Ordering the wrong size drawer runner is one of the most common, and most avoidable, mistakes in a DIY kitchen repair. A runner built for one clearance won't perform properly on a drawer that doesn't match it, too tight and the drawer binds, too loose and it won't close fully or run smoothly. This guide walks through exactly how to measure your existing drawer and cabinet, step by step, so the replacement runners you order actually fit the first time, rather than arriving and turning into a second trip back to the shop.
What you'll need before you start
You don't need specialist tools for this, a tape measure, a Pozidriv or flathead screwdriver, and a pencil to note down your measurements as you go. Working through the drawer in a consistent order, length, then width, then height, keeps you from missing a measurement or mixing up which figure belongs to which dimension once you're comparing several drawers. If you're measuring more than one drawer, it's worth sketching a rough table on paper as you go, drawer by drawer, rather than trying to hold every figure in your head until you've finished the whole kitchen.
Step 1: Remove the drawer and identify the mounting type
Pull the drawer out as far as it will go, then release it from its runners, most systems either lift off with a firm upward pull once fully extended, or use a small release catch on each side. If the drawer won't come free with a straightforward pull, check for a locking lever or catch near the back of the runner before forcing it, some systems need this released first.
Take a moment here to identify the mounting type before you start measuring, this genuinely changes which measurements matter most. Side-mounted runners fix to the sides of the drawer box with two visible components running along each side. Undermount runners sit beneath the drawer for a cleaner, hidden look, with the mechanism largely out of sight once the drawer is closed, these typically require the drawer side length and thickness to fall within tighter stated tolerances than a side-mount system. Centre-mount runners, less common in modern kitchens but still found in older cabinetry, use a single runner mounted along the centre of the cabinet base rather than one on each side.
Step 2: Measure the closed runner length, not the drawer front
Drawer runners are sized by their closed length, the measurement that needs to fit inside the cabinet, not by the length of the drawer front itself. Measure from the very back of the drawer box to the front, deliberately excluding the drawer face, since the face extends beyond the box and isn't part of what the runner needs to support. This is genuinely the single most common measuring mistake, the drawer front is the easiest part to get a tape measure around, but it isn't what determines runner length.
UK drawer runners are commonly supplied in standard closed lengths, 350mm, 400mm, and 450mm are typical across most ranges, though longer runners exist for deeper drawers. Once you have your measurement, round down to the nearest standard size rather than up, a runner slightly shorter than the drawer box is far less of a problem, it simply sits a little further forward, than one that's too long to physically fit inside the cabinet at all.
If you're replacing runners on more than one drawer, measure each one individually rather than assuming they're all identical. Even drawers in the same unit can vary slightly, particularly in an older kitchen where cabinets may have settled, been adjusted, or been repaired unevenly over the years. A five-minute shortcut that skips individual measuring often costs more time later if even one drawer turns out to be a different size.
Step 3: Work out the installation width
This is the measurement most people get wrong, and it's the one that actually determines whether your new runners will fit properly on both sides. Measure the width of the drawer opening in the cabinet, then measure the width of the drawer box itself. Subtract the drawer box width from the opening width, then divide the result by two, this gives you the clearance available on each side for the runner itself.
For example, a 300mm opening with a 274.6mm drawer box leaves 25.4mm total, or 12.7mm clearance per side, a commonly used industry standard figure worth checking your own runners against before assuming a generic replacement will fit. Getting this figure wrong in either direction causes real problems: too little clearance and the drawer will bind, drag, or refuse to sit flush against the cabinet front, too much and the drawer will feel loose and may not track smoothly along the full length of the runner, sometimes rattling slightly even when fully closed.
Step 4: Check the mounting height and fixing positions
Measure from the bottom of the drawer box to the point where the runner actually attaches, since this determines how high the corresponding cabinet-side runner needs to be fitted. Getting this wrong means a drawer that sits crooked in its opening even if the length and width measurements were both correct.
While you have the old runner off, note the position of its fixing holes or bracket points too. If your replacement runner uses a different fixing pattern, you may need to fill and re-drill rather than reusing the existing holes, this is worth knowing before you start rather than discovering it mid-installation with the drawer already half-apart. Photographing the old runner and its fixing positions before removing it fully is a genuinely useful habit, giving you something to check the new hardware against later.
Step 5: Measure the cabinet's internal depth
Check the clear internal depth of the cabinet itself, from the back panel to the front edge, accounting for anything that might reduce the usable space, a door, a back panel that sits slightly proud, pipework, or hinges intruding into the cabinet interior. This confirms the runner you're planning to order will actually have room to extend and retract fully without obstruction, particularly important on a full-extension runner, which needs to travel further out of the cabinet than a standard three-quarter extension type.
What if your old runners are damaged and hard to measure accurately?
If the existing runner is bent, broken, or missing a section, measure the drawer and cabinet openings directly instead of relying on the damaged hardware itself, the drawer box and cabinet opening are the more reliable reference points in this situation. It's also worth measuring the undamaged side of the same drawer if only one runner has failed, since both sides should, in theory, match, giving you a useful cross-check against your other measurements.
Common measuring mistakes worth avoiding
The most common error is measuring the drawer front instead of the drawer box, since the front is what's visible and easiest to reach a tape measure around, but it isn't what the runner actually needs to match. The second common mistake is measuring only one side of a drawer and assuming the other side is identical, small variations happen even within the same unit, so it's worth checking both sides properly rather than trusting symmetry. The third is rounding a length measurement up rather than down when it falls between two standard sizes, a runner that's slightly short still generally works, one that's too long often won't fit inside the cabinet at all. The fourth, easy to overlook, is forgetting to check the fixing pattern, a runner that's otherwise the right size can still mean an awkward install if the screw positions don't line up with what's already there.
Once you've got accurate measurements for length, width, and mounting height, our guide on how to fit drawer runners properly covers the actual installation process, including how to fit the cabinet-side and drawer-side components correctly and avoid the alignment issues that cause a newly fitted runner to stick. If you've measured up and are ready to choose new hardware, our Ball Bearing Runners offer a smooth, durable, full-extension option with soft close as standard, genuinely suited to a heavier kitchen drawer, and our full Drawer Packs, Runners & Accessories range covers side-mount, undermount, and D-Motion options if your measurements point to a different mounting type than what you're replacing.
Frequently Asked Questions
1. Should I measure the drawer front or the drawer box for a replacement runner?
Always measure the drawer box itself, back to front, excluding the drawer face, the face extends beyond the box and isn't part of what the runner needs to support.
2. What standard lengths do UK drawer runners typically come in?
350mm, 400mm, and 450mm are common standard closed lengths, once you've measured your drawer box, round down to the nearest of these rather than up.
3. How do I calculate the correct installation width for a new runner?
Measure the cabinet opening width and the drawer box width, subtract the drawer width from the opening width, then divide by two to get the clearance available on each side, commonly around 12.7mm per side on a standard fit.
4. What happens if I order a runner that's slightly too long for my drawer?
It likely won't fit inside the cabinet at all, or will prevent the drawer from closing fully, always round a length measurement down to the nearest standard size rather than up.
5. Do I need to measure every drawer in my kitchen individually, or is one measurement enough?
Measure each drawer separately, even drawers in the same unit can vary slightly, particularly in an older kitchen, so relying on a single measurement across multiple drawers risks an inaccurate fit on at least one of them.
6. How should I measure for a replacement if my old runner is too damaged to measure accurately?
Measure the drawer box and cabinet opening directly instead of relying on the damaged hardware, and check the undamaged side of the same drawer, if only one side has failed, as a useful cross-check.
