The benefits of working out at home include convenience, privacy and the freedom to work out how and when you want. Available space is the main obstacle that keeps many lifters commuting to and from commercial fitness centers. Workout equipment takes up space, sometimes a lot of space, which not everyone has the luxury of giving up. However, you don't need a large universal gym to work out at home; a bench and some dumbbells will get you started, and they don't require as much space as you might think.
Weight benches are available in a variety of sizes and types. Most benches are 15 to 19 inches wide, but it is the length that takes up the most space. At 45 to 50 inches in length, nonadjustable flat benches are shorter than their adjustable counterparts, which are typically 50 to 55 inches long. But nonadjustable benches limit your workout and exercise options. The extra functionality of an adjustable bench is well worth the extra inches it takes up. Benches with attached leg extension pads, curl equipment or a barbell rack require considerably more space and are not necessary for an effective workout.
A weight bench doesn't take up a lot of space, but you don't need room for just the bench -- you also need room to move around and perform a variety of exercises. Plan for several feet of open space around the bench, two to three feet on each side and a couple of feet on each end. Adding in the size of the bench itself, you will need an open area six to eight feet wide and eight to 10 feet long.
If you don't have a dedicated space for your home gym, consider using a folding bench. They are more expensive than their solid counterparts, but you can fold them up when you are not working out to open up the space. Weight benches are typically 15 to 20 inches tall. A folding bench collapses to about half its original height, so you can lean it against a wall, put it in a closet, or slide it under a bed.
Besides a bench, you'll also need some dumbbells. The American Council on Exercise estimates you will need 20 to 50 square feet of space for free weights. Eventually, you may want other equipment, such as a barbell and power rack, which requires significantly more space: 35 to 50 square feet. If you choose to include aerobic equipment, such as a treadmill or elliptical machine, you will need another 10 to 30 square feet per machine.