Between its neighbours
8 AWG has 59 % more copper than 10 AWG and 37 % less than 6 AWG. Its DC resistance is 0.778 Ω per 1000 ft at 75 °C (aluminum 1.28), and 1000 ft of it carries 50.0 lb of copper.
8 AWG wire: amps, diameter & uses
8 AWG copper is 0.1285" (3.26 mm) across and 8.37 mm², between 6 and 10 mm² metric. It is rated 40 / 50 / 55 A at 60 / 75 / 90 °C and takes a 50 A breaker. Used for 40 A ranges and cooktops, 40–50 A circuits in conduit.
01 · 1:1 wire gauge · caliper
8 AWG · bare solid copper
THIS IS:
8 AWG COPPER · 50 A BREAKER · 3.26 MM COPPER
Gauge
8 AWG
bare solid copper
Breaker
50 A
copper, max
Measured
3.26 mm
0.1285"
The gap is 3.26 mm (0.1285"), which reads as 8 AWG bare solid copper. Measure bare copper for the gauge: insulation is far thicker than the metal.
- Meets NEC 2023 Table 310.16 at 75°C — verify with your local AHJ/inspector310.16
- Drawn at true sizecalibrated screen
8 AWG
- Solid diameter
- 0.128"3.26 mm · ASTM B258 formula
- Stranded (7 strands)
- 0.146"3.71 mm · Table 8
- THHN outside
- 0.216"5.49 mm · 0.0366 in² · Table 5
- Area
- 16,510 cmil8.37 mm² · nearest IEC 10 mm²
- DC resistance, 75 °C
- 0.778 Ω/1000 ftaluminum 1.28 Ω/1000 ft · Table 8
- Copper weight
- 50.0 lb/1000 ft
Ampacity
- Copper 60 / 75 / 90 °C
- 40 / 50 / 55 ANM-B uses the 60 °C column (334.80)
- Aluminum 60 / 75 / 90 °C
- 35 / 40 / 45 A
- Largest breaker (Cu, 75 °C)
- 50 Aampacity ≥ breaker
Other gauges
- Nearest SWG
- SWG 100.128" · 3.251 mm
- IEC 60228
- 10 mm²between 6 and 10 mm²
8 AWG at a glance
Size
- Solid diameter
- 0.1285" · 3.26 mm
- Stranded (7)
- 0.146"
- THHN outside
- 0.216"
- Area
- 16,510 cmil · 8.37 mm²
- Metric
- 6 – 10 mm²
- SWG nearest
- 10 (3.251 mm)
Amps
- Copper 60/75/90 °C
- 40 / 50 / 55 A
- Aluminum 75 °C
- 40 A
- Max breaker, THHN
- 50 A
- As NM-B cable
- 40 A · black
- Ground for it
- 10 AWG
Run & fit
- 120 V at 40 A
- 57 ft at 3 %
- 240 V at 40 A
- 115 ft at 3 %
- THHN in ½" EMT
- 3
- THHN in ¾" EMT
- 6
- Copper weight
- 50.0 lb/1000 ft
8 AWG reference 22 rows
Sort any column, print a shop sheet, download CSV. Click a row to load it in the calculator.
| Actions | ||||
|---|---|---|---|---|
| 231 | 2313 | 4627 | ||
| 115 | 1156 | 2313 | ||
| 46 | 462 | 925 | ||
| 23 | 231 | 462 | ||
| 15 | 154 | 308 | ||
| 11 | 115 | 231 | ||
| 7 | 77 | 154 | ||
| 5 | 57 | 115 |
| Actions | |||||||
|---|---|---|---|---|---|---|---|
| 3 | 6 | 9 | 16 | 22 | 36 | ||
| 3 | 5 | 9 | 16 | 21 | 36 | ||
| 2 | 4 | 7 | 13 | 18 | 31 | ||
| 3 | 6 | 10 | 18 | 24 | 39 | ||
| 3 | 6 | 9 | 16 | 22 | 37 | ||
| 3 | 6 | 9 | 14 | 20 | 35 | ||
| 3 | 6 | 9 | 16 | 21 | 35 |
05 / Field guide
8 AWG
the branch-circuit size.
8 AWG copper is 0.1285" (3.26 mm) across and 8.37 mm², between 6 and 10 mm² metric. It is rated 40 / 50 / 55 A at 60 / 75 / 90 °C and takes a 50 A breaker. Used for 40 A ranges and cooktops, 40–50 A circuits in conduit.
Circuits it is used for
8 AWG is the usual choice for 40 A ranges and cooktops, 40–50 A circuits in conduit. As NM-B it comes as 8/2 and 8/3 with a black jacket, held to the 60 °C column (40 A). The equipment ground for its largest breaker is 10 AWG.
On the 1:1 gauge
The caliper above opens at 3.26 mm. Lay a stripped length along the lines and step the gauge with ← and → until the wire just fills the gap.
Questions
Answered plainly.
01How many amps can 8 AWG wire carry?
+−
8 AWG copper is rated 40 A at 60 °C, 50 A at 75 °C and 55 A at 90 °C (NEC Table 310.16, 30 °C, three conductors or fewer). Aluminum of the same size: 40 A at 75 °C.
02What size breaker for 8 AWG wire?
+−
Up to 50 A with THHN on 75 °C terminals, 40 A as NM-B cable (60 °C); the next size up is allowed by 240.4(B) only where the ampacity is not itself a standard rating.
03What is the diameter of 8 AWG wire?
+−
0.1285 inch (3.26 mm) solid, 0.146 inch stranded (7 strands), about 0.216 inch with THHN insulation.
04What is 8 AWG in mm²?
+−
8.37 mm² (16,510 circular mils). The IEC sizes either side are 6 and 10 mm²; replace it with 10 mm², not the smaller one.
05How far can 8 AWG wire run?
+−
At 40 A and 3 % drop, 57 ft one way at 120 V and 115 ft at 240 V (Table 8 resistance, 0.778 Ω per 1000 ft at 75 °C). Lighter loads go proportionally further.
06How many 8 AWG wires fit in ½" EMT?
+−
3 THHN conductors in ½" EMT, 6 in ¾" and 9 in 1" (NEC Chapter 9, 40 % fill for three or more).