Server Rack Sizes “U” in “22U” is stands for “rack units,” or “U-spaces,” which equal 1.75 inches.
| Rack Units | Height (in) | Height (ft) | Height (cm) |
| 1U | 1.75″ | 0.15′ | 4.4 cm |
| 2U | 3.5″ | 0.29′ | 8.9 cm |
| 3U | 5.25″ | 0.44′ | 13.3 cm |
| 4U | 7″ | 0.58′ | 17.8 cm |
| 5U | 8.75″ | 0.73′ | 22.2 cm |
| 6U | 10.5″ | 0.88′ | 26.7 cm |
| 7U | 12.25″ | 1.02′ | 31.1 cm |
| 8U | 14″ | 1.17′ | 35.6 cm |
| 9U | 15.75″ | 1.31′ | 40 cm |
| 10U | 17.5″ | 1.46′ | 44.5 cm |
| 11U | 19.25″ | 1.6′ | 48.9 cm |
| 12U | 21″ | 1.75′ | 53.3 cm |
| 13U | 22.75″ | 1.9′ | 57.8 cm |
| 14U | 24.5″ | 2.04′ | 62.2 cm |
| 15U | 26.25″ | 2.19′ | 66.7 cm |
| 16U | 28″ | 2.33′ | 71.1 cm |
| 17U | 29.75″ | 2.48′ | 75.6 cm |
| 18U | 31.5″ | 2.63′ | 80 cm |
| 19U | 33.25″ | 2.77′ | 84.5 cm |
| 20U | 35″ | 2.92′ | 88.9 cm |
| 21U | 36.75″ | 3.06′ | 93.3 cm |
| 22U | 38.5″ | 3.21′ | 97.8 cm |
| 23U | 40.25″ | 3.35′ | 102.2 cm |
| 24U | 42″ | 3.5′ | 106.7 cm |
| 25U | 43.75″ | 3.65′ | 111.1 cm |
| 26U | 45.5″ | 3.79′ | 115.6 cm |
| 27U | 47.25″ | 3.94′ | 120 cm |
| 28U | 49″ | 4.08′ | 124.5 cm |
| 29U | 50.75″ | 4.23′ | 128.9 cm |
| 30U | 52.5″ | 4.38′ | 133.4 cm |
| 31U | 54.25″ | 4.52′ | 137.8 cm |
| 32U | 56″ | 4.67′ | 142.2 cm |
| 33U | 57.75″ | 4.81′ | 146.7 cm |
| 34U | 59.5″ | 4.96′ | 151.1 cm |
| 35U | 61.25″ | 5.1′ | 155.6 cm |
| 36U | 63″ | 5.25′ | 160 cm |
| 37U | 64.75″ | 5.4′ | 164.5 cm |
| 38U | 66.5″ | 5.54′ | 168.9 cm |
| 39U | 68.25″ | 5.69′ | 173.4 cm |
| 40U | 70″ | 5.83′ | 177.8 cm |
| 41U | 71.75″ | 5.98′ | 182.2 cm |
| 42U | 73.5″ | 6.13′ | 186.7 cm |
| 43U | 75.25″ | 6.27′ | 191.1 cm |
| 44U | 77″ | 6.42′ | 195.6 cm |
| 45U | 78.75″ | 6.56′ | 200 cm |
| 46U | 80.5″ | 6.71′ | 204.5 cm |
| 47U | 82.25″ | 6.85′ | 208.9 cm |
| 48U | 84″ | 7′ | 213.4 cm |