Electrical, plumbing, HVAC, welding, masonry, carpentry, estimating & conversions — all code-compliant, all offline, all in your pocket.
33 calculators free forever · $19.99 per trade · $49.99 for everything
Grouped by workflow, not alphabetically. Wire & conduit first, then service & load, then motors. The way your day goes.
Every calculation references the actual code book tables — not approximations. The same tables your inspector uses.
Table 9 impedance values with AC skin effect correction for 2/0+ conductors. Table 310.16 ampacity. Chapter 9 conduit fill percentages.
DFU tables, fixture unit calculations, gas pipe sizing per IFGC. Drainage slope and water supply demand curves.
R311.7.2 headroom clearance for stairs. Joist span tables. Rafter sizing. Floor opening calculations for code-compliant stairways.
NEC Table 9 impedance values — not the simplified DC resistance most apps use. Includes AC skin effect correction for conductors 2/0 AWG and larger, power factor input, and automatic pass/fail against NEC 210.19(A) and 215.2(A) thresholds.
Input total rise, and the calculator outputs riser height, tread depth, number of treads, total run, stringer length, and the floor opening dimension for IRC R311.7.2 headroom clearance. No more guessing if your header is far enough back.
Pair a Bosch GLM 165-27CGL laser measurer — shoot a distance and it drops into the active field. Total rise for stairs. Conduit run for voltage drop. Room length for drywall sheets. No keypad. No walking back because you fat-fingered 147 instead of 174.
Connect an Owon OW18E multimeter and live readings — voltage, current, resistance — stream straight into your electrical calculators. Verify a circuit, and the numbers are already where they need to be. Quicker inputs. Shorter workdays.
10 welding calculators including AWS D1.1 preheat requirements, carbon equivalent (CE & Pcm), heat input, filler metal selection, and gas flow rates. Builder's Helper doesn't have it. Construction Master doesn't either. Nobody does.
Every calculation generates a clean, branded PDF with your inputs, the step-by-step work, and the code reference. Share it with your foreman, email it to the inspector, or save it to your project folder. Professional documentation from the field.
Every calculator feeds the same system. Calculate, tap "Add to Project," pick the job — done. Every number you've ever run, organized by trade, under one job name. Come back in a week or a year. It's all there.
No "active project" to set. Run any calc, tap the button, pick the job from a list sorted by last used. Three taps.
Wire sizing files under Electrical. Concrete volume files under Masonry. You never tag, label, or sort anything.
Open a project from three months ago. Every wire size, every rafter length, every P/T reading — right where you left it.
Export any calculation as a branded PDF with inputs, work, and code references. Send it to your foreman, inspector, or GC.
33 calculators free. The rest for $19.99 a trade. Your jobs, your calcs, your system.
Download on the App StoreMasonry, welding, estimating, and conversions — free forever. No trial, no credit card, no bait-and-switch. When you're ready for more, pay once and own it.
A side-by-side breakdown against the two most popular construction calculator apps on the App Store.
| Feature | Contractor's Cheatsheet | Construction Master Pro | Builder's Helper MAX |
|---|---|---|---|
| Total calculators | 97 | ~12 | 16 |
| Trades covered | 8 dedicated trades | Dimensional math only | Carpentry / GC only |
| Electrical | |||
| Wire sizing (NEC 310.16) | Included | -- | -- |
| Conduit fill (Chapter 9) | Included | -- | -- |
| Voltage drop (Table 9 impedance) | Included | -- | -- |
| Box fill / Service load / Motor FLC | Included | -- | -- |
| Plumbing | |||
| Pipe sizing (IPC) | Included | -- | -- |
| DFU count / Fixture units | Included | -- | -- |
| Gas line sizing / Drainage slope | Included | -- | -- |
| Welding | |||
| Preheat (AWS D1.1) | Included | -- | -- |
| Carbon equiv. / Heat input / Filler metal | Included | -- | -- |
| HVAC | |||
| Duct sizing (Huebscher) | Included | -- | -- |
| Refrigerant P/T chart (18 refrigerants) | Included | -- | -- |
| Superheat / Subcooling / Airflow ΔT | Included | -- | -- |
| Carpentry | |||
| Stair layout | + floor opening (IRC) | Basic | Basic |
| Rafter / Roof pitch | Included | Basic | Included |
| Concrete / Block / Footing | + turn-down footings | -- | Basic volume |
| Drywall / Flooring / Decking | Included | -- | Included |
| Crown miter / Board feet | Included | -- | Included |
| Joist span tables | Included | -- | -- |
| Masonry | |||
| Block count / Rebar / Mortar / Grout | Included | -- | Block only |
| General | |||
| Code compliance tables | NEC · IPC · IRC | None | None |
| PDF reports with code refs | Branded PDF | -- | PDF export |
| Feet-inch-fraction math | Included | Primary feature | Included |
| Metric / Unit conversions | 8 converters | Basic | Basic |
| Works offline | 100% | Yes | Yes |
| Bluetooth tools | Bosch laser · Owon multimeter | -- | -- |
| Pricing | $0–49.99 once | $20-36/yr subscription | ~$6 one-time |
| Cost after 3 years | $0–49.99 | $60-108 | ~$6 |
Yes. Every calculator works without an internet connection. All code tables are built into the app. Use it in a basement, on a roof, in a tunnel — anywhere you have your phone.
The app defaults to NEC 2023 and includes a toggle for 2020 where table values differ. Impedance values, ampacity tables, and conduit fill percentages are pulled directly from the code book.
Yes. Every calculation generates a branded PDF showing your inputs, step-by-step work, and code references. Share via AirDrop, text, email, or save to your files.
Masonry (10 calcs), Welding (10 calcs), Estimating (5 calcs), and Conversions (8 calcs) are free forever — no trial, no catch. The four pro trades — Electrical, Plumbing, HVAC, and Carpentry — are $19.99 each, or $49.99 for all. Buy them one at a time; you'll never pay more than $49.99 total. If your purchases add up to $49.99, every remaining trade unlocks automatically.
iOS first, Android on the roadmap. If you want to be notified when it ships, drop your email below.
Construction Master is a feet-inch-fraction calculator with basic dimensional math. It has zero trade-specific calculators, no code compliance, no NEC tables, no pipe sizing, no welding — and charges $20–36/year. This app has 89 calculators across 8 trades for one payment.
Report bugs, request features, share tips. Every post gets a real response from the person building this thing.
The only app that uses NEC Table 9 impedance values instead of simplified DC resistance.
15 calculators built around the NEC — wire sizing, conduit fill, voltage drop, service load, motor circuits. Every table your inspector references is already inside. Pair a Bosch GLM 165-27CGL laser and distances land in your calculator — conduit runs, raceway lengths, no keypad. Connect an Owon OW18E multimeter and live voltage, current, and resistance flow straight into your electrical calcs. No clipboard. No re-reading. Every calculation saves to your project.
Full access to all 15 electrical calculators.
Download for iOSOffset travel, pipe specs, fixture units, gas sizing — every plumber's daily math in one place.
13 calculators covering pipe layout, water supply, drainage, and gas. IPC/UPC tables built in. No more flipping through the Blue Book on the truck. Every calculation saves to your project.
Full access to all 13 plumbing calculators.
Download for iOSP/T charts for 18 refrigerants, superheat/subcooling, airflow Delta-T, temperature rise — every service call calc in one place.
10 calculators covering load sizing, duct design, refrigerant diagnostics, airflow analysis, and ventilation. Replaces 3–4 separate HVAC apps. Every calculation saves to your project.
The tab no other construction app has. Period.
10 welding calculators including AWS D1.1 preheat, carbon equivalent, heat input, filler metal selection, and cost estimation. Every calculation saves to your project.
No account required. No credit card. Just download and go.
Download for iOS26 calculators — more than any other construction app's entire library.
Framing, roofing, stairs, drywall, flooring, fencing, decking, insulation, paint, siding, tile, and reference tables. IRC span tables and code checks built in. Pair a Bosch GLM 165-27CGL and shoot a total rise, a room length, a rafter run — the number drops straight into the calculator. No typing. No transposing. Quicker inputs. Shorter workdays. Every calculation saves to your project.
Full access to all 26 carpentry calculators.
Download for iOSBlock count, concrete volume, rebar, mortar, grout, footings, and curing — one app.
10 calculators for masonry and concrete work. Stop doing bag math in your head on the jobsite. Every calculation saves to your project.
No account required. No credit card. Just download and go.
Download for iOSKnow your numbers before you bid. Markup, margin, labor burden, and material volume.
5 estimating calculators that help you price jobs correctly. Understand the difference between markup and margin. Know your true labor cost. Every calculation saves to your project.
No account required. No credit card. Just download and go.
Download for iOSFeet-inch-fraction math, unit conversions, and trade-specific lookups.
8 converters covering every unit you encounter on a jobsite. Feet-inch-fractions, metric, temperature, pressure, area, volume, trade units, and energy cost. Every conversion saves to your project.
No account required. No credit card. Just download and go.
Download for iOS