An adjustable wheelchair for ready assembly in accordance with embodiments of the invention are disclosed. In one embodiment, the wheelchair includes, an undercarriage including, a horizontal axle including a first end segment telescopically coupled to a body segment and a second end segment telescopically coupled to the body segment opposite the first end segment allowing for adjustment of the wheelchair width, and a tongue including a body segment telescopically coupled to an end segment allowing for adjustment of the wheelchair length, and a seat post including an end segment telescopically coupled to a body segment allowing for adjusting the wheelchair seat height and a pair of wheels and a swivel wheel coupled to the tongue of the undercarriage to support the wheelchair and provide mobility and a seat bottom coupled to the end segment of the seat post for load-bearing support and a seatback rotatably coupled to the seat bottom.
