It’s approx 38cm from the ground to top of cushion, though obviously they squish down when you sit on them. (The sofa cushion is thinner than the chair cushions).
I love mine, I find it comfy, especially if I sit in the ‘corner’ and stretch out (I have it in an L shape). I’m just under 5’7. It looks nice too.
One thing I would say is the cushions aren’t particularly waterproof - well mine aren’t anyway. So I put them away at night and if it looks showery. One got wet once and took 3 days to dry out properly!