Copper & Aluminum Wire Ampacity Chart
Base conditions: 30°C (86°F) ambient, not more than three current-carrying conductors, insulated conductors rated 0–2,000 V. These are base ampacities—not automatic breaker sizes.
No conductor matches those filters. Try 12 AWG, 1/0 AWG, or 500 kcmil.
Scroll horizontally to view all ampacity columns and vertically for additional wire sizes. Column headers and the wire-size column remain available while scrolling.
| Ampacity by conductor temperature rating | ||||
|---|---|---|---|---|
| 14 AWG | Copper | 15 A | 20 A | 25 A |
| 12 AWG | Copper | 20 A | 25 A | 30 A |
| 10 AWG | Copper | 30 A | 35 A | 40 A |
| 8 AWG | Copper | 40 A | 50 A | 55 A |
| 6 AWG | Copper | 55 A | 65 A | 75 A |
| 4 AWG | Copper | 70 A | 85 A | 95 A |
| 3 AWG | Copper | 85 A | 100 A | 115 A |
| 2 AWG | Copper | 95 A | 115 A | 130 A |
| 1 AWG | Copper | 110 A | 130 A | 145 A |
| 1/0 AWG | Copper | 125 A | 150 A | 170 A |
| 2/0 AWG | Copper | 145 A | 175 A | 195 A |
| 3/0 AWG | Copper | 165 A | 200 A | 225 A |
| 4/0 AWG | Copper | 195 A | 230 A | 260 A |
| 250 kcmil | Copper | 215 A | 255 A | 290 A |
| 300 kcmil | Copper | 240 A | 285 A | 320 A |
| 350 kcmil | Copper | 260 A | 310 A | 350 A |
| 400 kcmil | Copper | 280 A | 335 A | 380 A |
| 500 kcmil | Copper | 320 A | 380 A | 430 A |
| 600 kcmil | Copper | 350 A | 420 A | 475 A |
| 700 kcmil | Copper | 385 A | 460 A | 520 A |
| 750 kcmil | Copper | 400 A | 475 A | 535 A |
| 800 kcmil | Copper | 410 A | 490 A | 555 A |
| 900 kcmil | Copper | 435 A | 520 A | 585 A |
| 1000 kcmil | Copper | 455 A | 545 A | 615 A |
| 1250 kcmil | Copper | 495 A | 590 A | 665 A |
| 1500 kcmil | Copper | 525 A | 625 A | 705 A |
| 1750 kcmil | Copper | 545 A | 650 A | 735 A |
| 2000 kcmil | Copper | 555 A | 665 A | 750 A |
| 12 AWG | Aluminum / Cu-clad Al | 15 A | 20 A | 25 A |
| 10 AWG | Aluminum / Cu-clad Al | 25 A | 30 A | 35 A |
| 8 AWG | Aluminum / Cu-clad Al | 35 A | 40 A | 45 A |
| 6 AWG | Aluminum / Cu-clad Al | 40 A | 50 A | 55 A |
| 4 AWG | Aluminum / Cu-clad Al | 55 A | 65 A | 75 A |
| 3 AWG | Aluminum / Cu-clad Al | 65 A | 75 A | 85 A |
| 2 AWG | Aluminum / Cu-clad Al | 75 A | 90 A | 100 A |
| 1 AWG | Aluminum / Cu-clad Al | 85 A | 100 A | 115 A |
| 1/0 AWG | Aluminum / Cu-clad Al | 100 A | 120 A | 135 A |
| 2/0 AWG | Aluminum / Cu-clad Al | 115 A | 135 A | 150 A |
| 3/0 AWG | Aluminum / Cu-clad Al | 130 A | 155 A | 175 A |
| 4/0 AWG | Aluminum / Cu-clad Al | 150 A | 180 A | 205 A |
| 250 kcmil | Aluminum / Cu-clad Al | 170 A | 205 A | 230 A |
| 300 kcmil | Aluminum / Cu-clad Al | 195 A | 230 A | 260 A |
| 350 kcmil | Aluminum / Cu-clad Al | 210 A | 250 A | 280 A |
| 400 kcmil | Aluminum / Cu-clad Al | 225 A | 270 A | 305 A |
| 500 kcmil | Aluminum / Cu-clad Al | 260 A | 310 A | 350 A |
| 600 kcmil | Aluminum / Cu-clad Al | 285 A | 340 A | 385 A |
| 700 kcmil | Aluminum / Cu-clad Al | 315 A | 375 A | 425 A |
| 750 kcmil | Aluminum / Cu-clad Al | 320 A | 385 A | 435 A |
| 800 kcmil | Aluminum / Cu-clad Al | 330 A | 395 A | 445 A |
| 900 kcmil | Aluminum / Cu-clad Al | 355 A | 425 A | 480 A |
| 1000 kcmil | Aluminum / Cu-clad Al | 375 A | 445 A | 500 A |
| 1250 kcmil | Aluminum / Cu-clad Al | 405 A | 485 A | 545 A |
| 1500 kcmil | Aluminum / Cu-clad Al | 435 A | 520 A | 585 A |
| 1750 kcmil | Aluminum / Cu-clad Al | 455 A | 545 A | 615 A |
| 2000 kcmil | Aluminum / Cu-clad Al | 470 A | 560 A | 630 A |
Do not equate a table value with breaker size. Terminal ratings, conductor insulation, ambient temperature, current-carrying conductor count, small-conductor protection rules, equipment instructions, special applications, and the locally adopted code can impose a lower limit.
Code-edition note: NFPA publishes updated NEC editions on a three-year cycle, but jurisdictions adopt them on different schedules. Verify the edition and local amendments that govern the installation.
Table actions
How to Read the Wire Ampacity Chart
Find the wire size
Locate the AWG or kcmil designation and select copper or aluminum.
Use the allowed temperature column
60°C, 75°C, and 90°C values are not interchangeable; conductor and equipment ratings matter.
Apply required limits
Correct for ambient temperature and conductor count when required, then respect the lowest governing limitation.
AWG size progression
Lower AWG numbers mean larger conductors. After 1 AWG the sequence continues through 1/0, 2/0, 3/0, and 4/0 before kcmil sizes. The circles show proportional solid-equivalent conductor diameter; actual stranded cable outside diameter varies by construction.
Which Ampacity Temperature Column Should You Use?
The conductor’s insulation rating is only one part of the choice. Terminal and equipment temperature ratings can require a lower column, while a higher insulation rating may still be used where permitted as the starting point for correction and adjustment calculations.
Lower-temperature applications
Use when the applicable conductor, terminal, equipment, or code rule requires the 60°C ampacity column.
Common equipment column
Use when both the conductor application and connected equipment/terminations permit the 75°C column.
High-temperature insulation
Often relevant to conductors such as THHN/THWN-2 or XHHW-2. It is not automatically the final allowable circuit ampacity.
Key rule
Do not simply choose the highest number in the row. Verify conductor marking, wet/dry-location rating, terminal and equipment markings, conductor size, and applicable code rules.
Optional Wire Ampacity Derating Check
Use the base chart first. JavaScript enables this optional preliminary check for ambient-temperature and current-carrying-conductor adjustments.
Start from the conductor’s permitted insulation-temperature column, apply the two thermal factors below, then compare the result with the selected terminal/equipment temperature-column limit.
Ampacity Correction & Adjustment Factors
Adjusted ampacity = base ampacity × ambient-temperature factor × current-carrying-conductor factor. These thermal adjustments do not replace terminal limits, conductor-protection rules, equipment instructions, or special-application requirements.
Ambient-temperature correction factors
| Ambient | 60°C | 75°C | 90°C |
|---|---|---|---|
| ≤10°C | 1.29 | 1.20 | 1.15 |
| 11–15°C | 1.22 | 1.15 | 1.12 |
| 16–20°C | 1.15 | 1.11 | 1.08 |
| 21–25°C | 1.08 | 1.05 | 1.04 |
| 26–30°C | 1.00 | 1.00 | 1.00 |
| 31–35°C | 0.91 | 0.94 | 0.96 |
| 36–40°C | 0.82 | 0.88 | 0.91 |
| 41–45°C | 0.71 | 0.82 | 0.87 |
| 46–50°C | 0.58 | 0.75 | 0.82 |
| 51–55°C | 0.41 | 0.67 | 0.76 |
| 56–60°C | — | 0.58 | 0.71 |
| 61–65°C | — | 0.47 | 0.65 |
| 66–70°C | — | 0.33 | 0.58 |
| 71–75°C | — | — | 0.50 |
| 76–80°C | — | — | 0.41 |
| 81–85°C | — | — | 0.29 |
More than three current-carrying conductors
| Current-carrying conductors | Factor |
|---|---|
| 1–3 | 1.00 |
| 4–6 | 0.80 |
| 7–9 | 0.70 |
| 10–20 | 0.50 |
| 21–30 | 0.45 |
| 31–40 | 0.40 |
| 41 or more | 0.35 |
Do not assume every conductor in a raceway or cable is counted identically. Neutral-conductor treatment depends on circuit configuration and applicable rules; equipment grounding conductors are not normally current carrying.
Wire Ampacity Examples
12 AWG copper
The base row is 20 A at 60°C, 25 A at 75°C, and 30 A at 90°C. These are temperature-column ampacities, not three interchangeable breaker ratings. Small-conductor overcurrent-protection rules and equipment markings still need to be checked.
6 AWG copper in a hotter raceway
Using 90°C insulation at 36–40°C ambient with 4–6 current-carrying conductors gives 75 A × 0.91 × 0.80 = 54.6 A before other limits. A 75°C terminal cap is 65 A, so the 54.6 A thermal result is lower in this simplified check.
Ampacity, Breaker Size & Voltage Drop Are Different Checks
- Ampacity
- The conductor’s allowable current under defined thermal and installation conditions.
- Breaker or fuse size
- The protective-device rating selected under load, equipment, conductor-protection, and code rules.
- Voltage drop
- Voltage reduction caused by conductor impedance and circuit length; a long run can require a larger conductor even when ampacity is adequate.
- Design current
- The current the conductor and protective system must serve after applicable load rules are applied.
Common mistake
A wire can satisfy the ampacity table and still be too small for the application because of voltage drop, terminal limits, equipment instructions, or a special NEC rule.
Wire Ampacity Chart Sources & Scope
This page presents an educational, transformed reference based on NEC Table 310.16 ampacity values and related conductor-temperature, correction, and adjustment concepts. The official NFPA publication and the edition adopted by the authority having jurisdiction remain controlling for project work.
- NFPA 70, National Electrical Code — 2026 current editionPrimary code source for conductor ampacity, temperature limitations, correction and adjustment concepts.
- NFPA 2026 Table 310.16 development recordPublic NFPA material showing Table 310.16 values through 2000 kcmil and associated table notes.
- Cerrowire Ampacity ChartsManufacturer reference for common wire-size and insulation-temperature interpretation.
- Southwire CableTechSupportManufacturer engineering data and application notes, including reminders about conductor protection and temperature limitations.
- Edition basis
- NEC Table 310.16 reference; verify the edition and amendments adopted by the authority having jurisdiction
- Chart conditions
- 0–2,000 V; not more than three current-carrying conductors; 30°C ambient
- Covered sizes
- Copper 14 AWG–2000 kcmil; aluminum / copper-clad aluminum 12 AWG–2000 kcmil
- Calculated output
- Preliminary thermal adjustment and lower terminal-column comparison
- Not covered
- Project approval, all special applications, all alternate wiring methods, or local amendments
- Source checked
- October 4, 2026
Wire Ampacity Chart FAQs
How many amps can 12-gauge copper wire carry?
The base Table 310.16 values shown here are 20 A at 60°C, 25 A at 75°C, and 30 A at 90°C. The permitted circuit application can be lower because of terminal ratings, small-conductor protection rules, ambient temperature, conductor count, equipment requirements, and other code provisions.
What is the ampacity of 10 AWG copper wire?
The base values shown are 30 A at 60°C, 35 A at 75°C, and 40 A at 90°C. Separate small-conductor rules can govern even when a higher temperature-column ampacity appears in the table.
Why does one wire size have three amp ratings?
The 60°C, 75°C, and 90°C columns correspond to conductor temperature ratings. The allowed column depends on conductor insulation, terminal and equipment markings, conductor size, installation conditions, and applicable code requirements.
Can I always use the 90°C ampacity for THHN or THWN-2?
No. A permitted 90°C conductor rating may be used as the starting point for correction and adjustment calculations, but the final allowable ampacity can still be limited by lower-rated terminals, equipment, conductor-protection rules, and other requirements.
Does hot ambient temperature reduce ampacity?
It can. Table values use a 30°C reference ambient. When the applicable ambient is higher, the required correction factor can reduce allowable ampacity; multiple current-carrying conductors can require a separate adjustment as well.
Is ampacity the same as breaker size?
No. Ampacity is a conductor thermal limit under defined conditions. Breaker or fuse selection also depends on load characteristics, conductor protection, equipment instructions, permitted standard ratings, and special application rules.
Does wire length change ampacity?
Length does not directly change the base ampacity value in this chart, but longer circuits increase voltage drop. A larger conductor may therefore be needed even when the ampacity check passes.