The amount of space you will need will depend on the size of the person using the reformer. You will need enough space for the reformer itself, and for the user’s limbs to fully extend outward when using it.
The standard recommended clearance for a reformer is 4-5 feet in width per unit.
To ensure you have enough space for your equipment, measure the dimensions of the room you intend to keep your equipment in. Then, compare this to the product’s dimensions which can be found in its description.