The USB 3.1 specification contains a table of wire thickness versus length:
11.4.7 Wire Gauge Table
Table 11-3 is a table of VBUS/Gnd wire gauges showing the relationship between gauge and maximum length in order to achieve the previously cited voltage drop values. The user should note that these lengths are the maximum length possible to meet the voltage drop budget, thus gauges smaller and lengths greater than the table values will fail to deliver the expected voltage value.
Table 11-3. VBUS /Gnd Wire Gauge vs. Maximum Length
American Stranded Wire Gauge │ Ohms Per 100 │ Meters Maximum Cable Length
(AWG) on VBUS /Gnd │ (Maximum) │ (Meters)
28 │ 23.20 │ 0.8
26 │ 14.60 │ 1.3
24 │ 9.09 │ 2.0
22 │ 5.74 │ 3.0
20 │ 3.58 │ 5.3
It also states:
5.5.7 Cable Assembly Length
This specification does not specify cable assembly lengths. A USB 3.1 cable assembly may be of any length as long as it meets all the requirements defined in this specification. The cable assembly voltage drop budget defined in Section 11.4.2 and the cable assembly loss budget defined in Section 188.8.131.52.2, limit the cable assembly length.