(LTT) If possible measure with a metal tape measure for accuracy

Is your blind going to be installed within the recess or outside recess above the window?

Measuring Outside recess fitted blinds (above window)

Decisions – Where would you like your blind to drop? (Finished length of the blind)

Finish resting on top of the sill or drop down to below the sill. (Below the sill is better for bedroom blackout blinds as you are reducing the possibility of light saturation. Below the sill would also be best if adding a trim to your blind.

However for a blind where it’s not essential to block out the light, the blind dropping to the top of the sill looks beautifully neat and elegant.

(a) Installation height to the drop of your blind (left)

(b) Installation height to the drop of your blind (right)

(c) Installation height to the drop of your blind (middle)

(d) Width of your sill (or required width for your blind if different)

Installation Height

This does depend on whether you are using a baton or track. All of my literature is based on tracks as I feel it’s important to keep blinds as safe as possible.
To put simply, it’s wherever you want the blind fitted above the window, at least the height of your baton/track. For a track, allow a minimum of 5cms. As standard a further 5cms is usually added giving you an installation 10cms above the window.

Width of your blind

I always make my outside recess blinds the same width as the sill. I just think it looks odd having the blind smaller than this with sill sticking out either side. This also removes any issues with width discrepancies across the window.