A rough idea of size and setting gets you a much closer first price. You don’t need exact figures.
For a pool fence, pace out the length of the fence line and count the gates. Tell us what the glass will fix into, such as pavers, a concrete slab, lawn or a timber deck, and whether the ground is flat or steps down.
For a balustrade, give us the length, which level it’s on, and if it runs along a balcony, a deck or a stair. Say what the floor edge is made of, and roughly how far the drop is.
For a splashback or shower screen, the width and height are enough to start, plus where any power points, windows or taps sit.
If you can, take a few photos of the area from different angles, including any slope, and have them ready when we get in touch. They save a lot of back and forth.