The stripper card
Notches from 4/0 to 24 AWG at true width for stranded copper; slide a stripped wire into the first notch it fits. The NEC Table 310.16 chart and the ½"–2" EMT fill chart print on the same sheet for the shop wall.
Printable 1:1 wire stripper gauge & shop charts
Printable wire gauge: a true-size stripper notch card from 4/0 to 24 AWG, the NEC Table 310.16 chart and an EMT fill chart on one page. Print at 100 %, check the 50 mm bar, then test a wire in the notches. No printer? The on-screen comb above draws the same notches at 1:1.
01 · 1:1 wire gauge · stripper comb
12 AWG · concentric stranded copper
THIS IS:
12 AWG COPPER · 20 A BREAKER · 2.05 MM COPPER
Gauge
12 AWG
concentric stranded copper
Breaker
20 A
copper, max
Measured
2.34 mm
0.0920"
The gap is 2.34 mm (0.0920"), which reads as 12 AWG concentric stranded 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
12 AWG
- Solid diameter
- 0.0808"2.053 mm · ASTM B258 formula
- Stranded (7 strands)
- 0.0920"2.337 mm · Table 8
- THHN outside
- 0.130"3.30 mm · 0.0133 in² · Table 5
- Area
- 6,530 cmil3.31 mm² · nearest IEC 4 mm²
- DC resistance, 75 °C
- 1.98 Ω/1000 ftaluminum 3.25 Ω/1000 ft · Table 8
- Copper weight
- 19.8 lb/1000 ft
Ampacity
- Copper 60 / 75 / 90 °C
- 20 / 25 / 30 ANM-B uses the 60 °C column (334.80)
- Aluminum 60 / 75 / 90 °C
- 15 / 20 / 25 A
- Largest breaker (Cu, 75 °C)
- 20 A240.4(D) small-conductor cap
Other gauges
- Nearest SWG
- SWG 130.092" · 2.337 mm
- IEC 60228
- 4 mm²between 2.5 and 4 mm²
Printable 1:1 stripper gauge card
Print at 100 % (actual size), then measure the control bar: it must be exactly 50 mm. Slide a stripped wire into the first notch it fits; widths are Table 8 stranded diameters, so solid wire drops one notch further.
Printable shop charts 46 rows
Sort any column, print a shop sheet, download CSV. Click a row to load it in the calculator.
Solid diameters from the AWG formula (ASTM B258); stranding, stranded diameters and resistance from NEC Chapter 9 Table 8; ampacity from Table 310.16 (NEC 2023), 30 °C ambient, not more than three current-carrying conductors.
Values agree across Elliott Electric (2020 NEC), Cerrowire (2017 NEC) and Southwire SPEC 10028 (2023 NEC). NEC 2026 adds 16 AWG copper and 14 AWG copper-clad aluminum rows.
Counts reproduce NEC Annex C (Table C.1 for EMT) from the Chapter 9 tables; mixed sizes use the calculator above.
05 / Field guide
Paper that
stays true.
A printed gauge is only as good as the print scale. Print at 100 % (not “fit to page”) and measure the 50 mm control bar before trusting a notch; most printers hold scale within half a percent when set correctly.
On screen instead
The on-screen comb draws the same notches at 1:1 after you calibrate with a coin or a card, and the fullscreen mat adds conduit outside diameters.
Why the screen can be trusted
A browser does not know how big its pixels are, so the gauge starts from a table of 114 phones, tablets, laptops and monitors matched to your screen’s size and pixel ratio, an estimate good to about five percent. Laying a coin or a bank card on the glass and matching its outline replaces the estimate with a measurement good to a fraction of a percent, saved for this screen only.
Browser zoom is corrected automatically from the pixel ratio; pinch zoom is flagged, because nothing drawn is true size until it is undone.
pixels per mm = CSS px across the card ÷ 85.60 mm ID-1 card: 85.60 × 53.98 mm (ISO/IEC 7810)
Getting a true-size print
Print from a desktop browser or the PDF, at 100 % or “actual size”, with headers and footers off. Phones and some print dialogs shrink the page to fit the margins; that is the most common cause of a card that measures 48 mm instead of 50 mm. If the control bar is off, the error is the same percentage everywhere on the sheet, so fix the scale and reprint rather than correcting by eye.
Card stock or a laminated sheet lasts longer in a tool bag; cut the notches with a sharp blade along the printed lines.
Using the notch card safely
Only test de-energised wire. Strip a short length and slide the bare copper into the notches from the largest down; the first notch it will not enter is one size too small. Stranded wire that has been crushed or twisted reads one size larger, so test an end you have just cut.
Questions
Answered plainly.
01How do I print at true size?
+−
Choose 100 % or “actual size” in the print dialog, turn off “fit to page”, then measure the 50 mm bar with a ruler.
02Can I laminate the chart?
+−
Yes; lamination adds a few tenths of a millimetre of plastic, so read wire fits by the notch edges, not the laminate.
03Why stranded widths?
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Most building wire 8 AWG and up is stranded; Table 8 stranded diameters are slightly larger than solid ones, so a solid wire will drop one notch further.
04Is the printed ampacity chart the full table?
+−
Copper, 14 AWG to 500 kcmil, at 60, 75 and 90 °C, with the largest breaker each may take; aluminum and derating are on the ampacity page.
05Letter or A4?
+−
Either: nothing on the sheet depends on the paper size, only on printing at 100 %.
06My printed control bar is 48 mm. What went wrong?
+−
The page was scaled down, usually by “fit to page” or a phone’s print dialog. Print at 100 % from a desktop browser and check the bar again.
07Can I use the card on insulated wire?
+−
No, it is cut for bare copper. Use the insulated profile of the on-screen gauge to compare a jacket’s outside diameter.