(all folds inline when pulled up)  



Blind Layout

Bottom of blind to rod pocket
diagram indicative only - not to scale or propotion



How to use this calculator

  • Enter the following values in cms.
    • Finished Blind Length
    • Headrail Allowance*
  • Select a number of Fold Sections (must be an odd number)
  • Press "Enter" to calculate
  • If necessary change the number of Fold Sections and/or headrail allowance and recalculate until you find the best "Top Section length" for your blind.
  • Varying the Headrail allowance will help you get the "Top Section" depth right. (Caution: If you make the headrail allowance too small the blind may not pull up properly * )
  • Note the more fold sections you use the thicker the blind will be when pulled up. (using too many may cause problems, with the blind sticking outwards when pulled up)

* Please see our BLOG item Headrail allowance explained for more information on headrail allowances.

Making your own blind? Learn how to get a professional finish

This blind calculator is designed to compliment our free tutorial instructions on how to make a lined, interlined or blackout Roman Blind. Read the tutorials here to learn our Professional workroom method.

Questions & Comments


The blind I want to make doesn’t have to be lined. What allowance would you suggest for each rod pocket please?


Thank for this amazing resource. Super easy to use and much quicker than bimbling around with a calculator. Much appreciated.


How do you make the pleats hang with a really crisp edge?


There are 3 blind tutorials on the website, detailing our making methods, plus videos as well.



Thanks for this so helpful - but what i am after is a final fabric amount i need to order? does this appear anywhere on the calculations? As i cants ee it?

or shall i just add up all the individual measurements and hope this covers it?

thanks so much x


Try this BLIND FABRIC CALCULATOR or look at our free tutorial instructions that take you through the calculations step by step.





love the calculator, but why is it I can only print out the calcs for straight blinds? When I try to print cascade calcs I just get a blank page?


The calculators and website are slowly being developed I'll put it on the request list.


Do you have this calculator in inches?


No it is a decimal calculator in cm. We work on cm in the UK some are not sure how you deal with the fractions of an inch. If we made the calculator in inches would you expect the results to come out as a decimal or fraction. for example if the result was 65 and one quarter inches would you expect the result as 65 1/4 or is 65.25 just as good.


decimal would be just fine, i.e., 65.25. I'd love to see it in inches, too!


Thank you for your tutorials. Just wondering if you have a cascading calculator formula that can be worked out on paper instead of the online calculator?

Thank you


There is a formula behind the calculator, I'm afraid it is not something I have written down anywhere. We just use the calculator as it is so quick and easy.


the formula is...

drop minus the headrail allowance

divide by fold sections = fold depth

sew your roman tape every 2 sections apart from the odd one at the base which only has one section.


That is nearly right for the standard folds (all sections inline) roman blind calculation, you are missing that the number of fold sections has to be an odd number or the blind will have no bottom flap. That calculation method (formula) is covered in detail in STEP 2 of our roman blind tutorials. You can read it  HERE

The formula for a cascading blind is more complicated as the fold sections are not all the same depth and vary according to the cascade increment and number of fold sections. The cascading blind calculator is HERE

Wes Shepherd

This is really useful and will certainly help going forward.

Is there anyway to incorporate in the calculator a field stating how much you want to see of the bottom pleat? - for example if there is a contrast border of 5cm at the bottom you would want that to be seen and not go up behind the blind fully

This would be really helpful


Yes go to the other calculator on the site the CASCADING BLIND CALCULATOR set the cascade increment to zero and the bottom flap tp 5cm.

Wes Shepherd

Thank you thats great


Many thanks for all the useful information here. I wanted to check the headrail allowance for an outside the recess window. Our batten sits well above the window: from the top of the wooden batten to the plaster around the window, it is 10.7cm. Hope that makes sense! Do I need to add another 3.5cm to this to calculate the headrail allowance? I am concerned that if I don't, there won't be enough room to pull up the blind. Many thanks for your advice.


Hi your question implies you don't understand what the headrail allowance is. There is an explanation in the tutorials HERE and an article in our Blog explaining headrail allowance HERE

Have a good read of those 


Is there a blind kit brand that you recommend? I have made a few in the past and they were a bit flimsy and the cords came unstrung. Do you have a brand you go to when buying the headrails, etc?


We use a trade only brand. Try Merrick and Day Deluxe its probably the closest you can buy retail.


How fantastically helpful. I sat for hours trying to understand the book I have about making different window treatments. Phew! Thank you so much and enabling one to print out makes it super easy to work with later.


I am making two face fix blinds for my dining room. The top of both windows is 188cm from the floor but the drops are different. One is 131cm and the other 145cm. How can I achieve the same top section and pleat measurements or as close as possible? Thanks


Hi Amanda

This is simply a calculation. You just need to play around with different pleat sizes, along with your headrail allowance, until you get 2 similar amounts for top section. You will need to adjust the headrail allowance on 1 (make it bigger) to give you the correct top section.
For example - For the 145 cm blind you could have pleat sections of 9 pleat sections of 15.3 cm ( 137.7cm), headrail allowance of 7.3 cm (top section of 22.6cm)
For the 131 cm blind you could have 9 pleat sections of 13.5 cm ( 121.5cm), headrail allowance of 9.5 cm ( top section of 23 cm).
It’s the headrail that will need to vary. Please make your own calculations though as we cannot accept responsibility for any example calculations.
On blind no 2, 7 pleat sections won’t give you the option to match top sections.
Good luck and send us a pic.
Kind regards

Hello! When calculating the rod pocket locations, you add 2cm for the hem allowance on the face fabric. Is this distance then the fold line or sew line for the pockets? If you fold at that distance would you need to add 1cm due to it being 1cm from where you sew?

Thanks in advance.

would you add 1cm for each one in addition to the 2cm (hem allowance) due to the


This calculator calculates the rod pocket positions from the bottom of the blind.

The tutorials explain the making methods (lined and interlined are different) The tutorials explain and the videos demonstrate how to sew the rod pockets in. You need to refer to the instructions of the actual type of blind you are making.

Leanna Adkin

This is brilliant! I've used it a few times and its saved so much time and the working out is the bit I hate! Please don't ever disappear I need this calculator forever! Thank goodness I found you!


I've used your site in the past for triple pleat lined curtains, cushions and roman blinds. This time I would like to sew a 1cm line of trim at the bottom of the blind and wondered if the best way is to add in 1cm to the material as I don't want it disappearing into the pleats when pulled up.


The blind plus the trim needs to be the finished blind length you require from your window measure.

Subtract the depth the trim will hang below the blind from this finished blind length. Then calculate your pleats etc on that new length. Make the blind to that new length, then add the trim to the bottom of the blind. The blind will then pull up with all the folds inline and the trim hanging below the fold line. When down the blind will be the finished blind length you needed from your window measure.

Tricia Griffiths

Just brilliant - thank you!

Elspeth Moore

Many thanks online calculator made it so easy to complete blinds in faster time.

Cyndy Hampson

I have been making Roman blinds for years and wish I had found your site sooner. It is fantastic and cuts down on calculation time. Thank you!

Sue Pridgeon


I want to make a cascade RB.

Can you do the calculations for me please?

Finished Drop 86cms

Headrail 6cm

7 folds

Cascade 2.5

Top 1/2 section 14.5cm

Many thanks



No  -  I'm afraid we do not have time to make calculations for people.

We have made a FREE cascading roman blind calculator on the website though. You should be able to make your calculations using that.



Thanks for such wonderful tutorials.

I'm making two blinds  located side by side in my sitting room. One has a drop of 212cm and the other, 167cm. I'm having difficulty in getting the measurements for the pleat sections for both, so the the rod pockets are at the same level on both blinds.

Regards, Ana


To get this to work the difference between your blinds (212 -167 = 45cm) will be an even number of pleat sections eg 2,4,6 etc. Therefore in this case I think you will be looking to try and have pleat sections of 45/2 = 22.5cm or 45/4 = 11.25cm.

You now need to go into the calculator with the 167cm length blind and adjust the headrail allowance and number of pleats to get either the 22.5cm or 11.25cm pleat size you want to go for.

Eg taking the 22.5cm pleat size

167cm length blind with 7 pleats, 9.5cm headrail allowance gives Top section of  32cm pleats 22.5cm

You would then put the same figures in for the 212cm blind but with 2 more pleats (eg 9 pleats) that should then work.

212cm length = 9 pleats, 9.5cm headrail allowance gives Top section of  32cm pleats 22.5cm

Effectively the same blind as the 167cm one except with 2 extra pleat sections.



Your tutorial is excellent but I've a question about the headroom allowance that isn't clear.

You explain you must leave enough room for eyelets, battens etc but how much?

Is there a rule of thumb to say X number of battens should need Y headroom allownance on top of the 5cm?

Clearly, 5cm for a big blind with lots of battens isn't going to be enough, but I would like to keep it as small as possible but how to know?

And if you allow too much does that make any difference apart from how it looks?

Thank you very much.


Go to our Blog and read "Headrail Allowance Explained" There is info an photos there that wiil help. You will see there is an absolute minimum but using more works fine.


Hi, I'm making two blinds that will hang side by side, one for a kitchen door and one for the kitchen window next to the door. The kitchen door window has a drop of 115cm and the window next to it has a drop 97cm.

I am trying to calculate the pleat sections and the rods so they will line up together. Is this possible? I'm just wondering whether it would look odd if the rods and pleats don't line up. Could I have the bottom pleat section 18 cm longer on the door?


I think you could do this, each blind would be 25cm deep when pulled up.

1 blind 16cm headrail allowance plus 9 x(9cm sections) =97cm

other blind  16cm headrail allowance plus 11 x(9cm sections) =115cm

I assume they will be attached at the same level, as the most important thing to focus on is that they are aligned when pulled up.


Fantastic site, saved me hours of calculations. Thankyou.


My finished length of blind is 116 cms, headrail 4cms. I chose 7 pleats but it is coming up as error even if I choose more or less pleats. Please help


The headrail allownace is NOT the size of the headrail, you have to allow extra room beneath the headrail or the blind will not fully pull up. The online CALCULATOR uses a minimum of 5cm for the headrail allowance that is why you are getting an error message. If you read the tutorial STEP 2 it explains the headrail allowance.

I'll put a note the calculator uses a minimum of 5cm in the text - as in the tutorial. 


Hi, My concern is the headrail. I have given 10 cm for this allowance but the wood im using is 5cm x 5cm. With the depth of the eyelets it still wont measure to 10. I am thinking i can pull the blind up to the desired place but just want clarification this will be ok. I chose 10cm as i put in a calculation for a cascade blind, and this figure was suggested. It looks fine after being pinned up and folded to see what it would look like, i am just concerned when i pull up the rods they will want to go up to the eyelet depth.


You are thinking right!

10cm allowance is good for your 5cm deep headrail face. Dont worry about there being some extra space to the eyelets, the blind will only pull up as far as you pull it. So you just pull it up until the pleats are where you want them and hold it in that position, you don't have to pull it up with rods tight to the eyelets.

Your headrail is deeper than most, our wooden ones are 3cm deep. The calcuator uses a minimum of 5cm for the headrail in it's calcuation.


This is my 1st attempt at making a roman blind. I want it to sit inside the recess of the window & my blind measurements are 68cm wide x 112cm drop. I've been trying to work out the fold measurements & I think that with a headrail allowance of 7cm, I could have pleat sections of 15cm depth or with a headrail allowance of 7.5cm, I could have pleat sections of 9.5cm depth. I note that you say folds are usually 10-25cm but I wondered if this mattered with a small window. Could you please advise which would be better


9.5cm folds should work. Without seeing the window we don't know which will look better. With those figures one will have a top section (blind size when pulled up) of 22cm and the other 17cm. Obviously the 17cm wiil have 2 extra rod pockets and consequently 4 extra panels of fabric when pulled up, so may stick out quite a bit more when up. 

Put a bit of paper 22cm wide and 17cm up at the top of the window and see which one you think will look best. 


I am making a blind 200cm finished length.

I have used your calculator which suggests 7.5cm head rail allowance and 17.5 cm each Pleat section with 5 rods.

How does this take into account the bottom hem pocket for large rod?


The results are for the size of the blind folds. The bottom fold includes the hem. There is a comprehensive FREE written tutorial on the site on how to make a roman blind.


I have NaN in all the boxes except no. of rods, what have I done wrong ?


NaN is an error message meaning NOT A NUMBER. It will occur if you enter cm15 etc instead of 15 or 15cm in the input boxes as the calculator thinks you have entered text not a number.

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