As a general rule, your jump rope handles should come up somewhere between your hips and your chest when standing in the centre of your rope with one foot. If you're new to jumping, you may find it's more natural to have the rope to be slightly longer. Once you become more proficient and your form improves, you may want to shorten your rope so it just grazes the ground as you jump over it. Too much excess rope will allow for the jump rope to tangle as it hits the ground. Start with a longer rope and work your way down. It's all about what you're comfortable with! If you are just starting out, it's a good idea to go a bit longer!
Below is a sizing chart to use as reference when purchasing your jump rope.
LENGTH OF ROPE / HEIGHT OF JUMPER
7 ft for jumpers 4' to 4' 9"
8 ft for jumpers 4' 10" to 5' 3"
9 ft for jumpers 5' 4" to 5' 11"
10 ft for jumpers 6' to 6' 4"
11 ft for jumpers 6' 4" +