What this calculator does
The vertical leap needed to dunk is the rim height less your standing reach, plus enough clearance to get the ball over. A 6 inch clearance is about right for a one-handed dunk where the ball is palmed.
Standing reach matters far more than height, and it is what people get wrong when estimating. Two players of the same height can differ by several inches in reach depending on arm length and shoulder mobility, which is several inches of vertical leap they do not have to find.
The formula
The vertical leap required is the rim height minus the standing reach, plus the clearance needed to bring the ball over the rim. All three are entered in feet, and the result is given in feet, inches and centimetres. The calculation ignores the fact that reaching the rim and dunking cleanly are not quite the same thing.
| Term | Meaning |
|---|---|
| Standing reach | Fingertips to floor with one arm fully extended overhead while standing flat-footed. |
| Rim height | 10 feet for a regulation basket, and the default here. |
| Clearance | Extra height needed to get the ball over the rim, around 6 inches for a one-handed palm dunk. |
| Vertical leap | Height jumped from a standing or running start, measured as the difference between standing and jumping reach. |
The inputs explained
| Field | What to enter |
|---|---|
| Rim height (ft) | Rim height in feet. 10 is regulation. |
| Standing reach (ft) | Standing reach in feet, fingertips to floor with one arm extended overhead. |
| Clearance needed to palm/dunk the ball (ft) | Clearance needed above the rim in feet. 0.5 is six inches, which suits a one-handed dunk with the ball palmed. |
When to use it
Setting a training target
Knowing the gap between your current vertical and the required one turns a vague ambition into a specific number to work towards.
Understanding why reach matters
Adding a few inches of standing reach through better shoulder mobility removes the same few inches from the jump requirement.
Adjusting for a lower rim
Many outdoor and youth courts are below regulation height, and entering the actual rim height gives an honest figure.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much vertical leap does each standing reach need?
A regulation rim with a range of standing reaches.
| Standing reach | Vertical leap needed | In inches | In centimetres |
|---|---|---|---|
| 7.5 ft | 3.00 ft | 36.0 in | 91 cm |
| 8 ft | 2.50 ft | 30.0 in | 76 cm |
| 8.5 ft | 2.00 ft | 24.0 in | 61 cm |
| 9 ft | 1.50 ft | 18.0 in | 46 cm |
Questions
How high do I need to jump to dunk?
It depends almost entirely on your standing reach. With a 9 foot reach you need about 18 inches for a clean one-handed dunk on a regulation rim; with a 7.5 foot reach you need about 36. Height alone does not answer it, which is why reach is the input.
How do I measure my standing reach?
Stand flat-footed against a wall, extend one arm straight up as high as possible, and mark the fingertips. Measure from the floor. Do not go up on your toes, and do not use both arms, since a one-arm reach is what a dunk actually uses.
How much clearance do I need?
About 6 inches for a one-handed dunk where the ball is palmed and brought over the rim. A two-handed dunk needs noticeably more, since both hands must clear. Just touching the rim needs none at all, which is why rim-grazing is far easier than dunking.
Is a running vertical higher than a standing one?
Usually by several inches, since the approach converts horizontal momentum into vertical lift. Most dunk attempts use a running start off one foot. If you are measuring against a standing vertical, the real requirement is a little easier than it appears.
For reach relative to height, see the ape index calculator. For shooting efficiency, see the true shooting percentage calculator.