Step 2: Calculate the Blind Dimensions
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.
DETERMINE YOUR HEADRAIL ALLOWANCE
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 + 2.5cmTraditional wooden batten: Batten face + 3.5cm
Please see our BLOG entry HEADRAIL ALLOWANCE EXPLAINED for more detailSTANDARD FOLDS CALCULATION
- 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
PRO TIPS
- 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.
- 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.
ROD POCKET POSITIONS
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.
EXTRA INSTRUCTIONS
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.
FAQs
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)
Your Questions & Comments
Hi, I have made my conservatory blinds and am unsure how long to leave the blind cord before I add my silver blind cord weight. Should I make them sit at eye level or down resting on the window frame?
If I do the second idea Ill have loads of blind cord to wind as the blinds are about 115cm down.
The blomd weights are quuite large bell shapes and I dont want them to jut the blinds forward.
Or I could put longer cord through them and let the weight dangle beneath the window frame into the plaster, but it would look messy anf have never seen that anywhere.
You need to be able to reach the cord weight when the blind is down.
Due to child safety rules, in the UK the cleat must be at least 150cm from the floor and all the cord must be wrapped around the cleat.. More info here
ROSPA blind cord safety
Hi. I want to make a Roman blind for a door in a recess. The space above the door is only a foot. Is it possible to calculate the finished length of the blind when is is up so I can be sure it will pull up into that foot of spare space and clear the door? Or is it trial and error! Thank you.
The size of the blind in the up position will be the "headrail allowance" and one "pleat section". Decide what your ideal pleat section size is and work throught the calculation to get the blind the right size above the door. Note you can always vary the Headrail Allowance (there is a minimum) to get the blind the exact size you want in the up position.
I am making 6 roman blinds for a square bay window. 4 are 56" long and 2 are 80" long. How can a calculate the folds so they long and short ones look nice when raised as some are side by side? They are all to be raised to the same level.
I'm afraid we do not do calculations for people. But with this problem I would be looking along the lines of working out how I want the 56" blinds to be (fold size and top pleat size). Then jiggle the figures so the fold depth of the 56" is an exact even multiple of the difference between the 2 size blinds. (Ie 80-56=24) so 24" divided by the fold depth is an even number.
That would mean your 80" blind would have exactly the same top pleat and fold sizes as the 56" (it would just be a few sections longer).
I would like the folds to be staggered when blind is up rather than standard. How do I calculate this?
The position of the rod pockets determines this, there is a cascading blind calculator on the website to help you calculate the rod pocket positions to give you the effect you are looking for.
CACSADING BLIND CALCULATOR
I am going to attempt Roman blinds for my patio doors and windows either side. Do you think it will be possible to make them look right as the fabric for the door will be quite a bit longer? Also I prefer the look of cascade blinds, do you think this is an option or should I stick with standard?
Many thanks.
We would generally make them so they are all the same size when pulled up ( something that will take some thought with cascades - for the bigger blind you would probably have to have the same cascade as the smaller windows and then pleat the excess level with the bottom of the cascade.)
There is a picture on our Pinterest "What You've Made" board of a set of three blinds made by somebody. 2 short 1 long at a patio door.
I am making two blinds @52.5inches drop. What size of spaces would recommend for that drop approx .thanks georgia
The spacing determines the size of the blind when it is pulled up which is a design decision you have to make taking into account the room and the window.
Try the free calculator on here, you can keep changing the fold size, and it tells you what you need to know
I would like to make cascading roman blind and trying to work out number of folds. actual drop is 160cm finished length
Have you tried using the "Roman Blind Cascading Folds Calculator" on the website?
CASCADING BLIND CALCULATOR
Which size blinds would work out the best:-
2 blinds 127 cm wide by 205cm drop or 4 blinds 73.5 cm wide by 205 cm drop. Just a little concerned that 2 blinds made of a firm weight good quality cotton with cotton linings might be difficult to operate with the weight?
The number of blinds depends on the design of the window. (design choice),
Generally with 2 panels go with 2, 3 panels go with 3 etc.
As for the weight, a good quality headrail mechanism should work, You may need a geared mechanism, they should advise what weight they can pull up.
I purchased the roman blind kit which came with 5 rods. My window measurements is 90cm width and 129cm drop. Do I need to use all 5 rods as according to the calculations 4 rods should be sufficient.
Appreciate your advice please.
Go with the number of rods that will give you the best pleat size for your blind. I suspect your roman blind kit has 5 rods in it so it is good for making a short blind through to a longer blind than the one you are making.
Our online Roman blind calculator on the website will quickly show you the pleat section sizes for the number of rod pockets used. Also remember you can adjust the headrail allowance you use to get the Top Pleat Section size how you want it.
Why dont we use a rod for every fold? Surely this would look neater and the weight would keep the material hanging nicely.
The rods are for pulling the blind up, not forming the folds which should naturally form as the blind pulls up. When the blind is up they are all effectively hidden at the top and back of the blind.
I have never seen a roman blind with the rods on the fold lines as you describe. It would not enhance the blind.
My finished length is 161 cms, Ive worked it out 15 .5, 31, 31 , 31 , 42.5 with a head rail allowance of 10 cms , is this ok , how would you work it out
Your figures are a little confusing, not sure where the 42.5cm plus a headrail allowance of 10cm is coming from. But I think you have calculated a top pleat section (pleat plus headrail allowance) 37cm deep when pulled up on a 161cm window.
(effectively a 21.5cm headrail allowance with 9 pleat sections of 15.5cm and 4 rod pockets.)
Hold a tape up to the window and see what you think. Whether it would block too much light or look right with the fabric pattern etc. Only you can decide that.
Have you tried the online Roman blind calculator. You can always vary the headrail allowance to make the top pleat section the size you want and change the pleat sizes to whole numbers.
With your 10cm headrail allowance
9 pleat sections would give 4 rod pockets, the top pleat section 26.78cm and other pleats
sections of 16.78cm.
But for example if you adjusted the headrail allowance to 8cm this would give a top pleat section of 25cm and other pleat sections of 17cm.
At the end of the day you have to decide what will look best at your window.
Im making blinds for 2 windows side by side. One is 147cm long and the other 147.5 cm long? If I aim to make each top pleat identical depths, what should I do about the extra 0.5cm? Ignore it? Love this website by the way!
We had this the other day in the workroom. What we did was keep the top section of each blind the same by using the same headrail allowance. The pleat sizes will be obviously be slightly different but in your case by only a millimetre or so which you wont notice.
I have a small window in my porch 110 cm wide X 53 cm drop. I thought about a roman blind (inside)but am wondering if it is too small an area for a roman blind
We've never made a blind with such a short drop. It's possible with small pleats but it would be worth looking at how it would look and how much light it would block out in the up position before you make it. We would usually make the blind outside the recess in this situation with it fixed above the window so when pulled up does not block out much light.
Hi
Thanks so much for this helpful website. Is there a maximum number of rod pockets a blind can have? I have quite a long drop and would like 9 folds - 4 rods. Just a little nervous in case this the bulk of all these folds is too deep to sit smoothly behind the first fold?
For a lined blind with normal weight fabric, 4 rods will be fine, that is a very common number of rods we use in the blinds we make up.
I have six roman blinds to make for one room. All blinds are going to be hung adjacent to each other. I want all the blinds to be hung at the same point, 10cm down from the ceiling and I want them all to look the same when folded up. Unfortunately there is a difference in the drop for each window. The difference from first blind the sixth blind is 1.75cm. I think I have worked out how to make the top pleat the same for all blinds by altering the rod spacing across the blinds. This means when open, they will look the same, but the rods wont line up across the blinds. Do you think this makes sense? Will it matter that the rods dont line up?
The most important thing is to get the top pleat sections all the same so the blinds all look the same when they are pulled up. You will obviously have the same number of rods for each blind. The 1.75cm will make a small difference between the pleat section sizes. You have 2 options
Remember to keep the top pleat section sizes the same and ensure you have a big enough headrail allowance to make sure the blind can be fully pulled up. We would probably go for option 2.(there's no right or wrong answer). If you look at our facebook page another sewer has commented they had the same problem and said option 2 worked perfectly.
Hello, am a little confused at what will work best. My window is 192 cm in length and the wizard has given me a number of options. What would you suggest?
Many thanks
Rachel
It's all about design decisions and really that comes down to personal choice. The 2 key things to decide are.
Hi there, thank you so much for your site, I am making a 100cm drop by 60cm (finished width and length) a small roman for the toilet, could you please tell me how many rods I need and distance apart each, I am hoping to get at least 3 rods. I have tried the calculator but keep getting error and am tearing my hair out! any help would be great. Many thanks.
Hi Jane, the number of rods is half the number of pleat sections minus 1. So for 3 rods you will need 7 pleat sections, 4 rods 9 pleat sections etc. An error message comes up on the calculator if you put in figures that are impossible to calculate. (for example a 100cm blind with 3 pleat sections cannot be 15cm deep when pulled up)
You need to decide how deep you want the blind when it is pulled up, for your 100cm blind if you decide you want a 20cm top pleat section depth and 7 pleats sections for your 3 rods the calculator will give you the answer of
I am trying to make a 100cm drop roman blind - but my wooden baton is only 3 cm - so my calculations won't go into your calculator. So I have worked out that 19cm at the top and 31.5 cm with 20cm at the bottom. Is this correct.
Your figures don't make sense i'm afraid.
The Headrail allowance is not the size of the headrail. It is the distance from the top of the blind down to where the folds form. It includes extra space under the headrail to make room for eyelets (with a wooden batten) and stop the folds pulling up into the headrail. We advise 1.5 times the batten size and a minimum of 5cm for the headrail allowance. (All the info is in the instructions above)
I would like to hoist my blind high to allow max light into the room. I am hanging it outside the recess and judge that the batten can be fixed 10cm above the window (there is 32cm total space to the ceiling. The finished blind drop is 129am & width 70cm. I wonder whether I could have fold depths of 11.25cm, which would mean 11 folds and 5 rod pockets. Do you think this would work or is it too many folds? Thank you.
If you are hanging the blind above the recess and the batten is tight against the wall the folds will push against the wall and probably outwards if you have 5 rod pockets. Obviously the thicker the fabric the more they will push out.
As to whether this will work we can't say not knowing the your fabric, thickness of batten how you are going to mount it etc.
Hi there,
When you have sewn in all your rod pockets on the lining how much fabric should be left at the top above the last rod pocket? One fold (i.e. the length between rod pockets) the 5cm heading allowance and the headrail allowance? I've become a little confused about the length of the folds calculated in step 2. I had 143cm amount to be folded (finished blind 149 - 6cm headrail allowance) and want 10cm folds. I divided 143 by 13 which equals 11. Do I then separate my rod pockets my 22? Or 20?
Above the last rod pocket will be 2 pleat sections (which form 1 fold), the headrail allowance, plus the 5cm heading allowance.
If you go for 20cm rather than 22cm gaps afteryou've made your calculation, you will end up with a bigger headrail allowance and the blind being deeper when pulled up. (try different headrail allowances and different numbers of pleat sections in the "Roman Blind Fold Calculator" on this site) until you get the nearest answer to what you want.
Hi I'm planning to make cascading Roman blinds, with a cassette kit. I would prefer to have a couple of pleats still in place at the bottom of the blind when the blind is fully let down, as I don't like the completely flat look. Presume I achieve this by just making the blind longer than the window, by allowing fabric for a couple of 'extra' pleats? Thanks
That should work.
My blind needs to be 243cm wide - is this too wide to do as one blind?
It can be done.
We personally don't think wide roman blinds look good though and they are more difficult to make as well,(especially if you are a beginner and dont have a big table)
I have a drop of 160cm width 2metres, not sure what would look better 3 or 4 rod pockets with 17.2 pleat or the 22cm pleat, cannot visualise, as a professional company what would you go for?
It depends on the window, it's setting, the fabric you are using, thickness of lining/interlining, how much light you want to block out etc. Put a tape up to the window and see how big the blind will be when pulled up, (top pleat section) and make a judgement. We would go for 4 rod pockets.
What determines the headrail allowance do they come in different sizes.
Headrails and battens do vary in depth, but the headrail allowance isn't just the depth of the batten/headrail.
You choose a headrail allowance and it has an affect on the size of the blind when pullled up, (note there is a minimum it can be). See our blog item that explains headrail allowances.
Roman Blind Headrail Allowance Explained
I have 2 window one with 148cm drop and the other with 87cm drop. For the first window I have made the blind with 5 rod pockets (26cm spacing between pockets. should I make the smaller blind with 1 or 2 rod pockets
We would try to make them so they are the same or a very similar depth when pulled up.
Thanks so much for the superb calculator - just save me from a lot of thinking!
I have just finished a blind using your measurements and it is practically perfect.
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
Hi, Can you tell me if I can raise my roman blinds higher by putting another hook on the wooden batten. Someone said this would pull them up even further but I can't find any information about this?
Thanks
Anne
No
When the blind is pulled all the way up the rings on the rods pull up tight against the eyelets or headrail so it will pull up no further. Adding a hook will make no difference. The only way to make your blind pull up higher would be to remake it with more rods spaced closer together and a shorter headrail allowance.
The depth of the blind when pulled up is one of your main considerations when you decide the headrail allowance, number of rods and fold depth you are going to use at the start of the making process.
My window is 60cm wide with 55cm drop
Would a Roman blind look with one fold? I am guessing that my drop is too small for 2 folds
I have Roman blind on the other 2 windows in the room and unsure what to do with this window
Thanks for any advise
If it is inside the recess we would probably go for 2 rod pockets, so not too much light is being blocked out when the blind is up.