For plumbers
PlumbCalc Pro
Plumbing Calculator Suite
Utilities · Free download · In-app purchases · Version 1.0 · 24 March 2026
Laborsam · Berlin
Apps and calculators for the building trades.
Every tool shows its working: the formula, a worked example, and the code edition and sections it cites.
- NEC calculators on the web
- 9
- Code edition
- NEC 2023
- Last calculator change
Worked example
- 01Each offset: the 22.5° multiplier times the rise4 × 2.6 = 10 3/8″ between the marks of one offset
- 02The two inner marks sit the length of the duct apart; the outer marks one offset further out on each side:2 × 10.4 + 12 = 32 13/16″ from the first mark to the last
- 03Shrink, for both offsets2 × 4 × 3/16 = 1 1/2″
Answer: Marks 10 3/8″, 12″, 10 3/8″ apart — 32 13/16″ overall, from the unrounded 10.4 in. — and 1 1/2″ of shrink.
From the conduit bending calculatorOpen this example in the calculator
Electrical
For electricians: Electric Master
Electric Master: NEC Panel
Wire Size, Box Fill & Schedule
Every code calculation names the section it used (Table 310.16, Chapter 9, 250.122, Article 220), so you can check it against your book and show your work to an inspector.
Free download · In-app purchases · iOS and iPadOS 17 or later
On the web: NEC calculators
Each one shows its formula, a worked example and the code sections it uses.
- Voltage Drop Calculator (NEC)Volts and percent dropped on a run, single- or three-phase, and the smallest size that stays within 3 %.
- Wire Size Calculator for AC Building Wiring (NEC)The conductor size for a load on AC building wiring, with terminal temperature, continuous loads, ambient and conductor count, and a voltage-drop check on this page.
- Wire Ampacity Chart: Copper and Aluminum (NEC Table 310.16)Table 310.16 ampacities at 60, 75 and 90 °C: copper from 14 AWG and aluminum from 12 AWG, up to 2000 kcmil.
- Ampacity Derating Calculator (NEC)Ampacity corrected for ambient temperature and adjusted for more than three current-carrying conductors in one raceway.
- Conduit Fill Calculator (NEC Chapter 9)The fill of mixed conductors in a raceway, how many more fit, and the smallest raceway that passes (Chapter 9).
- Box Fill Calculator (NEC 314.16)The volume a box needs for its conductors, yokes, clamps, grounds and fittings (314.16), and the standard boxes that hold it.
- Conduit Bending Calculator: Offsets, Saddles and ShrinkOffsets and 3- and 4-point saddles: mark spacing, shrink and the multipliers behind them.
- Ground Wire Size Calculator and Chart (NEC 250.122)The equipment grounding conductor for an overcurrent device (Table 250.122), with the upsizing rule and a chart.
- Grounding Electrode Conductor Size Calculator (NEC 250.66)The grounding electrode conductor for a service (Table 250.66), with parallel sets and the electrode limits.
Apps
More from Laborsam
For road trips in the US
RestStop Finder
Find Highway Rest Stops Nearby
Navigation · Free download · In-app purchases · Version 3.2.0 · 17 October 2026
The apps The catalog: each app with its price model, version and privacy policy.
Method
How the calculators are checked
- 01
Cited
Every code calculation names its section and the edition, NEC 2023, with the 2026 changes noted where they matter.
See a calculator - 02
One method, tested
The web calculators run the Electric Master app’s method, ported to the web and tested case by case against the app’s source code.
The calculators - 03
Dated changes
Each calculator keeps a dated changelog, and says so when the app’s current version gives a different number.
A calculator’s changelog - 04
A named author
Written and maintained by one named person with a mechanical-engineering degree, not a licensed electrician. Wrong numbers can be reported by email.
About the author
Who
Who is behind Laborsam
Laborsam is the name under which Yusuf Can Samiloglu publishes apps and web calculators: one person in Berlin, with a mechanical-engineering degree and a background in MEP/HVAC design and BIM. Not a licensed electrician: the electrical calculators follow the published code and cite it, and your AHJ has the final word.
Notes
Notes
- Building an HVAC SaaS Platform on My OwnHow I went from Excel-based HVAC calculations to building Mepbau — a cloud platform with 7 DIN-standard modules — as a solo founder with a day job.
- Building Revit Add-ins for MEP Engineers: Automating What Shouldn't Be ManualA practical guide to why and how MEP engineers should automate repetitive Revit tasks — from duct tagging to data export to batch parameter updates.
- From DIN Standards to API Endpoints: Encoding HVAC Calculations for the WebHow I translated DIN EN 12831 heating load calculations and VDI 2078 cooling load standards into a web-based calculation engine — the approach, the challenges, and the patterns.