thumb|200px|A diagram of various units derived from the human hand. The palm (3) was originally the width of the palm but was standardized as the somewhat smaller width of four [[Digit (unit)|digits (6). The related shaftment (1) and hand (2) were the width of the palm plus an open or closed thumb. The other units are the span (4) and finger (5).]]
The palm is an obsolete anthropic unit of length, originally based on the width of the human palm and then variously standardized. The same name is also used for a second, rather larger unit based on the length of the human hand.
The width of the palm was a traditional unit in Ancient Egypt, Israel, Greece, and Rome and in medieval England, where it was also known as the hand, in the Papal States, the Roman palm about according to Hutton but divided into the Roman "architect's palm" (') of about and "merchant's palm" (') of about according to Greaves;
|-
| Florence (for silk, Palaiseau p.146) || align="right" | 131.63 || align="right" | [297] mm ||
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| Florence (for wool, Palaiseau p.146) || align="right" | 128.38 || align="right" | 289.6 mm ||
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| Genoa (cloth measure, Palaiseau p.148) || align="right" | 106.9 || align="right" | 241.1 mm ||
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| Genoa (linear measure, Palaiseau p.91) || align="right" | 107.43 || align="right" | 242.3 mm ||
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| Genoa (Rose) || || align="right" | 247 mm || align="right" | 9.72
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| Livorno (for silk, Palaiseau p.157)|| align="right" | 128.41 || align="right" | 289.7 mm ||
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| Livorno (for wool, Palaiseau p.157)|| align="right" | 130.08 || align="right" | 293.4 mm ||
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| Malta (cloth measure, Palaiseau p.160) || align="right" | 114.49 || align="right" | 258.3 mm ||
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| Malta (linear measure, Palaiseau p.98) || align="right" | 115.28 || align="right" | 260.0 mm ||
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| Naples (Rose) || || align="right" | 263.6 mm || align="right" | 10.38
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| Palermo (cloth measure, Palaiseau p.168) || align="right" | 107.16 || align="right" | 241.7 mm || align="right" | 9.53
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| Portugal (Palaiseau p.109) || align="right" | 96.36 || align="right" | 217.4 mm || align="right" | 8.64
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| Rome (cloth measure, Palaiseau p.173) || align="right" | 109.52 || align="right" | 247.1 mm ||
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| Rome (linear measure, Palaiseau p.111) || align="right" | 99 || align="right" | [223] mm ||
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| Sardinia (Rose) || || align="right" | 248 mm || align="right" | 9.78
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| Spain (Rose) || || align="right" | 219 mm || align="right" | 8.64
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| colspan=4 style= "font-size:smaller" | Metric equivalents from Palaiseau here rounded to 0.1 mm
|}
From 19th C. Italian sources emerges that :
- the ancient Venetian palm, five of which made a passo (pace), was equivalent to 0.3774 metres.
- the Neapolitan palm = 0.26333670 metres (from 1480 to 1840)
- the Neapolitan palm = 0.26455026455 metres (according to the law of 6 April 1840)
which differs from previously cited palm measure equivalents in metres above.
England
thumb|right|200px|The English palm as the width of four fingers.
The English palm, handbreadth, or handsbreadth is three inches