Can I dunk a basketball?
Enter your standing reach and, if you know it, your vertical jump. The dunk calculator shows how high you must jump to dunk on a 10-foot rim and whether you can.
- Vertical jump needed (in)
- 30
With a standing reach of 96 in, you need a vertical jump of 30 in (76.2 cm) to dunk on a 120 in rim.
- Vertical jump needed (cm)cm
- 76.2
- Can you dunk?
- No
- Your jump minus the jump neededin
- -4
- Your jump minus the jump needed (cm)cm
- -10.2
- Your reach at the top of the jumpin
- 122
- Your reach at the top of the jump (cm)cm
- 309.9
- Take-off speed needed
- 8.65 mph
- Hang time of that jump
- 0.788 s
Vertical jump needed (in): 30. With a standing reach of 96 in, you need a vertical jump of 30 in (76.2 cm) to dunk on a 120 in rim.
Vertical jump needed (in) by standing reach
How to calculate
Computes the vertical jump you need to dunk a basketball from your standing reach, the rim height and how far above the rim your hand must reach, and says whether your vertical jump is enough.
Example with the default inputs (Standing reach 96 in, Your vertical jump 26 in, Rim height 120 in, Reach above the rim 6 in): With a standing reach of 96 in, you need a vertical jump of 30 in (76.2 cm) to dunk on a 120 in rim.
Method: vertical jump needed = rim height + reach above the rim − standing reach (0 if negative); take-off speed = √(2 × g × jump); hang time = 2 × √(2 × jump ÷ g), g = 9.80665 m/s².
- The reach above the rim is how high over the rim your fingertips must get to push the ball down through it. 6 inches is a common rule of thumb for a one-hand dunk; people with small hands, or who dunk with two hands, need more. Change it to suit you.
- Standing reach and vertical jump are measured as on a vertical jump test: flat-footed reach with one arm, then the extra height touched at the top of a jump.
- Take-off speed and hang time use projectile motion with no air resistance and standard gravity, g = 9.80665 m/s².
- Lengths are added and subtracted exactly as typed; values are rounded only for display.
Worked examples
Each example is checked against the calculator on every build.
- Standing reach 96 in, Your vertical jump 26 in, Rim height 120 in, Reach above the rim 6 in gives Vertical jump needed (in) 30, Vertical jump needed (cm) 76.2, Can you dunk? no, Your jump minus the jump needed -4, Your jump minus the jump needed (cm) -10.16, Your reach at the top of the jump 122, Your reach at the top of the jump (cm) 309.88, Take-off speed needed 8.65 mph, Hang time of that jump 0.788 s.Source: NBA Official Rule No. 1, Section II (the rim is 10 feet above the floor), https://official.nba.com/rule-no-1-court-dimensions-equipment/
- Standing reach 90 in, Rim height 120 in, Reach above the rim 6 in gives Vertical jump needed (in) 36, Vertical jump needed (cm) 91.44.Source: 120 + 6 − 90 = 36 in (rim height from NBA Official Rule No. 1, https://official.nba.com/rule-no-1-court-dimensions-equipment/)
- Standing reach 106.3 in, Your vertical jump 23.62 in, Rim height 120.1 in, Reach above the rim 5.906 in gives Vertical jump needed (in) 19.685039, Vertical jump needed (cm) 50, Can you dunk? yes, Your jump minus the jump needed 3.937008, Your jump minus the jump needed (cm) 10, Your reach at the top of the jump (cm) 330, Take-off speed needed 7.01 mph, Hang time of that jump 0.639 s.Source: FIBA Official Basketball Rules 2024, Basketball Equipment (the ring is 3,050 mm above the floor)
- Standing reach 98.43 in, Your vertical jump 0 in, Rim height 84 in, Reach above the rim 6 in gives Vertical jump needed (in) 0, Vertical jump needed (cm) 0, Can you dunk? yes, Your jump minus the jump needed 0, Take-off speed needed 0 mph, Hang time of that jump 0 s.
How it works
To dunk, the top of your jump must put your hand a little above the rim. So the vertical jump you need is
jump needed = rim height + reach above the rim − standing reach
If that is below 0, you reach high enough standing, and the jump needed is 0.
With your vertical jump:
- your reach at the top of the jump = standing reach + vertical jump
- your jump minus the jump needed = vertical jump − jump needed
- you can dunk (Yes) when your vertical jump is at least the jump needed, else No.
For the jump needed h (in metres), with standard gravity g = 9.80665 m/s² and no air resistance:
- take-off speed = √(2 × g × h)
- hang time = 2 × √(2 × h ÷ g), the time up plus the time down
Inputs and rules
- Standing reach: 0.5 m to 3.5 m. Your vertical jump (optional): 0 to 2 m. Rim height: 1 m to 4 m (10 ft by default). Reach above the rim: 0 to 0.6 m (6 in by default).
- Lengths can be typed in inches, feet, feet and inches, centimetres or metres.
What the calculator shows
- Each length box is read as the exact decimal you typed in its unit (305 cm is exactly 3.05 m; 10 ft is exactly 3.048 m; 8 ft 2 in is 8 × 0.3048 + 2 × 0.0254 m), and the lengths are added and subtracted exactly. "Can you dunk?" is Yes exactly when your vertical jump ≥ the jump needed.
- Vertical jump needed, Your jump minus the jump needed and Your reach at the top of the jump: each in inches (the exact metres ÷ 0.0254) and in centimetres (× 100), each rounded half up from its exact value to at most one decimal place (trailing zeros are not shown: 30, not 30.0).
- Take-off speed in miles per hour (km/h in Metric), to at most two decimal places.
- Hang time in seconds, to at most three decimal places.
- Without your vertical jump, only the jump needed, take-off speed and hang time.
Worked examples by hand
Standing reach 8 ft, a 26 in vertical, a 10 ft rim, 6 in above the rim. Jump needed = 120 + 6 − 96 = 30 in (0.762 m, 76.2 cm). Your reach at the top: 96 + 26 = 122 in (309.88 cm, shown 309.9). Your jump minus the jump needed: 26 − 30 = −4 in (−10.16 cm, shown −10.2), so No: you need 4 more inches. Take-off speed: √(2 × 9.80665 × 0.762) = 3.8659 m/s = 8.65 mph. Hang time: 2 × √(2 × 0.762 ÷ 9.80665) = 0.788 s.
Standing reach 7 ft 6 in. Jump needed = 120 + 6 − 90 = 36 in (91.44 cm, shown 91.4).
Metric: a 2.70 m reach and a 60 cm vertical at a 3.05 m ring, 15 cm above the ring. Jump needed = 3.05 + 0.15 − 2.70 = 0.50 m = 50 cm = 19.685 in (shown 19.7). Your jump minus the jump needed: 0.60 − 0.50 = 0.10 m = 10 cm, so Yes. Take-off speed: √(2 × 9.80665 × 0.5) = 3.1316 m/s. Hang time: 2 × √(1 ÷ 9.80665) = 0.639 s.
A 7 ft kids’ hoop with a 2.5 m reach. 2.1336 + 0.1524 − 2.5 = −0.214 m, below 0, so the jump needed is 0: you can dunk standing.
Other questions people ask
How high do I need to jump to dunk?
Take the rim height, add how far above the rim your hand must reach, and subtract your standing reach. With a standing reach of 8 feet (96 inches), a 10-foot rim (120 inches) and 6 inches above the rim: 120 + 6 − 96 = 30 inches of vertical jump.
How do I measure my standing reach?
Stand flat-footed next to a wall, stretch one arm straight up and mark the highest point your fingertips touch. The height of that mark is your standing reach. Measure it rather than guess from your height: arm length varies a lot between people of the same height.
How do I measure my vertical jump?
Jump from a standstill next to the same wall and touch as high as you can. Your vertical jump is the height of that touch minus your standing reach. Take the best of three tries.
How far above the rim do I need to reach to dunk?
The calculator uses 6 inches as a starting point. You need enough height to hold the ball above the rim and push it down through, so people with small hands, or who dunk with two hands, need more. Change Reach above the rim to suit you.
How high is a basketball rim?
A regulation rim is 10 feet (3.05 m) above the floor in the NBA, college, high school and FIBA play. Youth hoops are often lower, for example 8 or 9 feet; enter the height of the hoop you play on.
What do take-off speed and hang time mean?
They describe the jump you need. Take-off speed is how fast you must leave the floor to rise that high, √(2 × g × height). Hang time is how long that jump keeps you in the air, up and down, 2 × √(2 × height ÷ g). A 30-inch jump needs about 8.65 mph at take-off and lasts about 0.79 seconds.