16 NEC calculators - pipe fill, pipe sizing, voltage drop, wire size, box fill, EGC, GEC, motor FLA, transformer, generator, pipe bending, service entrance, load calc, ampacity derate, pull tension, Ohm's Law
Conduit bending - 11 bend types (offsets, rolling offsets, saddles, kicks, 90s, back-to-back) with tape-ready marks in 1/16ths, bender presets, full-stick layout, and a live Site Protractor
Quick Add wire tray - tap a gauge, drop a wire, NEC phase auto-rotates Black > Red > Blue, every tap haptic
Quick combos - 3-phase + N + G, 1-phase + N + G, MWBC, Feeder 100A drop entire circuit groups in one tap
NEC year-aware - switch between 2017 / 2020 / 2023 / 2026 in one tap, every calc recalibrates
Inspector-defendable - every result cites the NEC table or section it came from
Deep NEC compliance - Chapter 9 Note 5 nipple rule, Note 9 multiconductor cable, Note 4 bare grounds, TW/THW jacket split, 2020 EGC quarter-volume rule, full Polywater pull-tension formula
Field Mode - glove-friendly buttons, haptic confirmations, larger taps for the job site
Inspector-ready PDFs - exported reports stamped with your name, license #, and state
Projects with photos - save calcs to a job, mark up panel and splice photos, export the bundle
Live cross-section visualization - watch the conduit fill in real time with haptic threshold alerts
Built for offline - every NEC table is on-device, works in basements and crawlspaces
Guides
Conduit Fill Chart: How Many Wires Fit in EMT? - NEC caps conduit fill at 40% for 3 or more wires: 1/2 in EMT holds 9 THHN 12 AWG, 3/4 in holds 16, 1 in holds 26. Full chart, worked math, common mistakes.
How to Bend EMT Conduit: 90s, Offsets & Saddles - Subtract the take-up (5" for 1/2" EMT, 6" for 3/4"), mark, and bend to 90. Offsets: multiplier x depth between marks, plus shrink. Charts and worked examples.
Conduit Bending Multipliers & Offset Shrink Chart - Offset multipliers: 10° = 6.0, 22.5° = 2.6, 30° = 2.0, 45° = 1.4, 60° = 1.2. Marks = depth × multiplier; shrink runs 1/16" to 1/2" per inch of depth.
Box Fill Calculation Explained (NEC 314.16) - NEC 314.16 box fill: each conductor counts at its volume allowance (14 AWG = 2.0 cu in, 12 AWG = 2.25), each device counts as 2, all grounds as 1, clamps as 1.
Wire Size & Ampacity Chart (NEC 310.16) - NEC 310.16 copper chart: 12 AWG takes a 20 A breaker, 10 AWG 30 A, 8 AWG 50 A at 75°C, and 2 AWG covers 100 A. All three columns, derating, worked examples.
Conductor Derating in Conduit (NEC 310.15) - More than 3 current-carrying conductors in a conduit cuts ampacity: 4-6 wires keep 80%, 7-9 keep 70%, 10-20 keep 50%. Derate THHN from the 90C column.
Ground Wire Size Chart: EGC (250.122) & GEC (250.66) - NEC 250.122 copper EGC sizes: 15 A = 14 AWG, 20 A = 12, 30-60 A = 10, 70-100 A = 8, 110-200 A = 6. GECs follow 250.66 instead. Charts and worked examples.
At the NEC 40% fill limit, 3/4" EMT holds 16 #12 THHN or 10 #10 THHN conductors. But fill is only half the answer - with more than 3 current-carrying conductors you also owe ampacity derating, which usually caps a practical 3/4" pipe at nine current-carrying #12s. The app checks both in one screen.
Does the app calculate conduit bends, like QuickBend?
Yes - v1.5 added a full bending calculator with 11 bend types: offsets, rolling offsets, 3- and 4-point saddles, kicks, 90s, back-to-back and more. You get exact tape-ready marks in 1/16ths, a step-by-step "how to bend this" guide for every mark and flip, bender presets (Greenlee, Klein, IDEAL, Milwaukee, or your stamped deduct), a full-stick layout with cut mark, and a Site Protractor that reads the pipe angle when you lay the phone on it.
Which NEC year does Conduit Fill & Bending Calc support?
All four current cycles: NEC 2017, 2020, 2023, and 2026. Switch in one tap from the home screen and every calculation recalibrates to the tables published in that edition - so the math matches whichever code your AHJ enforces.
Are the calculations defendable to an inspector?
Every result cites the NEC table or section it came from - Chapter 9 Table 1 for fill, 310.16 for ampacity, 250.66 for GEC, 250.122 for EGC, 220.82 for dwelling load, 314.16(B) for box fill. The exported PDF reproduces every input plus the citation. Bring the PDF to the inspection.
What offset multiplier should I use for conduit bending?
The standard multipliers are 6.0 for 10°, 2.6 for 22.5°, 2.0 for 30°, 1.4 for 45°, and 1.2 for 60°. Multiply the offset depth by the multiplier to get the distance between bend marks. The app does this for you - including shrink - and rounds to tape-ready 1/16ths.
How deep does the NEC compliance go?
Deeper than most calculators on the App Store. Pipe Fill respects the Chapter 9 quirks most apps miss: the 53/31/40 fill rule, the 60% nipple rule for runs of 24 inches or less between enclosures, bare-conductor dimensions for grounds, and the multiconductor-cable-as-one-conductor rule. TW (60°C) and THW/THHW (75°C) are split into separate insulation types. Box Fill applies the 2020 NEC 314.16(B)(5) quarter-volume rule for additional EGC sets. Pull Tension uses the full Polywater straight-pull formula, so a vertical riser correctly reports double the tension of the same horizontal pull.
Do I have to derate THHN conductors in conduit?
When more than three current-carrying conductors share a raceway, NEC 310.15(C)(1) requires adjustment factors: 80% for 4-6 conductors, 70% for 7-9, 50% for 10-20. The Ampacity Derate calculator applies the factors, the ambient correction, and the termination cap in one pass - and cites each step.
Does it work without internet?
Yes. Every NEC table is on-device. Conduit Fill & Bending Calc runs in basements, crawlspaces, mechanical rooms, and remote job sites with no signal - and it's 11 MB, not a bloated reference suite.
What do I get with the full version?
All 16 NEC calculators, the complete bending suite with 11 bend types, every NEC year (2017 / 2020 / 2023 / 2026), unlimited project saves, inspector-ready PDF export with your license stamp, and photo attachments on calculations. Yearly is $9.99 with a 7-day free trial, Lifetime is $19.99 once, Monthly is $3.99.
How do I add my license to the PDF stamp?
Settings → License Information. Enter your name, license number, and state once; every PDF export from then on is stamped automatically.