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Fabric calculations for curtains and blinds

Curtain fabric calculator

This article has been provided by soft furnishing expert Pippa Blackler. Find out more about Pippa by visiting her site http://www.pippablackerinteriors.co.uk/ 


Measuring windows and how much fabric to use

Measuring a window correctly and working out the position of fittings, is a vital part in the preparation for any window treatment. You need accurate window measurements for your curtains or blinds to help with the fabric calculations for curtains and blinds, you don’t want to find yourself a few inches short!

Fabric calculator for curtains


Take a good look at the window; try to imagine the curtains when they are finished. How will they look when they are open or closed? Consider how high the fitting can sit above the frame and where the curtains will stack back.   As a general rule a curtain fixture should be the width of the window plus stacking space.  Visualizing all this will help you work out where to place your curtain track or pole.

Measuring – With the fittings in place you are ready to work out how much fabric you need.  For curtain poles, measure from the bottom of the curtain ring to the floor, this will give you the final drop.  For the width, simply measure the working length of the curtain pole, don’t include the finial as these are just decoration.

For curtain tracks, measure from the top of the track to the floor, for the final drop.  For the width, measure the working length of the track, including any overlaps.

Fabric calculations – Most curtains will require somewhere between 1 ½ and 2 ½ times fullness, depending on the heading and look you want to achieve.  I always prefer to be generous and use 2 ½ times the width, skimpy curtains don’t look good and you can always use any extra fabric for cushions or tie backs.

Multiply the finished width of the curtain, say 150cm, by the required fullness.

Divide this by the cut width of your fabric (usually 137cm)

Round up to the nearest full number, this is how many widths you need.

Take the final drop measurement, say 200cm + 25 cm for hem allowance, + any pattern repeat and then ‘times’ by the amount of widths, this will give you how many meters you need.


Finished width 150cm
Finished drop 200cm
150 x 2.5 = 375  Divide by 137cm = 2.7 (round up to 3) 3 Widths required
200 + 25 (hem) + 20 (pattern repeat of 20cm) = 245 x 3 = 735 (round up to 750)
7.5m of fabric required to make the curtains.

roman Blind fabric calculator

Roman Blind

Again, study the window carefully and try to imagine how the Roman blind will look when it is open and closed.  The important point to remember with Roman blinds is that they will need more space at the top as they pleat rather than roll up. A Roman blind sited above the window frame will make the window look longer.   If the blind is to sit within a recess, you will lose some light because of the stack back.
Roman blinds are fitted to the wall or recess using a covered wooden batten.  This can be fitted in advance.  Make the batten 1cm shorter than the finished width of your intended blind.

Measuring – Roman blinds can be a very economical window treatment as often they only require 1 width of fabric.  Decide on the final width of the blind, measure the width several times across the area to be covered, ensuring that you consider any tiles or obstructions within the recess.  If the blind is outside the recess use the window sill as a width guide.  Also remember to look carefully at window handles, latches and cornicing, these can get in the way and may dictate where you position the blind and how wide or long it can be.  For the length, measure from the top position of the blind to just below the window sill or just sitting onto the sill, if in a recess.

Fabric calculations – Take your final width measurement, say 120cm and add 10cm for your side seams.
Take your final length measurement, say 160cm and add 15cm for hem/heading and 15cm for covering your batten. Always add the pattern repeat too, even if you are not joining widths, this will allow you to position the pattern to the best effect.


120 + 10 = 130cm (fits within 137cm standard width)
160 + 15 + 15 + 20 (pattern repeat) = length 210cm (round up to the nearest quarter metre 2.25m)
2.25m of fabric required to make the blind.

This is a simple guide to measuring – no two windows are ever the same, particularly in old houses, often the windows are not straight either!  Always use a good quality retractable tape measure. Take all your measurements… and then measure everything again!

Happy decorating!

Contact: Pippa Blacker 07790 81 31 91
Order fabrics for your own projects:  http://www.pippablackerinteriors.co.uk/ 
You can also follow me on Twitter.

For buying soft furnishing fabrics online take a look at the Yorkshire Fabric Shop, Terry’s Fabrics or Plumb’s Marketplace.

You might like our Simple Pencil Pleat Curtain tutorial or Interlined Triple Pleat Curtain tutorial.