What is the amp rating for 10 gauge wire?

Use 32 A for 10 AWG copper on equipment with 75 °C terminations, which covers most breakers and panel lugs. Read 27 A instead when the conductor is inside NM-B cable, and treat 37 A as the derating base only. Aluminium of the same size is about 25 A at 75 °C.

What breaker size goes with 10 AWG copper?

The largest standard overcurrent device that 10 AWG copper supports at 75 °C is 30 A. For a continuous load, the load itself must not exceed 80% of that rating.

What is the diameter of 10 AWG wire?

The bare conductor is 0.1019 inches (2.588 mm) in diameter, which is 10,383 circular mils. With THHN/THWN-2 insulation the nominal outside diameter is about 0.164 inches.

What is the resistance of 10 AWG wire?

About 0.9988 ohms per 1000 feet for copper and 1.6373 ohms per 1000 feet for aluminium, at 75 °C.

How far can I run 10 AWG wire?

Distance depends on load and voltage. At 20 A on a 120 V single-phase circuit, 10 AWG copper stays under 3% voltage drop for about 72 feet one-way. Doubling the voltage roughly doubles the allowable distance.

10 AWG Wire — Amp Rating, Ampacity & Diameter

Ampacity, geometry, resistance, conduit fill and maximum run length for 10 AWG conductors in copper and aluminium.

Quick answer

10 AWG copper carries about 32 A at 75 °C (27 A at 60 °C, 37 A at 90 °C). The bare conductor is 0.1019 in (2.59 mm) and 10,383 circular mils, with 0.9988 Ω per 1000 ft. It pairs with a 30 A breaker at 75 °C terminations.

Copper 75 °C

32A

Aluminium 75 °C

25A

Diameter

0.1019in

Circular mils

10,383

Full specification

Size designation	10 AWG
AWG gauge number	10
Circular mils	10,383
kcmil	10.38
Bare diameter (in)	0.1019
Bare diameter (mm)	2.588
Cross-section (mm²)	5.26
THHN/THWN-2 OD (in)	0.164
Insulated area (sq in)	0.0211
Copper resistance (Ω/1000 ft)	0.9988
Aluminium resistance (Ω/1000 ft)	1.6373
Max standard breaker (Cu, 75 °C)	30 A

Published standardFormula estimate

Ampacity with derating

Estimated ampacity from the 90 °C column at various ambient temperatures and conductor counts.

Conductors in raceway	30 °C ambient	40 °C ambient	50 °C ambient	60 °C ambient
3	37 A	34 A	30 A	26 A
6	30 A	27 A	24 A	21 A
9	26 A	24 A	21 A	18 A
15	19 A	17 A	15 A	13 A
25	17 A	15 A	14 A	12 A

Source & method: The governing value is also capped by the termination rating, commonly 75 °C, which for this size is 32 A. Run your own conditions.

Maximum run length at 3% voltage drop

One-way distance for 10 AWG copper before drop exceeds 3%.

Load	120 V 1Ø	240 V 1Ø	208 V 3Ø	480 V 3Ø
10 A	144 ft	289 ft	289 ft	669 ft
15 A	96 ft	193 ft	193 ft	446 ft
20 A	72 ft	144 ft	144 ft	334 ft
30 A	48 ft	96 ft	96 ft	223 ft
40 A	36 ft	72 ft	72 ft	167 ft
50 A	28 ft	57 ft	57 ft	133 ft

Calculate your exact run

How many 10 AWG conductors fit in conduit

Maximum count of this size alone, at the fill percentage matching the resulting count.

Conduit	1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"	3"	3-1/2"	4"
EMT	5	10	16	28	38	63	110	167	218	279
IMC	6	11	18	31	42	68	97	150	200	258
RMC	5	10	16	28	39	64	92	142	189	243
PVC Sch 40	5	9	15	27	37	62	88	137	184	237
PVC Sch 80	4	7	13	23	32	54	77	121	164	213

Mix conductor sizes in the fill calculator

10 AWG copper ampacity vs aluminium ampacity

Ampacity by conductor material and insulation temperature rating, at 30 °C ambient with no more than three current-carrying conductors.

Material	60 °C (TW, NM-B)	75 °C (THW, THWN, XHHW)	90 °C (THHN, THWN-2, XHHW-2)
Copper	27 A	32 A	37 A
Aluminium	21 A	25 A	28 A

The 10 AWG copper ampacity figure you use on a real circuit is the 75 °C column, 32 A, because breakers and lugs on most equipment are listed for 75 °C even when the conductor insulation is rated 90 °C. The 90 °C value, 37 A, is the starting point for ambient and conductor-count derating only — you derate from 90 °C, then cap the answer at the termination rating.

Aluminium of the same size carries roughly 78% of the copper value (25 A at 75 °C), so an aluminium feeder is normally stepped up one to two sizes to match a copper circuit. NM-B cable is always read from the 60 °C column regardless of the temperature stamped on the conductor insulation.

Source & method: Values are model estimates from conductor geometry and resistivity — see methodology and verify against the NEC edition enforced locally.

Neighbouring sizes

Compare 10 AWG with the sizes immediately above and below it before sizing a circuit.

Smaller12 AWG24 A copper at 75 °C · 0.0808" diameter Larger8 AWG44 A copper at 75 °C · 0.1285" diameter

Size	Cu 75 °C	Al 75 °C	Diameter (in)	Circular mils
14 AWG	18 A	14 A	0.0641	4,107
12 AWG	24 A	19 A	0.0808	6,530
10 AWG (this page)	32 A	25 A	0.1019	10,383
8 AWG	44 A	34 A	0.1285	16,510
6 AWG	59 A	46 A	0.1620	26,251

Circuits that use 10 AWG

Breaker ratings whose smallest copper conductor at 75 °C terminations is 10 AWG.

10 AWG amp rating, diameter and metric equivalent

The amp rating for 10 AWG wire depends on the insulation temperature rating, not on the conductor alone. Copper ampacity is about 27 A on a 60 °C conductor, 32 A at 75 °C and 37 A at 90 °C, all at 30 °C ambient with no more than three current-carrying conductors in the raceway. The carrying capacity drops from there in hot spaces or crowded conduit, and terminations rated 75 °C cap what you can actually use.

Geometrically, 10 AWG is 0.1019 in (2.59 mm) in bare diameter, which is 10,383 circular mils. The cross sectional area works out to 5.26 mm², so the nearest IEC 60228 metric conductor is the next standard size at or above that figure — AWG sizes and mm² sizes never line up exactly, so round up rather than to the closest value.

American Wire Gauge (AWG) is a standard specification for the sizes of solid round wires used as electrical conductors, and the AWG number counts the drawing operations used to reach the diameter. That is why larger gauges are thinner wire and why standardized wire steps follow a fixed ratio: one AWG step changes diameter by about 12.2% and area by about 26%. Above 1 AWG the American standard continues 1/0 to 4/0, then switches to kcmil for anything larger.

Where 10 AWG actually gets used

10 AWG is the first size past general-purpose wiring: 30 A in ordinary building wiring under the small-conductor rule, used for electric water heaters, window and through-wall air conditioners, small subpanel feeders, well pumps, and dryer circuits on older 30 A installations. It is also the common choice for long 20 A runs where voltage drop, not ampacity, forces the upsize.

Because it is stranded far more often than 14 or 12, terminations change character here. Screw terminals on 30 A devices, ring lugs, and split-bolt connections all appear, and torque specification starts to matter more than conductor selection. Solid 10 AWG in NM-B is stiff enough that box fill and bend radius become the practical constraint in a device box rather than the wire's rating.

Frequently asked

How many amps can 10 AWG wire carry?: 10 AWG copper is estimated at 27 A at 60 °C, 32 A at 75 °C and 37 A at 90 °C, at 30 °C ambient with no more than three current-carrying conductors. Aluminium of the same size is about 25 A at 75 °C.
What is the amp rating for 10 gauge wire?: Use 32 A for 10 AWG copper on equipment with 75 °C terminations, which covers most breakers and panel lugs. Read 27 A instead when the conductor is inside NM-B cable, and treat 37 A as the derating base only. Aluminium of the same size is about 25 A at 75 °C.
What breaker size goes with 10 AWG copper?: The largest standard overcurrent device that 10 AWG copper supports at 75 °C is 30 A. For a continuous load, the load itself must not exceed 80% of that rating.
What is the diameter of 10 AWG wire?: The bare conductor is 0.1019 inches (2.588 mm) in diameter, which is 10,383 circular mils. With THHN/THWN-2 insulation the nominal outside diameter is about 0.164 inches.
What is the resistance of 10 AWG wire?: About 0.9988 ohms per 1000 feet for copper and 1.6373 ohms per 1000 feet for aluminium, at 75 °C.
How far can I run 10 AWG wire?: Distance depends on load and voltage. At 20 A on a 120 V single-phase circuit, 10 AWG copper stays under 3% voltage drop for about 72 feet one-way. Doubling the voltage roughly doubles the allowable distance.