Measuring For Curtains – The Complete “Do-it-Yourself” Guide

Measuring for and hanging curtains is straightforward in many situations and can be done by anyone competent in DIY (do-it-yourself).

However, there are some situations where it is advisable to employ an expert. These include:

  • Bay windows
  • Slot windows; very narrow, tall windows
  • Windows without sufficient wall space above the window for a pole/track
  • Windows without wall space or on either side
  • Non-rectangular windows (e.g. circular, triangular,)

But for most situations you will be using either a curtain track or pole across a flat rectangular window. So there are only two measurements of importance. When measuring use a sturdy metal tape measure, have a spirit level handy to check whether poles, batten, floors etc are truly level. Use proper safe steps if you are working at height and for large windows have an assistant hold the other end of the tape. The old adage “measure twice and cut once” holds true!

Measuring curtain width

Start by measuring the width of the window horizontally across the recess occupied by the window & its frame. [Note the width of a window is not the width of the glazing.] Now add 20-30cm (8-12″), on each side since the track or pole should extend beyond each side of the window to enable the curtains to be drawn well back. A large window has more fabric in the curtain and so needs more space either side to pull back completely. If there is insufficient space on either side of the window you may have to adjust your design and it would be better to get some expert assistance.

You may find a pre-existing wooden batten above the window and this should similarly extend beyond the window aperture. If it does not you may consider replacing or extending the batten. If you are fitting a track then the batten will be useful, whereas if you are fitting a pole the batten can be an obstruction. When you buy a pole make sure that the pole length (distance between finials) is equal to or greater than the required width and ensure that you can cut the pole length down to the desired size.

Measuring curtain drop

Curtain drop is the distance between the top and bottom of the fabric in the finished curtain, and it depends on the style of curtain heading, positioning of the pole or track and the position of the bottom of the curtain. When installing a curtain pole aim to position it above the window so that the top of the curtain fabric is at least 10cm / 4inches above the top of the window recess.

  • Curtain Poles with rings: As a rule the top of the curtain should be just below the rings so measure the drop from the bottom of the ring.
  • Curtain pole with eyelet curtains: In this situation there are no curtain rings and the top of the curtain will be above the pole. Measure the drop from the top of the pole and add 3.5cm to aloe for the amount of curtain that will be above the pole.
  • Curtain poles with tab top curtains measure drop from the top of the pole.

For all curtains you need to decide where the bottom will finish:

  • Sill length: the curtain should finish 1cm above the sill (but note that this will let more light into the room).
  • Below sill length; often curtains finish part way between the sill and a wall mounted radiator. Sometimes they hang over the radiator but this channels warm air up behind the curtain and so does not help keep the room warm. Decide where you want the fabric to end.
  • Full length; the curtain finishes 1.5cm above the floor. This measurement needs precision because many floors are not absolutely level. Measure the drop from an installed pole or track in three places, the centre and to the left & right. Work with the smallest measurement but double check that the track or pole is level. If in doubt check the slope of the floor.
  • Pooled; compared with full length curtains these usually have an extra 30cm /12 inches of fabric to pool onto the floor


Once you have width and drop give these figures to your curtain maker who will be able to calculate the quantity of fabric you will need and the cost of making up the curtains. You will also need to agree on the curtain heading and on the type of lining for your curtains. All this may seem hard work but you will end up with bespoke made to measure curtains that fit your window perfectly; something that factory made curtains rarely can achieve.