it depends on their whereabouts
If the glass is below 800mm from the floor then it is deemed as a safety issue and therefore needs to be safety glass(toughened/laminated…dependant on the use) to comply with regulations…..also includes doors and anywhere within 150mm of a door….this dramatically increases the price
you also need to measure the overall thickness of the unit(outside edge to other outside edge as different frames need different thickness units
They can be anywhere from a 6mm gap to 20mm gap with 2 panes of 4-6mm glass
so if your unit is 24mm total thickness then you will need to order a unit in your length/height requirements and state that it needs to be 4/16/4 ..4mm glass,16mm gap,4mm glass etc
if the measurments are correct, I suspect that your windows are either bedroom/lounge/kitchen windows….have a measure of the floor to glass height.
sorry if this is long winded btw