Dunk Calculator - How High Do You Need to Jump?
Enter your height and this calculator works out the vertical jump you need to dunk, touch the rim, or throw down a flashy windmill. If you know your standing reach, enter it directly for a more precise result. You also get hang time, takeoff velocity, and a breakdown of how the numbers add up. Switch freely between metric and imperial units.
How the dunk calculator works
The core formula is simple: Required vertical jump = (rim height + clearance above rim) minus your standing reach. Standing reach is how high your fingertips are when you stand flat-footed with one arm extended straight overhead. Most people have a standing reach of about 1.33 times their height, but the ratio varies by arm length. If you know your exact reach, entering it gives a more precise answer. The default rim height is 10 feet (120 inches), which is the standard for NBA, FIBA, and high-school play. Youth leagues commonly use 8-foot or 9-foot rims, and you can change the rim height to match wherever you play.
Clearance above the rim and what it means
You cannot dunk by simply reaching the rim with your fingertips - your wrist (or at least two or three fingers) needs to clear the rim for a legal dunk. Six inches of clearance is the commonly cited coaching benchmark for a controlled one-hand dunk. More clearance lets you hang longer, switch hands, or go for a more powerful two-hand slam. The windmill preset uses 12 inches, matching the rough aerial hang needed for a full-rotation finish. Adjust the clearance field down to 0 if you only want to know how high you must jump to touch the rim, or up to 10 or 12 inches for a more aggressive target.
Hang time and takeoff velocity
Hang time is determined by the height of your jump using the projectile-motion formula t = 2 x sqrt(2h / g), where h is the vertical height in metres and g is 9.807 m/s squared. A 24-inch vertical gives about 0.70 s of total air time; a 36-inch vertical extends that to about 0.86 s. Michael Jordan was estimated to have a hang time around 0.92 s, corresponding to a vertical near 42 inches. Effective hang time is the portion of the jump spent above the rim, which is shorter than total hang time but is what matters for getting the ball through the hoop. Takeoff velocity is the initial upward speed your legs must produce, calculated as v = sqrt(2gh).
How to improve your vertical jump
The most effective methods for increasing your vertical are plyometric exercises (depth jumps, box jumps, broad jumps), heavy lower-body strength work (squats, deadlifts, single-leg presses), hip-flexor and ankle mobility work, and sprint-based conditioning for fast-twitch activation. Research consistently shows that combining max-strength training with explosive plyometrics outperforms either alone. Eight to twelve weeks of consistent training can realistically add 3 to 6 inches to most untrained athletes, and more for those who start with notable weaknesses in hip extension or ankle stiffness. Approach footwork matters too: a running two-step gather into the jump typically adds 4 to 8 inches compared with a standing vertical, which is why most professional dunkers use a one-foot or two-foot gather.
Vertical jump needed to dunk by height (standard 10 ft rim)
| Height | Est. standing reach | Vertical to touch rim | Vertical to dunk |
|---|---|---|---|
| 5'4" (64 in) | 85 in | 35 in | 41 in |
| 5'6" (66 in) | 88 in | 32 in | 38 in |
| 5'8" (68 in) | 90 in | 30 in | 36 in |
| 5'10" (70 in) | 93 in | 27 in | 33 in |
| 6'0" (72 in) | 96 in | 24 in | 30 in |
| 6'2" (74 in) | 98 in | 22 in | 28 in |
| 6'4" (76 in) | 101 in | 19 in | 25 in |
| 6'6" (78 in) | 104 in | 16 in | 22 in |
Assumes a standing reach of 1.33x height and 6 inches of clearance above the rim. Taller players need less vertical because their reach is closer to the rim.
Frequently asked questions
What is the minimum vertical jump to dunk on a 10-foot rim?
It depends entirely on your standing reach. A 6-foot player with an average standing reach of about 96 inches needs roughly 30 inches of vertical to dunk with 6 inches of clearance. A 6-foot-4 player with a longer reach might need only 25 inches. Use the calculator above with your actual height or standing reach for your personal number.
What is standing reach and how do I measure it?
Standing reach is the height of your fingertips when you stand flat on the floor with your dominant arm extended straight overhead. Stand against a wall, reach as high as you can without tiptoeing, and mark the wall or have someone read a measuring tape. Most people have a reach of about 1.33 times their height, but arm length varies enough that measuring directly is worth it.
Does a running jump add to my vertical?
Yes, significantly. A running one-step or two-step gather typically adds 4 to 8 inches over a standing vertical for most athletes. The calculator uses your vertical as a fixed input; if you are using your standing vertical test number, your actual dunking vertical in a game approach will be higher. Many players who cannot dunk off a standing jump can dunk easily off a full run.
How is hang time calculated?
Hang time follows standard projectile motion: t = 2 x sqrt(2h / g), where h is the jump height in metres and g is 9.807 m/s squared. The "2" doubles the time of the upward half (which mirrors the downward half by symmetry). A 30-inch vertical (0.762 m) gives about 0.787 seconds of total hang time. Effective hang time above the rim is a shorter window within that.
Can someone who is 5 foot 6 dunk?
Yes, but it requires an elite vertical. A 5-foot-6 player has an estimated standing reach around 88 inches and needs about 38 inches of vertical to dunk with 6 inches of clearance. That is above the NBA average (28 to 30 inches) but has been achieved by athletes such as Spud Webb (5 ft 7), who had a measured vertical over 40 inches. It requires years of serious jump training.
What clearance above the rim do I need to actually dunk?
Coaches and trainers typically recommend at least 6 inches of wrist-to-rim clearance for a controlled dunk - enough to grip the ball and get it cleanly through the hoop. If you aim for only 1 or 2 inches, you may clip the rim or lose control of the ball. For training purposes, targeting 8 or 9 inches gives a comfortable margin.
What was Michael Jordan's vertical jump?
Michael Jordan's maximum vertical jump has been reported at approximately 48 inches, though official pre-draft measurements and in-season estimates vary. His commonly cited vertical for dunking was around 45 inches, with a hang time estimated at roughly 0.92 seconds. These are extraordinary figures; the NBA average is around 28 inches.