The ounce is a fascinating unit with a rich history, dating back to Ancient Rome. The term “ounce” is derived from the Latin word “uncia,” meaning “one-twelfth.” Originally used by the Romans as a unit of weight, an uncia represented one-twelfth of a Roman pound. The versatility of the ounce becomes even more intriguing when you consider its application in both weight and volume measurements today.
In the realm of precious metals, such as gold and silver, the term “troy ounce” is used, which is approximately 10% heavier than the customary ounce. Meanwhile, in British imperial and American systems, an ounce can denote both dry and liquid measurements. The fluid ounce, however, differs slightly between the UK and the US, with the UK fluid ounce being approximately 28.4 milliliters and the US at about 29.6 milliliters. This multifaceted unit highlights how historical roots continue to influence modern measurement systems worldwide.
The kilogram, the base unit of mass in the International System of Units (SI), has a fascinating history tied to a physical artifact. Until 2019, it was defined by Le Grand K, a platinum-iridium cylinder stored in a vault in France. However, even slight surface contamination or material wear could alter its mass. To ensure a more stable and universally consistent measure, the kilogram is now defined by the Planck constant—a fundamental constant of nature—using a Kibble balance. This revolutionary change marked a significant milestone in metrology and brings mass measurement into line with other SI units that are already defined by fundamental constants, rather than physical objects.
| Ounces | Kilograms |
|---|---|
0
oz
|
0
kg
|
1
oz
|
0.0283495
kg
|
2
oz
|
0.056699
kg
|
3
oz
|
0.0850486
kg
|
4
oz
|
0.113398
kg
|
5
oz
|
0.141748
kg
|
6
oz
|
0.170097
kg
|
7
oz
|
0.198447
kg
|
8
oz
|
0.226796
kg
|
9
oz
|
0.255146
kg
|
10
oz
|
0.283495
kg
|
11
oz
|
0.311845
kg
|
12
oz
|
0.340194
kg
|
13
oz
|
0.368544
kg
|
14
oz
|
0.396893
kg
|
15
oz
|
0.425243
kg
|
16
oz
|
0.453592
kg
|
17
oz
|
0.481942
kg
|
18
oz
|
0.510291
kg
|
19
oz
|
0.538641
kg
|
20
oz
|
0.56699
kg
|
21
oz
|
0.59534
kg
|
22
oz
|
0.62369
kg
|
23
oz
|
0.652039
kg
|
24
oz
|
0.680389
kg
|
25
oz
|
0.708738
kg
|
26
oz
|
0.737088
kg
|
27
oz
|
0.765437
kg
|
28
oz
|
0.793787
kg
|
29
oz
|
0.822136
kg
|
30
oz
|
0.850486
kg
|
31
oz
|
0.878835
kg
|
32
oz
|
0.907185
kg
|
33
oz
|
0.935534
kg
|
34
oz
|
0.963884
kg
|
35
oz
|
0.992233
kg
|
36
oz
|
1.02058
kg
|
37
oz
|
1.04893
kg
|
38
oz
|
1.07728
kg
|
39
oz
|
1.10563
kg
|
40
oz
|
1.13398
kg
|
41
oz
|
1.16233
kg
|
42
oz
|
1.19068
kg
|
43
oz
|
1.21903
kg
|
44
oz
|
1.24738
kg
|
45
oz
|
1.27573
kg
|
46
oz
|
1.30408
kg
|
47
oz
|
1.33243
kg
|
48
oz
|
1.36078
kg
|
49
oz
|
1.38913
kg
|
50
oz
|
1.41748
kg
|
51
oz
|
1.44583
kg
|
52
oz
|
1.47418
kg
|
53
oz
|
1.50252
kg
|
54
oz
|
1.53087
kg
|
55
oz
|
1.55922
kg
|
56
oz
|
1.58757
kg
|
57
oz
|
1.61592
kg
|
58
oz
|
1.64427
kg
|
59
oz
|
1.67262
kg
|
60
oz
|
1.70097
kg
|
61
oz
|
1.72932
kg
|
62
oz
|
1.75767
kg
|
63
oz
|
1.78602
kg
|
64
oz
|
1.81437
kg
|
65
oz
|
1.84272
kg
|
66
oz
|
1.87107
kg
|
67
oz
|
1.89942
kg
|
68
oz
|
1.92777
kg
|
69
oz
|
1.95612
kg
|
70
oz
|
1.98447
kg
|
71
oz
|
2.01282
kg
|
72
oz
|
2.04117
kg
|
73
oz
|
2.06952
kg
|
74
oz
|
2.09786
kg
|
75
oz
|
2.12621
kg
|
76
oz
|
2.15456
kg
|
77
oz
|
2.18291
kg
|
78
oz
|
2.21126
kg
|
79
oz
|
2.23961
kg
|
80
oz
|
2.26796
kg
|
81
oz
|
2.29631
kg
|
82
oz
|
2.32466
kg
|
83
oz
|
2.35301
kg
|
84
oz
|
2.38136
kg
|
85
oz
|
2.40971
kg
|
86
oz
|
2.43806
kg
|
87
oz
|
2.46641
kg
|
88
oz
|
2.49476
kg
|
89
oz
|
2.52311
kg
|
90
oz
|
2.55146
kg
|
91
oz
|
2.57981
kg
|
92
oz
|
2.60816
kg
|
93
oz
|
2.63651
kg
|
94
oz
|
2.66486
kg
|
95
oz
|
2.6932
kg
|
96
oz
|
2.72155
kg
|
97
oz
|
2.7499
kg
|
98
oz
|
2.77825
kg
|
99
oz
|
2.8066
kg
|
100
oz
|
2.83495
kg
|
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