How do I measure roller blinds?

[SandyShores99]

I'm in rented and have the most ugly blinds throughout the house that I plan on storing in case I move. I want to buy new ones but am not sure how to measure them. Are the fittings universal? Feeling a bit daft staring at my blinds right now and not knowing where to start!

Usually it’ll tell you wherever you’re buying from how to measure?

cheap and easy - argos! Measure this inside of the frame - not the window the frame around it (the wall)

blinds to go are also really good.

both super easy to install.