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Standard Bifold Doors Sizes & How To Find The Right Fit?

Bifold doors open up an interior, allow light to spread from one room to another, and generally make the home appear much roomier than it otherwise might. A bifold door consists of an intricate concertina of panels, each one attached to its neighbour via a hinge. The entire thing is fixed into a doorway via a rail. Doors of this sort are large and elaborate, and all of those moving parts will need to properly fit. In this article, we’ll take a look at the sizing and fit of your internal bifold doors in more detail.

measuring tape for doors

Bifold Door Sizes

Bifold doors come in standard sizes, ranging from 1800mm right up to five metres or more. There isn't a one size fit alls but there are several sizes that tend to fit most bifold openings. Each internal bifold door is around 2084mm tall, but you’ll need to double-check check the height of your opening. Small adjustments can be made to the frame to keep things even. But if you’ve got a nonstandard opening, then you might need to get a door especially built for the purpose. This can be expensive, but fortunately it’s not required in the majority of cases.

So, what are the standard bi-fold door sizes? Let’s take a look at a quick bifold door size chart:

Bifold Door Size Chart

No. of PanelsFrame Width (mm)
Three Panels


Four Panels


Five Panels


Six Panels


The doors described here come in a range of different configurations. There are standard bifold doors, which consist of a single stream of panels which unfold from one side of the frame; there are ‘French-fold’ doors which consist of two equal groups of panels which extend from either side of the frame and meet in the middle; and there are ‘traffic-door’ equipped bi-folds, which come with a single door on one side to allow for easy passage.

When measuring for bifold doors, precision is key. A difference of just a couple of millimetres can be significant when it comes to excluding drafts and ensuring the smooth operation of the door.

What Size Bifold Door Do I Need?

internal bifold doors

Assuming you’re not bringing in any help to measure your doors for you, you’ll need to break out the tape measure before placing your order. If you’re going to be tearing out the old frame and installing a new one, then you’ll need to figure out the width of the aperture; if you’re installing a new bifold into an existing frame, then it’s the interior dimensions you need to worry about.

How To Measure For Bifold Doors

  1. Checking Alignment
  2. Before we measure any distances, however, we should ensure that the door is square and true. This means taking a spirit level and placing it against the edges of the opening.
  3. Measuring Up
  4. Now it’s time to check your bifold door frame size. You’re going to be taking a total of six measurements: three vertical, on the left, right and centre; and three horizontal, along the top, middle and bottom. In both cases, the three measurements should be within ten millimetres of one another. The smaller the difference, the better. If you’ve got a serious discrepancy, then you’ll likely have to adjust the frame before you get the door installed (though this is less of a problem if a new frame is going to be installed). In both the horizontal and the vertical, you’ll want to use the smallest measurement. Subtract ten millimetres’ clearance, and you have the length of your door
  5. Sunken or Flush?
  6. Once you know what size you’re going for, you can think about whether you’d like a sunken track, which is placed beneath the floor level, and a flush one, which is placed at floor level. Obviously, having the track higher will mean that your door needs to be moved up out of the way
  7. Panel Sizes
  8. The panels that go into bifold doors come in various sizes. For the most part, you’ll have a choice between a large number of narrow panels and a small number of wide ones. This enormously influences the look of the door and affects the amount of light that can pass from one side to the other. But it also has practical implications. Wider panels will need more space to open out into, meaning that you’ll need to clear room on one side of the door. But narrower ones will take up more space on one side of the door when it’s open.

My Bifold Doors Don’t Fit. What Shall I Do?

If you’ve measured carefully, then the chance of a mismatch between the size of your door and the size of the opening will be minimal. Check that your doors fit the opening as soon as they arrive – if there’s a problem, the best course of action is almost always to send them back. This is time-consuming, but it’ll save you from having to mess around with saws and sandpaper to get the problem corrected.


Now, any changes you make to your door will be permanent. Make just one wrong move, and you’ll throw away the cost of your door! It’s therefore first exploring other ways of addressing the problem. For example, if you find that your door is catching on the floor as it opens, it might point to a problem with alignment rather than the size of the door itself. It’s much easier to move the pins and rails around than it is to start making changes to the panels themselves.

With that in mind, you might have already explored these options and decided that you absolutely must shrink your doors slightly. This is tricky because most bifold panels are of the ‘composite’ sort. They’re made from high-quality wood surrounding a stronger, less attractive ‘core’. If you sand all the way into the core, the results can be unsightly. Each panel comes with just a few millimetres of ‘lipping’ around the edges, and so you’ll need to be very careful.

For this reason alone, you’ll want to take a little bit off both edges of every door, rather than a lot off one. That’s before we even think about how strange it might look to have one panel slightly smaller than all of the others!

How to cut bifold doors to fit

To get this right, you’ll want to remove the entire door assembly. Do this by loosening the pivot at the bottom until there’s enough slack to lift the entire door from the frame. Then remove the hardware and lay the panels flat.

Next, we need to do a little bit of basic maths. You need to find the difference between the current width of the entire door and the ideal width. This is the amount of timber you need to trim. You need to then divide this figure by the number of panels in the door, and by two (the number of vertical edges each panel comes with). This figure, which should ideally be in the low millimetres range, needs to be removed from each edge of each door in the set.

We’re almost ready to start trimming our bifold doors to fit. But before you start cutting, you’ll need to very carefully measure and draw the new edges with a pencil onto both sides of the door. Use masking tape to clearly mark your edges, and score along the line with a Stanley knife. You’ll then be able to saw along the edge, leaving a little bit of space so that you can sand the edge smooth after you’re done. In some cases, you might not even need to use a saw.


When they fit properly, bifold doors make a fantastic addition to the interior. But adjusting them can require painstaking work. It’s therefore worth taking the time to get it right when you first go to measure up!