a day by hand, that assembly speed adds up.

One thing most first-time buyers do not realise: white and kraft are genuinely different product lines here, not a tick-box on the same form. Our flagship mailer box is white card, chosen because it gives a cleaner base for full colour branding and a more premium unboxing moment than a kraft surface does. If a natural, recycled look matters more to your brand than colour accuracy, our kraft boxes range covers that separately, built on a different base material rather than being a simple liner swap on the same mailer box.

The three stock sizes exist because most products fall into one of three rough size brackets, and ordering against a stock size rather than a custom dimension usually means faster turnaround at the lower end of the pricing range, since there is no new die line to cut. Custom sizing earns its place when your product does not fit any stock option without excessive void space, since a box that is meaningfully larger than it needs to be both costs more to ship and lets your product shift around in transit. If you are between two stock sizes, it is worth requesting a custom quote rather than rounding up to the next stock option by default.

Corrugated Flute Profiles Explained: E-flute vs B-flute

Beyond our standard single wall spec, it helps to understand what the flute terminology you’ll see across the packaging industry actually means, particularly if you are comparing quotes from different suppliers or considering a custom upgrade for a heavier product.

E-flute is the most common profile across the industry for exactly the reason our own standard spec favours a flatter, print-friendly single wall construction: it strikes the best balance between protection and printability at typical parcel weights. B-flute earns its place when a product is genuinely heavier or more breakable than a standard 5kg parcel, where the extra cushioning matters more than print sharpness. If your product regularly tests the upper end of our 5kg weight capacity, that is worth flagging at quote stage so we can talk through whether a heavier custom spec makes sense for you specifically.

When to Upgrade Beyond the Standard Spec

Crush resistance is the property most people actually care about without knowing its name, the board’s ability to keep its shape under the weight of other parcels stacked on top of it in transit. Our standard single wall white box handles typical e-commerce weights comfortably up to its 5kg capacity. Beyond that, or for genuinely fragile items like glassware or ceramics, a heavier custom spec closer to B-flute territory protects better than pushing a standard box to its limit.

Hartwell & Finch, an online ceramics and homeware seller shipping from a unit in Bristol, came to us after a run of breakages using a generic supplier’s standard mailer box for their heavier stoneware mugs, items sitting right at the edge of what a typical single wall box should carry. We moved their stoneware range onto a custom heavier spec closer to B-flute thickness, while keeping their lighter homeware accessories on our standard white mailer box to control cost. Their breakage rate on the stoneware range dropped from roughly 4 percent to under 0.5 percent over the following quarter, and because only the heavier SKUs moved to the upgraded spec, their average packaging cost per order rose by only 6 percent overall rather than across their full catalogue.

Cost and Pricing Guide

These figures are for our standard white mailer box, the structure we quote most often. A custom heavier spec, closer to B-flute, typically adds a moderate premium over these figures, and we will confirm the exact adjustment at quote stage once we know your product’s weight and dimensions.

Standard White Mailer Box Pricing by Volume

Custom Heavier Spec, Closer to B-flute, Pricing by Volume

Standard delivery is free to any UK address, England, Scotland, Wales, and Northern Ireland, on every order regardless of size. We will be straight about why minimum orders exist at all elsewhere in the industry: a print run carries the same setup cost whether you order 10 boxes or 10,000. We have built our pricing to absorb that cost at low volumes, which is why a small order is genuinely possible, though most e-commerce brands start somewhere between 250 and 500 units once they know their packed product fits the box correctly. For a deeper look at how mailer boxes compare against rigid construction altogether, our rigid boxes vs mailer boxes guide covers that separate decision, where rigid boxes typically run from £2.50 to £17.00 per unit depending on volume and finish, well above mailer box pricing, which is the trade-off for the weightier, more premium feel rigid construction gives a product over £40 retail. Our ultimate custom packaging guide is where the standard spec figures above come from if you want the fuller pricing picture across other box types.

How to Choose: A Decision Framework for Your Product

Work through these in order rather than choosing a spec first and working backward from there.

1. Weigh your packed product, not just the item itself. Under our standard 5kg capacity, the white single wall box handles most products without issue. At or above that limit, particularly with anything breakable, talk to us about a custom heavier spec.
2. Decide if kraft or white serves your brand better. This is a positioning decision, not a protection one, and the two sit on different product lines here rather than being a tick-box on the same order. White suits bold, colourful, or photography-led branding. Kraft, via our separate kraft boxes range, suits natural, eco-led, or minimalist branding.
3. Check whether a stock size fits, or if you need custom dimensions. Our three stock sizes cover most standard products. If yours does not fit comfortably with minimal void space, our custom box dimensions guide walks through how to specify a custom size correctly.
4. Consider whether your product is better suited to a rigid box altogether. If you are shipping a premium product retailing above roughly £40, the weightier feel of a rigid box, at a higher per-unit cost than any mailer box spec, sometimes earns back its cost through perceived value in a way that no mailer box upgrade can replicate.

If mailer boxes are one part of a wider e-commerce packaging strategy, our e-commerce packaging hub covers how mailer box choices fit alongside void fill, tape, and inserts.

Mailer Box Materials UK: Delivery Across the Country

Wherever your e-commerce business is based, the lead time, pricing, and free UK shipping policy stay the same. A seller fulfilling orders from a unit in Leeds works to the same 7 to 10 working day turnaround from artwork approval as a larger operation in Sheffield, and delivery is free to any UK address regardless of order size or location.

We get a steady run of enquiries from online sellers in Birmingham asking specifically whether our self-locking tabs hold up as well as taped boxes for international parcels, not just UK shipments. For UK delivery they perform at least as well, since the tab folds into a slot rather than relying on adhesive that can lift with temperature change. Whether you are packing orders from a spare room in London or a small warehouse in Birmingham, turnaround and pricing are identical, and there is no minimum order regardless of where in the UK you are based.

Compliance and Sustainability for Mailer Box Materials

Our standard white mailer box is 100 percent recyclable through normal UK kerbside card and paper collection, and the board is FSC certified, which matters if your brand makes sustainability claims about responsibly sourced material, since your packaging can carry the FSC mark on request. Under OPRL guidance, a clear recycling label should sit on a front-facing panel, visible before the box is opened, which we can include in your design layout at no extra cost.

Many of the material sourcing principles covered in our sustainable food packaging guide apply just as directly here even though mailer boxes are not food packaging: recycled content, FSC sourcing, and choosing single-material construction that recycles cleanly without separating components. This reflects packaging compliance guidance as of June 2026. Always verify current requirements at gov.uk before making compliance decisions for your business.

FAQ

What is a Wabs Print mailer box made from?

Our standard mailer box is 350gsm white card stock, single wall corrugated, with self-locking tabs that close without tape. It comes in three stock sizes, plus custom dimensions up to 500mm x 400mm x 150mm, and holds up to 5kg. Kraft is available as a separate product line built on a different base material, not as a finish option on this specific box.

What is the difference between E-flute and B-flute corrugated board?

E-flute is a thinner profile, around 1.5mm, offering a flatter surface for clean printing and good protection for typical e-commerce weights. B-flute is thicker, around 3mm, with more cushioning for heavier or fragile items, but a coarser surface that shows slightly less fine print detail. Our standard mailer box uses a single wall construction comparable to E-flute performance for most products.

My product is heavier than usual, can I still use a mailer box?

Up to 5kg, our standard white mailer box handles most products without issue. Above that, or for genuinely fragile items, talk to us about a custom heavier spec closer to B-flute thickness rather than pushing the standard box past its limit. A homeware seller we worked with cut breakages from roughly 4 percent to under 0.5 percent by moving only their heaviest SKUs onto an upgraded spec.

Do you deliver custom mailer boxes to Leeds and Sheffield?

Yes. Wabs Print delivers custom mailer boxes to businesses across the UK, including Leeds, Sheffield, London, Manchester, Birmingham, and Bristol, with free UK shipping on every order regardless of size. Express turnaround options are available at checkout if you need your order faster than the standard 7 to 10 working days.

What is the minimum order for custom mailer boxes?

There is no minimum order. You can order a single box or several thousand and receive the same print quality either way. Most e-commerce brands start somewhere between 250 and 500 units once they have confirmed the box size fits their packed product correctly, then reorder at higher volumes once demand is proven.

How long does it take to get custom mailer boxes printed?

Standard turnaround is 7 to 10 working days from approved artwork. If you need it faster, tell us at the quote stage rather than after artwork approval, since express options are far easier to arrange before production scheduling begins. Delivery is then free to any UK address.

Should I choose a mailer box or a rigid box for my product?

Mailer boxes suit most e-commerce shipping up to 5kg at a lower per-unit cost, typically under £1 at volume. Rigid boxes cost considerably more, typically £2.50 to £17.00 per unit depending on volume and finish, but the weightier feel often earns that back in perceived value for products retailing above roughly £40, particularly for gifting occasions.

Making the Call

Mailer box decisions start with what Wabs Print actually builds as standard, a white 350gsm single wall box with self-locking tabs, not an open menu of flute and liner combinations. Know your product’s weight against the 5kg capacity, decide if white or our separate kraft range fits your brand better, and only look at a custom heavier spec if your product genuinely needs it.

Whether you are shipping from a spare room in London, a unit in Birmingham, or a small warehouse in Bristol, Wabs Print delivers custom mailer boxes across the UK with no minimum order, free UK shipping, and the same 7 to 10 working day turnaround regardless of volume. If you are ready to get a price, custom mailer boxes UK and you will have a quote within 24 hours.