How to make -
Interlined Roman Blind
Step 2: Calculate the Blind Dimensions
Printable Worksheet
Printable Worksheet

You now have the finished blind width, length and a preferred Top Section Size. Next you need to calculate the number of rod pockets on the back of the blind and their positions. This will determine the style and depth of the blind when it is pulled up.


The making process is the same for all 3 styles of blind, the only difference is the calculation of the number of rod pockets and their positions. In our tutorial videos we will be making a standard folds blind where flaps all line up in the up position. If you are making a cascading blind or a blind with an extended bottom flap, see the links at the bottom of the page for some extra information.


First we need to establish the Headrail Allowance

The headrail allowance must be sufficient to cover the batten/headrail face and allow enough room under the blind for the folds to pull up to the correct position..

We use a minimum of 6.5cm for headrail allowance for our headrails. As a general rule use an absolute minimum headrail allowance of:

Headrail mechanisim: Headrail depth + 2.5cm
Traditional wooden batten: Batten face + 3.5cm

Please see our BLOG entry HEADRAIL ALLOWANCE EXPLAINED for more detail


  • Deduct the headrail allowance from the finished blind length to give the amount of fabric to be folded.
  • Divide the length of fabric to be folded by an odd number of fold sections - this will be the fold depth for that number of fold sections.
  • Add the headrail allowance to the fold depth to get the Top Section size.
  • Find the odd number that gives a Top Section size nearest your preferred Top Section size.
  • The odd number that was closest is now your number of fold sections and the answer in (2.) is now the depth of your folds.
  • The number of rod pockets = (number of fold sections -1) divided by 2


  1. When choosing the best Top section size also consider your pattern if using patterned fabric. If possible choosing a depth that gives the best pattern placement when the blind is up.
  2. Adjust the headrail allowance slightly to tweak a Top section size. (never below minimum). Eg when trying to get 2 blinds of slightly different lengths the same size when pulled up, or getting the Top section the perfect size for the pattern.


With the number of rod pockets (3) and fold depth (12.0cm), we can now calculate the rod pocket positions

Try our online calculator to check your figures.


To calculate the rod pocket positions for a cascading blind please use our FREE Cascading Roman Blind Folds Calculator

To calculate the rod pocket positions for a blind with a bottom flap please use our FREE Cascading Roman Blind Folds Calculator

Enter your bottom flap size and a cascade increment of 0. The folds will then all line up with just the bottom flap hanging lower when the blind is pulled up.


Yes that is normal,standard folds form a very slight cascade due to the way the rods and rings stack on each other when the blind is pulled up. The calculation of the rod pocket positions means that if the rods were all pulled up to exactly the same height, all the folds would be exactly inline. (see image)

However that is not how a blind pulls up, the rods and rings stack on each other on the cord which creates a very slight cascade. If you were really wanting to make the folds line up exactly inline you would have to make make an adjustment to your rod pocket position calculation . It would involve making a mock up to see what the slight cascade depth is caused by the type of rod pockets and ring/breakouts you are using. Then recalculating the rod pocket positions to adjust for this. (this is not something we do)

Questions & Comments


Hi I am making a Roman blind length 208 cm width 109 cm , if you were to make it how many rods would you use .


Either 5 or 6 depending on preferred top section.


Nicola Hales

I am making 4 blinds for a side window and front facing window for both the LH side and RH side of the breakfast room. My side window on the left is narrow and only requires one width of fabric but the other three are finished width of 165cm. I therefore need to join my 135cm width fabric to another piece, and match the pattern. Is it okay that this seam will be to one side or am I better off to have a central seam for these three blinds? I just need guidance so I can order the correct lenth of fabric.


We never join down the middle. We always make a balanced blind with a central panel and equal amounts added to each side. You will also need adjusted cut drops to join patterned fabric. We will be looking to add extra information for making wide r than one width blinds to the website shortly.

Ann Parry

This is amazing thank you so very much.

I have always been unsure how or should I say where to put my rod pockets but think I have finally got it luckily I came across this information, as I wanted the folds to cascade slightly, if I hadn’t seen this I would have not got that effect,I cannot thank you enough.

Also I am making them for my daughter so she too would have been disappointed but would never have said to me.

Once again thank you.


Ann Parry. Xx????


I want my blinds to be outside the recess and be interlined. Is it best to have fewer folds if they are interlined? I'm just trying to work out how far above the window they will need to be positioned


Interlined blinds are thicker than lined, the more folds you have the more likely they are to push out when stacked at the top. Up to 3 or 4 rods ( 5 or 7 pleat sections) usually works fine, on long blinds we have done more.

The thickness of your fabric and the thickness of the interlining is a factor. You will see in the videos we use a fine interlining.

Caroline Warwood

Hello I'm confused about the head rail you not just measure the depth of the roman blind cassette attachment. I normally deduct 5cm. Is that right?


We add a lttle bit more than the depth of the cassette attachment (x 1.5) to allow for some room for the rings of the blind to pull up underneath when the blind is fully pulled up.

The tutorial is also for a traditional wooden batten headrail with ring eyelets underneath. The extra room underneath is more important here as the rings only pull up to the eyelet not the bottom of the batten.

Ann Whettingsteel

am making a recessed roman blind with bobbles on the drop edge. Do i have to make the blind smaller so the bobbles just touch the windowsill.Also so the bobbles show when the blind is fully up do I have to put a dowel rod pocket nearer the bottom of blind.


Make the length of the blind the drop you measured in step 1 minus the size of the bobbles. Calculate your pocket and folds based on this shorter length. Then attach your bobbles to the bottom of the blind.

The total blind length including bobbles should now be your measured drop. So the bobbles will just touch the sill when the blind is down. When the blind is pulled up, all the folds will be in line and the bobbles will just hang below at the front.

The bottom of the blind has a bar in it already.


I have made a roman blind where the drop is 208cm in length.

I used the calculator and went with the pleat sections and rod pockets all being 40.6cm with two rod pockets in total. My question is when lowering the blind can it stop and sit at any point of the blind (half way down a fold)or should it sit only on the folds ?


You can lower a blind to where you like. 2 rod pockets for that length blind doesn't sound enough for a conventional looking blind.

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