Measure First, Order Once: Matwell Frame Sizes and Solid Brass Options

Most matwell frames come pre-cut in three inside-opening sizes: small at 0.61m × 0.36m (24″×14″), medium at 0.69m × 0.41m (27″×16″), and large at 0.76m × 0.46m (30″×18″). Matwell size always refers to the inside opening, the mat well itself, not the outer frame width. Before ordering anything, measure your recess to the nearest millimetre and note the depth.

TL;DR:

Precise inside dimensions and multiple depth measurements are essential to ensure a matwell frame fits flush and prevents tripping hazards.

Standard matwell sizes have an inside opening of up to 0.76m by 0.46m with profile depths of 12mm, 17mm, or 25mm, depending on mat thickness and usage.

Choosing the correct profile depth is critical, as a too-shallow frame leaves the mat proud, while a too-deep frame risks door clearance issues.

For irregular or non-rectangular recesses, ordering a custom cut-to-size frame or using a template reduces installation errors.

High-quality solid brass frames with durable finishes outperform cheaper alternatives by resisting damage and wear over years of foot traffic.

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What are the standard matwell frame sizes?
How do you measure a matwell for a new frame?
Measuring a curved or irregular matwell
Choosing frame depth for your mat thickness
What to tell your supplier when ordering
On-site tolerances and installation checks
Why hand-finished solid metal frames outperform the alternatives
Do matwell frames work with every floor type?
Materials and finishes: what actually affects durability
What drives the price of a matwell frame?
Get the measurement right before you worry about anything else
Order the right size the first time
Manufacturer datasheets and installation guides
Sources
FAQ

What are the standard matwell frame sizes?

The three pre-drilled sizes listed on most retail product pages cover the majority of UK residential and light commercial doorways, but the profile depth you choose matters just as much as the inside dimensions. A frame that fits the opening but sits too shallow will leave your mat proud of the floor; too deep, and the mat rattles or the door catches on it.

Suppliers typically quote profile depths of 12mm, 17mm and 25mm. The 12mm option suits thin entrance mats and low-pile carpet tiles. The 17mm depth is the most common, built around standard coir and contract matting, and matches the UMFA18 profile code used across manufacturer datasheets. The 25mm depth handles deep coir matting with heavy rubber or PVC backing, the kind you find in busy commercial lobbies.

Size	Inside opening (metric)	Inside opening (imperial)	Typical profile depth	Suits
Small	0.61m × 0.36m	24″ × 14″	12mm–17mm	Thin mats, domestic side doors
Medium	0.69m × 0.41m	27″ × 16″	17mm	Standard coir/contract mats, most front doors
Large	0.76m × 0.46m	30″ × 18″	17mm–25mm	Deep-pile or heavy-backed mats, commercial entrances

If your recess doesn’t match any of these, don’t force it. Most suppliers also sell continuous extrusions, usually in 4,000mm lengths, that get mitred to fit a bespoke recess exactly. That’s the route for anything outside the standard three, and it’s also where solid brass frames earn their keep, since they can be cut and mitred on site without cracking the way cheaper stock does.

How do you measure a matwell for a new frame?

Get this wrong and you’ll either order a frame that won’t sit flush or one that leaves a gap wide enough to trip on. Work through it in this order:

Measure the inside length and width of the recess to the nearest millimetre, not the nearest centimetre. Small errors compound once you add clearance.
Record the smaller of the two horizontal measurements as the width if the opening isn’t perfectly square. This avoids confusion later when you’re relaying figures to a supplier.
Check the recess depth at several points, not just one corner. Old subfloors and screed rarely sit perfectly level, and a single measurement can hide a lean that causes the mat to rock.
Check door clearance and skirting details around the opening, including any threshold strip or floor transition that meets the recess.
Allow a clearance gap of around 3–4mm on all sides of the mat, a tolerance recommended in installation guidance for entrance matting to stop the mat binding as it expands or as foot traffic shifts it.
Decide whether you need pre-drilled holes or mitred corners before you contact a supplier, since this changes lead time and price.

Measuring a curved or irregular matwell

Not every recess is a clean rectangle. Older buildings, curved thresholds and awkward porch conversions throw up wells that don’t have four square corners, and measuring these badly is the single biggest cause of a frame that won’t seat properly.

Start by establishing a genuine 90° reference. A large builder’s square or a straightedge held against two adjacent sides will show you immediately whether a corner is true or not. Where the opening curves or tapers, take several cross-section measurements rather than one, noting the maximum and minimum widths and any radius on curved sections. Installation guidance on measuring non-rectangular matwells recommends this multi-point approach specifically because a single width figure hides too much variation to cut accurately.

If the shape is genuinely awkward, order a cut-to-size mat rather than trying to force a standard rectangle into it, or supply a paper or fibreboard template cut to the exact recess. A template removes almost all the guesswork and is worth the ten minutes it takes to make.

Choosing frame depth for your mat thickness

Depth compatibility trips up more buyers than size does, mostly because it’s the dimension nobody thinks to check until the door won’t close properly.

12mm profiles suit low-profile mats and thin carpet tiles, common in domestic side entrances with limited recess depth.
17mm profiles are the standard fit for coir and contract matting, and the depth most manufacturer datasheets, including the UMFA range, build around as the default.
25mm profiles handle deep or heavily backed coir matting, typically seen in commercial lobbies with higher footfall.

The outer border width of the frame also affects how much you need to cut out of the surrounding floor, since a wider border eats into the finished opening even though the inside dimension stays the same.

Pro Tip: Always check door swing clearance before ordering a deeper profile. A 25mm frame with a thick mat can lift the finished floor height enough to catch the bottom of the door, especially on older doors that were hung tight to begin with.

What to tell your supplier when ordering

Get the specification wrong at the ordering stage and you’ll be waiting for a second delivery. Have these details ready before you call or order online:

Inside opening width and length, measured to the nearest millimetre.
Required profile depth (12mm, 17mm or 25mm) based on your mat thickness.
Frame border width, since this determines how much extra floor area the frame occupies.
Finish required, along with whether you need a mitred assembled frame or continuous extrusions for on-site cutting.
Whether you need pre-drilled fixing holes, and if corner brackets or factory mitring are required.

Standard extrusions are commonly supplied in 4,000mm lengths for on-site mitring, which gives fitters flexibility on awkward recesses. Cut-to-size and bespoke finishes generally take longer to dispatch than pre-cut standard sizes, so factor in lead time if you’re working to a fitting date. It’s also worth asking whether the supplier charges separately for mitring, since per-metre pricing doesn’t always include that labour.

On-site tolerances and installation checks

A frame that measures correctly on paper can still fail on site if these checks get skipped:

Keep the 3–4mm clearance around the mat consistent on all sides, adjusting recess depth so the mat backing sits flush rather than proud.
Check for door binding once the frame and mat are in place, and confirm the floor either side of the recess is level.
Line up pre-drilled holes with genuine fixing points in the substrate before committing to screws.
If the recess is shallower than expected, pack it rather than forcing a deeper profile; if it’s too deep, ask about plate trims to make up the difference.

Why hand-finished solid metal frames outperform the alternatives

Qualitycarpettrims specialises in flooring trims, door bars, thresholds and edge trims built to connect carpet, laminate, vinyl and hard flooring cleanly. Every matwell frame is solid brass, hand-finished, and available in ten finishes, which matters more than it sounds once you’ve seen what happens to cheaper stock. Wooden, plastic, rubber and aluminium trims tend to split, bend or dent under repeated foot traffic and door swing, whereas solid brass trims generally resist such damage.

Selecting the correct profile depth and getting compatibility right the first time saves a return trip, which is why fitting guidance and honest sizing information matter as much as the product itself. Getting that detail right the first time is worth more than any warranty small print.

Do matwell frames work with every floor type?

A matwell frame’s compatibility depends less on the flooring either side of it and more on the recess construction underneath. Timber subfloors, concrete screed and older suspended floors all take a matwell frame differently, mainly because the fixing method and achievable depth vary.

On concrete or screed floors, frames are typically fixed with adhesive or masonry screws directly into the substrate, and the recess depth is usually fixed at build stage, which limits your profile choice to whatever depth the recess already offers. On timber subfloors, there’s often more flexibility to adjust recess depth slightly by packing or trimming, which opens up the 25mm profile option even in older properties.

Commercial environments add another layer: heavy footfall entrances in offices, retail units or public buildings usually call for the deeper 25mm profile paired with contract-grade matting, since thinner setups wear out fast under constant traffic. Domestic hallways rarely need that much depth, and a 17mm frame handles the job comfortably.

The one constant across every floor type is the fixing frame itself. Solid brass doesn’t corrode against damp screed or react with adhesives the way some coated alternatives can, which is part of why it’s specified so often in both refurbishment and new-build entrance work, regardless of what sits either side of the frame.

Materials and finishes: what actually affects durability

The finish on a matwell frame isn’t just decorative. It determines how the frame handles years of foot traffic, moisture from wet shoes, and the constant flex of a door swinging over it.

Wooden trims swell, warp and eventually split when they take on moisture from a wet doorway, which is exactly where a matwell frame lives. Plastic and rubber trims degrade under UV exposure near glazed doors and lose their shape under sustained pressure. Aluminium trims dent easily and show scuffing quickly in high-traffic commercial settings. None of these hold up to the punishment a front entrance delivers day after day.

Solid brass, powder coated in a durable finish, resists all three failure modes: it won’t split like timber, won’t degrade like plastic, and won’t dent like aluminium under normal use. Qualitycarpettrims offers ten distinct powder-coated finishes, giving fitters and homeowners a genuine match for existing ironmongery, from warm brass tones through to contemporary matt finishes, without compromising the underlying metal’s resistance to splitting, bending or denting.

Aesthetically, the finish choice matters most where the matwell frame sits in clear view, typically a front entrance hallway rather than a back door utility space. A finish that matches door handles, hinges and other brassware pulls the whole entrance together, while a mismatched trim stands out for the wrong reasons. Because the frame is solid metal rather than a thin coated shell, the finish also wears evenly over years of use instead of flaking to reveal a different colour underneath, which is the tell-tale failure point of cheaper plated trims.

What drives the price of a matwell frame?

Three factors move the price of a matwell frame more than anything else: size, customisation, and material.

Standard pre-cut sizes cost less than bespoke dimensions simply because they’re stocked and don’t require individual cutting or mitring on order. Once you move to a custom inside opening, whether that’s a non-standard rectangle or an irregular shape requiring a template, you’re paying for the labour of cutting and finishing to your exact measurements rather than picking from stock.

Customisation goes beyond size. Pre-drilled holes, factory mitred corners versus continuous extrusions for site cutting, and finish choice all add to the specification, and each one can shift the price. A factory-mitred frame in a premium finish will always cost more than a standard extrusion in a basic finish, because more of the fabrication work happens before it reaches you.

Material is the biggest long-term factor, even if it isn’t always the biggest line on the invoice. Cheaper trims made from aluminium, plastic or timber look competitive on price initially, but they need replacing far sooner, so the real cost over the life of the entrance is higher, not lower. Retail pricing commonly sits within a per-metre bracket that varies by material and finish, and it’s always worth checking whether mitring or cut-to-size work is charged separately before comparing quotes.

Get the measurement right before you worry about anything else

Most of the advice circulating on matwell frames focuses on finish and style, which is understandable but backwards. None of that matters if the inside opening is wrong by even five millimetres, because a frame that doesn’t sit flush will show every day, in every piece of foot traffic that catches its edge.

The conventional advice to “measure twice” undersells what’s actually needed here. You need multiple depth readings, a genuine square reference for corner-checking, and an honest clearance allowance, not a single tape-measure reading taken once and trusted. That’s where most DIY orders go wrong, and it’s rarely the supplier’s fault when a bespoke frame doesn’t fit.

If there’s one thing worth prioritising above finish, above price, above everything else in this guide, it’s getting the depth measurement right at multiple points in the recess. A frame that’s a millimetre out on width can often be packed or trimmed on site. A profile that’s the wrong depth for your mat thickness cannot be fixed without buying again.

— Matt

Order the right size the first time

Getting a matwell frame size wrong after cutting into a floor is an expensive mistake. Some suppliers offer solid brass, hand-finished frames in multiple finishes, available as bespoke cut-to-size or standard pre-drilled options, so there’s often a specification that fits your recess rather than the other way round.

Send your measured inside opening (width, length and depth at several points) and Qualitycarpettrims will confirm the right profile depth and finish before anything is cut. Free samples are available if you want to check a finish against your existing flooring or door furniture first, and pre-drilled frames can be specified at order stage to save fitting time on site. Browse the matwell frame range to see current finishes and sizes, or check the frame depth guide if you’re still unsure which profile suits your mat. Request a sample or send your measurements today to get a frame that fits first time.

Manufacturer datasheets and installation guides

The UMFA installation instructions cover profile codes and depth compatibility. The Forbo measuring guide explains non-rectangular measuring templates and clearance tolerances.

Sources

Matwell frame for entrance matting (Slip-Not product page)

FAQ

What are the standard mat frame sizes?

The three most common pre-cut inside-opening sizes are 0.61m × 0.36m (small), 0.69m × 0.41m (medium) and 0.76m × 0.46m (large), figures used consistently across retail matwell product listings. Profile depth (typically 12mm, 17mm or 25mm) is chosen separately based on your mat thickness.

What size should a matwell be?

A mat well should measure at least as large as the mat you intend to fit, plus a small clearance gap of around 3 to 4mm on each side so the mat sits flush without binding against the frame. The depth of the well should match your chosen profile depth so the mat doesn’t sit proud of or below the surrounding floor.

What is the size of a standard doormat?

Standard doormats generally correspond to the same inside-opening brackets used for matwell frames, roughly 0.61m to 0.76m in length and 0.36m to 0.46m in width. Always measure your specific recess rather than assuming a doormat bought off the shelf will match an existing matwell exactly.

How can I get a custom doormat size?

For a recess outside the standard three sizes, order a bespoke cut-to-size frame and mat rather than forcing a standard size to fit. Qualitycarpettrims can cut solid brass frames to a specified inside opening once you provide accurate width, length and depth measurements, including for irregular or non-rectangular wells.

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