Jumping is the Key
Basically, jumping is power. Power, on the other hand, is a rate at which a certain action can be performed. Therefore, in order to increase your vertical jump, you need to increase your force output, the distance which you are covering while releasing the force and the time necessary for this action to happen.
The following exercises will help you boost all of the three vertical jump factors mentioned above.
Exercises for Increasing your Vertical Jump
Squats are one of the best exercises for these purposes, since they resemble jumping. When you perform squats, make sure you go as low as possible, activating your glute muscles. Once you become more skilled in squats, do them while standing on a single leg. Sometimes, vertical jumping needs to be performed off a single leg. So, this type of squats will improve this action.
When doing squats, focus on carrying up to 1.5 times your body weight. When you find yourself capable of doing this, your vertical jump is bound to get improved. Also, when doing your squats, focus on pushing your body outwards, boosting your explosive phases of the vertical jump.
Once you are almost in the air, your calf muscles make the final propulsion. Therefore, you need to improve these muscles too. For this purpose, do calf raises off a step, with the maximum range of motion possible.
Alternatively, you can use a barbell or a set of dumbbells during this exercise, holding them across your back. Three sets of up to 25 repetitions will be enough.
Finally, you are advised to improve your body's flexibility through exercises for your quads, hamstrings, hip flexors and calves.