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Printable AWG ampacity, resistance, and voltage-drop chart

Two tables for the bench or a PDF. Ampacity and resistance are the stored NEC cells. The voltage-drop columns are calculated from Table 8.

This sheet is a reference, not a second calculator. The ampacity half is the audited Table 310.16 cells, including the selected 14–10 AWG overcurrent ceilings this tool knows about. The resistance half is Table 8, stranded and solid where the row has a solid value. The volt columns beside the resistance are arithmetic at 1 A and 100 ft so a large conductor does not round to zero volts. They are useless as a shopping list: a 14 AWG row at 1 A is not permission to load 14 AWG to any current you later multiply.

Ambient correction, bundling, terminal temperature, continuous loads, and equipment listings are not baked into the cells. The ampacity chart page carries the factor tables. The calculator applies a specific circuit. Print the sheet, then do that other work. Local amendments can differ from the edition these cells were checked against.

Opens the browser print dialog on this device. Choose Save as PDF there. Printing does not upload the page to make the file.

Ampacity

Allowable ampacity in amperes from NEC Table 310.16. Not more than three current-carrying conductors, 30°C ambient. A dash means no listing for that metal and temperature, not zero. The last column is only the selected general 14–10 AWG overcurrent ceilings in this tool. A dash there is not permission to omit overcurrent protection. 18 and 16 AWG are shown for reference and are not offered as general power sizes. These cells are not corrected for other ambients or conductor counts.
Size Cu 60°C Cu 75°C Cu 90°C Al 60°C Al 75°C Al 90°C Selected 240.4(D)
18 AWG — — 14 — — — —
16 AWG — — 18 — — — —
14 AWG 15 20 25 — — — 15 Cu
12 AWG 20 25 30 15 20 25 20 Cu · 15 Al
10 AWG 30 35 40 25 30 35 30 Cu · 25 Al
8 AWG 40 50 55 35 40 45 —
6 AWG 55 65 75 40 50 55 —
4 AWG 70 85 95 55 65 75 —
3 AWG 85 100 115 65 75 85 —
2 AWG 95 115 130 75 90 100 —
1 AWG 110 130 145 85 100 115 —
1/0 AWG 125 150 170 100 120 135 —
2/0 AWG 145 175 195 115 135 150 —
3/0 AWG 165 200 225 130 155 175 —
4/0 AWG 195 230 260 150 180 205 —
250 kcmil 215 255 290 170 205 230 —
300 kcmil 240 285 320 195 230 260 —
350 kcmil 260 310 350 210 250 280 —
400 kcmil 280 335 380 225 270 305 —
500 kcmil 320 380 430 260 310 350 —
600 kcmil 350 420 475 285 340 385 —
700 kcmil 385 460 520 315 375 425 —
750 kcmil 400 475 535 320 385 435 —
800 kcmil 410 490 555 330 395 445 —
900 kcmil 435 520 585 355 425 480 —
1000 kcmil 455 545 615 375 445 500 —
1250 kcmil 495 590 665 405 485 545 —
1500 kcmil 525 625 705 435 520 585 —
1750 kcmil 545 650 735 455 545 615 —
2000 kcmil 555 665 750 470 560 630 —

Resistance and calculated voltage drop

Chapter 9 Table 8 resistance at 75°C, ohms per 1,000 feet. Stranded columns are uncoated. Solid columns appear only where this chart’s Table 8 row lists them. Voltage-drop columns are calculated, not a separate NEC table: 1 A and 100 one-way feet, Table 8 stranded resistance, reactance omitted. Single-phase or DC uses 2 × I × R × L / 1,000. Balanced three-phase uses √3 and line-to-line voltage. Display keeps extra decimals so large conductors do not round to zero. Multiply by actual amperes and by one-way length in hundreds of feet. A resistance without an ampacity listing is not permission to use that conductor. These columns are not an allowable-load table.
Size Cu stranded Ω/kft Al stranded Ω/kft Cu solid Ω/kft Al solid Ω/kft Cu 1φ/DC V Al 1φ/DC V Cu 3φ V Al 3φ V
18 AWG 7.95 13.1 7.77 12.8 1.59 2.62 1.38 2.27
16 AWG 4.99 8.21 4.89 8.05 0.998 1.64 0.864 1.42
14 AWG 3.14 5.17 3.07 5.06 0.628 1.03 0.544 0.895
12 AWG 1.98 3.25 1.93 3.18 0.396 0.650 0.343 0.563
10 AWG 1.24 2.04 1.21 2 0.248 0.408 0.215 0.353
8 AWG 0.778 1.28 0.764 1.26 0.156 0.256 0.135 0.222
6 AWG 0.491 0.808 — — 0.0982 0.162 0.0850 0.140
4 AWG 0.308 0.508 — — 0.0616 0.102 0.0533 0.0880
3 AWG 0.245 0.403 — — 0.0490 0.0806 0.0424 0.0698
2 AWG 0.194 0.319 — — 0.0388 0.0638 0.0336 0.0553
1 AWG 0.154 0.253 — — 0.0308 0.0506 0.0267 0.0438
1/0 AWG 0.122 0.201 — — 0.0244 0.0402 0.0211 0.0348
2/0 AWG 0.0967 0.159 — — 0.0193 0.0318 0.0167 0.0275
3/0 AWG 0.0766 0.126 — — 0.0153 0.0252 0.0133 0.0218
4/0 AWG 0.0608 0.1 — — 0.0122 0.0200 0.0105 0.0173
250 kcmil 0.0515 0.0847 — — 0.0103 0.0169 0.0089 0.0147
300 kcmil 0.0429 0.0707 — — 0.0086 0.0141 0.0074 0.0122
350 kcmil 0.0367 0.0605 — — 0.0073 0.0121 0.0064 0.0105
400 kcmil 0.0321 0.0529 — — 0.0064 0.0106 0.0056 0.0092
500 kcmil 0.0258 0.0424 — — 0.0052 0.0085 0.0045 0.0073
600 kcmil 0.0214 0.0353 — — 0.0043 0.0071 0.0037 0.0061
700 kcmil 0.0184 0.0303 — — 0.0037 0.0061 0.0032 0.0052
750 kcmil 0.0171 0.0282 — — 0.0034 0.0056 0.0030 0.0049
800 kcmil 0.0161 0.0265 — — 0.0032 0.0053 0.0028 0.0046
900 kcmil 0.0143 0.0235 — — 0.0029 0.0047 0.0025 0.0041
1000 kcmil 0.0129 0.0212 — — 0.0026 0.0042 0.0022 0.0037
1250 kcmil 0.0103 0.0169 — — 0.0021 0.0034 0.0018 0.0029
1500 kcmil 0.00858 0.0141 — — 0.0017 0.0028 0.0015 0.0024
1750 kcmil 0.00735 0.0121 — — 0.0015 0.0024 0.0013 0.0021
2000 kcmil 0.00643 0.0106 — — 0.0013 0.0021 0.0011 0.0018

Planning estimate only. Consult local code and a qualified electrician before buying wire or energizing a circuit. Presets are hypothetical loads; this tool does not design motor, PV, battery, appliance, or EV installations.

Sources for these cells: existing Table 310.16 numerical cells in NFPA’s public development record, pp. 142–143 (proposed changes are not treated as adopted code) and NFPA 70 (2017), Chapter 9 Table 8, printed p. 689, in a third-party-hosted copy. The same publication supplies 110.14 (terminals and aluminum), 210.19/215.2 (continuous loads), 240.4(D) (small conductors), 250.24/250.32 (grounding), and 625.41/625.42 (EV loads). Schneider Electric’s voltage-drop formulas support the arithmetic; Table 8 AC results here omit reactance and assume unity power factor. Resistance and geometry are construction- and temperature-specific. Adopted editions and local amendments can differ.

Related guides

Open the wire size calculator · Ampacity chart · Voltage drop calculator · Printable chart

Questions

Are the voltage-drop columns an NEC table?

No. Ampacity is NEC Table 310.16. Resistance is Chapter 9 Table 8 at 75°C. The volt columns are calculated for 1 A and 100 one-way feet from the stranded resistance, using 2 × I × R × L / 1,000 for single-phase or DC and √3 for balanced three-phase. Reactance is omitted. Multiply by the real current and by the one-way length in hundreds of feet. They are not an allowable-load table.

Do these ampacity numbers include attic temperature or a full conduit?

No. The ampacity columns are the base table: 30°C ambient and not more than three current-carrying conductors. Other conditions use the correction and adjustment tables on the ampacity chart. A dash is a missing listing, not zero, and a dash in the small-conductor column is not permission to omit overcurrent protection.

How do I save this chart as a PDF?

Use Print / Save as PDF. The button opens the browser’s print dialog on this device and does not upload the page to a server. Choose Save as PDF, or a printer, in that dialog. Landscape letter paper fits the columns more comfortably. The on-screen navigation is omitted from the printout. Planning estimate only. Consult local code and a qualified electrician.