ElecCalcs
Reference chart

Wire Size Chart

AWG and kcmil conductor sizes with circular-mil area and allowable ampacity. The ampacity columns are base values — apply the ambient and raceway corrections with the ampacity calculator, or let the wire size calculator pick the smallest size that meets the load.

Quick reference: circuit rating to conductor size

Smallest size for a noncontinuous load, assuming 60°C terminations at or below 100 A and 75°C above 100 A, 30°C ambient and three current-carrying conductors. Confirm actual equipment and terminal ratings. Each rating links to its own page with the full correction chain.

Circuit ratingCopperAluminumDetails
15 A14 AWG12 AWG15 amp wire size
20 A12 AWG10 AWG20 amp wire size
25 A10 AWG10 AWG25 amp wire size
30 A10 AWG8 AWG30 amp wire size
35 A8 AWG8 AWG35 amp wire size
40 A8 AWG6 AWG40 amp wire size
45 A6 AWG4 AWG45 amp wire size
50 A6 AWG4 AWG50 amp wire size
60 A4 AWG3 AWG60 amp wire size
70 A4 AWG2 AWG70 amp wire size
80 A3 AWG1 AWG80 amp wire size
90 A2 AWG1/0 AWG90 amp wire size
100 A1 AWG1/0 AWG100 amp wire size
125 A1 AWG2/0 AWG125 amp wire size
150 A1/0 AWG3/0 AWG150 amp wire size
200 A3/0 AWG250 kcmil200 amp wire size
250 A250 kcmil350 kcmil250 amp wire size
300 A350 kcmil500 kcmil300 amp wire size
400 A600 kcmil1000 kcmil400 amp wire size

AWG wire size chart

Circular-mil values are nominal table values and may be rounded; THHN/THWN-2 cross-section is the value used for conduit fill. Ampacity values are the base table before any correction factor is applied — see the full wire ampacity chart for the aluminum 60°C and 90°C columns.

The mm² column is geometry only. A size conversion is not a rating conversion, which is what the mm² to AWG chart explains.

Sizemm²Circular milsTHHN area (sq in)Cu 60°CCu 75°CCu 90°CAl 75°C
142.084,1100.009715 A20 A25 A—
123.316,5300.013320 A25 A30 A20 A
105.2610,3800.021130 A35 A40 A30 A
88.3716,5100.036640 A50 A55 A40 A
613.326,2400.050755 A65 A75 A50 A
421.1541,7400.082470 A85 A95 A65 A
326.6652,6200.097385 A100 A115 A75 A
233.6366,3600.115895 A115 A130 A90 A
142.4183,6900.1562110 A130 A145 A100 A
1/053.51105,6000.1855125 A150 A170 A120 A
2/067.44133,1000.2223145 A175 A195 A135 A
3/085.03167,8000.2679165 A200 A225 A155 A
4/0107.22211,6000.3237195 A230 A260 A180 A
250126.68250,0000.397215 A255 A290 A205 A
300152.01300,0000.4608240 A285 A320 A230 A
350177.35350,0000.5242260 A310 A350 A250 A
400202.68400,0000.5863280 A335 A380 A270 A
500253.35500,0000.7073320 A380 A430 A310 A
600304.02600,0000.8676350 A420 A475 A340 A
750380.03750,0001.0496400 A475 A535 A385 A
1000506.711,000,0001.3478455 A545 A615 A445 A

How to read this chart

  • Find the load first. Conductor size follows the overcurrent device and the load, not the other way round — a 20 A breaker with 14 AWG copper on it is a code violation even though the wire will physically carry the current for a while.
  • Base ampacity is a starting point. Ambient temperature above 30°C and more than three current-carrying conductors in one raceway both reduce what the conductor may carry.
  • Terminations can cap you below the insulation rating. A 90°C conductor on 60°C terminations is limited to the 60°C column.
  • Voltage drop is a separate check. On long runs the voltage drop calculator often forces a larger size than ampacity alone would require.

Frequently asked

What does AWG mean on a wire size chart?
AWG stands for American Wire Gauge. It is an inverse scale: a smaller number is a larger conductor. 14 AWG carries less current than 8 AWG, and above 4/0 the chart switches to kcmil (thousands of circular mils), where the number is the area itself — 250 kcmil is 250,000 circular mils.
What is the difference between AWG and kcmil?
Both describe the same thing — conductor area — in different units. AWG is a gauge number for sizes up to 4/0; kcmil (also written MCM) is thousands of circular mils and is used for larger sizes. One circular mil is the area of a circle one thousandth of an inch across.
Why does the chart show three ampacity columns?
Because a conductor's allowable current depends on the temperature rating of its insulation. The same copper conductor appears in the 60°C, 75°C and 90°C columns with different values; you use the column that matches the insulation and the temperature rating of the terminations, not simply the highest number.
Which column should I use for a typical branch circuit?
For equipment rated 100 A or less, the 60°C column is the conservative starting assumption unless the applicable rules and equipment markings permit a higher rating. Verify both terminations, conductor insulation and installation conditions; apply adjustments as required.
Does this chart apply to aluminum conductors?
The aluminum column is shown for 75°C. Aluminum is generally one to two sizes larger than copper for the same current, and small aluminum sizes below 12 AWG are not covered. Confirm that the terminations you are using are listed for aluminum before mixing materials.

Table values reflect NEC 2023 and are pending review. Educational information only — not professional engineering advice. Verify before ordering cable.