Best Framing & Carpentry Calculator Apps for iPhone 2026
The Best Framing & Carpentry Calculator Apps for iPhone in 2026
Carpenters and framers live in feet, inches, and fractions. A two-inch difference in stair rise throws off the entire staircase. A miscalculation in rafter length costs hours of rework. The best calculators aren’t the fanciest — they’re the ones that handle framing math accurately and fast.
Construction Master Pro moved to a $19.99/month subscription in 2025. For carpenters who owned the app for years, losing the one-time purchase option stung. But alternatives exist, and most are cheaper.
This guide covers the best framing calculator apps in 2026, what each does well, and which one fits your workflow.
What Carpenters and Framers Calculate Most
Daily calculations:
- Stair rise and run (IRC code compliance)
- Board feet for lumber ordering
- Stud spacing and count
- Roof pitch and rise
Weekly or project-dependent:
- Rafter length calculations
- Compound miter angles
- Joist span lookups
- Roof load calculations
A good framing calculator nails stair calculations and feet-inch-fraction math. Everything else is bonus.
The Framing Calculator Options in 2026
FieldLab Framing & Carpentry Calculator — $9.99 One-Time
FieldLab’s Framing & Carpentry Calculator launches native SwiftUI with dark mode, full offline access, and no subscription.
What it covers:
- Stair rise and run with IRC code compliance checking (7” to 8” rise, 10” to 11” run)
- Board feet calculations (dimensional lumber volume)
- Stud spacing and count for walls and rafters
- Roof pitch conversion (degrees, percentages, rise-over-run)
- Feet-inch-fraction math (add, subtract, multiply, divide with 1/16” precision)
- Quick reference for common lumber sizes and spacing codes
UI highlights: Dark mode optimized for on-site work, Dynamic Type for readability, and offline operation everywhere.
Price: $9.99 one-time Dark mode: Yes, by default Offline: Yes
Limitations: Rafter calculations (beyond simple rise) and compound miter angles aren’t in the current version. Both are on the roadmap.
Our bias: We built this. The math is solid, but we’re listing competitors fairly.
Construction Master Pro — $19.99/Month
Construction Master Pro is Calculated Industries’ flagship tool, covering stair calculations, rafter math, board feet, and general construction. With a 4.9-star rating, it’s widely used by framers who trust its calculations.
The problem is the subscription. What used to cost $25 as a one-time purchase now costs $240 per year. For a tool that calculates the same mathematical relationships it did 20 years ago, the recurring cost is hard to justify.
Price: $19.99/month (or $240/year) Features: Comprehensive (stair, rafter, board feet, compound angles) Dark mode: No Offline: Yes Annual cost: $240 minimum
BuildCalc — $24.99 One-Time
BuildCalc is a veteran framing calculator with a small but loyal user base. One-time purchase at $24.99 covers stair rise/run, rafter calculations, feet-inch math, and general construction math.
The UI dates to roughly 2010 — it’s functional but hasn’t been modernized. With only 147 App Store reviews (4.7 stars), BuildCalc has a narrow but devoted following. Some carpenters have used it for 15+ years.
Price: $24.99 one-time Features: Stair, rafter, board feet, general math Dark mode: No Offline: Yes Rating: 4.7 stars (147 reviews)
Carpenter Calc — $9.99 One-Time
Carpenter Calc is a lightweight option focusing on basic framing math: feet-inch conversions, board feet, lumber calculations, and simple stair estimates.
It doesn’t include detailed stair calculators with IRC compliance checking or rafter geometry. With only 62 reviews (4.5 stars), it’s less established than BuildCalc or Construction Master Pro, but it’s cheaper.
Price: $9.99 one-time Features: Basic framing math, board feet, simple stair estimates Dark mode: No Offline: Yes Rating: 4.5 stars (62 reviews)
Free Web Option: BuiltByFieldLab.com Calculators
BuiltByFieldLab.com offers free stair rise-and-run, board feet, and roof pitch calculators in your browser.
The free stair calculator handles the core calculation: given total rise and number of treads, what’s the individual rise and run? It checks IRC compliance and flags violations. For quick estimates on the job site or at the office, it’s accurate and free.
Try the free stair calculator → Try the free roof pitch calculator → Try the free board feet calculator →
Price: Free Features: Stair calculations, pitch conversions, board feet Dark mode: No (browser-dependent) Offline: No
The Price Comparison Table
| App | Price | Stair Calc | Rafter Calc | Compound Angles | Dark Mode | Annual Cost |
|---|---|---|---|---|---|---|
| FieldLab Framing & Carpentry | $9.99 once | ✓ (IRC compliant) | Limited | No | Yes | $0 |
| Carpenter Calc | $9.99 once | Basic | No | No | No | $0 |
| BuildCalc | $24.99 once | ✓ | ✓ | ✓ | No | $0 |
| Construction Master Pro | $19.99/mo | ✓ | ✓ | ✓ | No | $240 |
| BuiltByFieldLab.com (Web) | Free | ✓ (Basic) | No | No | No | $0 |
Detailed Feature Comparison
Stair Rise and Run Calculations
This is the foundation of framing work. Given a total rise (floor to floor) and the number of treads you want, a good stair calculator tells you:
- Individual rise per step
- Individual run (tread depth)
- Whether the result meets code (IRC requires 7” to 8” rise, 10” to 11” run)
FieldLab’s advantage: Explicitly checks IRC compliance and flags violations. If rise is 8.5” (illegal), the app tells you so. BuildCalc and Construction Master Pro calculate accurately but don’t highlight code issues. The free web calculator also checks IRC compliance.
Rafter Calculations
Beyond simple rise, rafter geometry gets complex: cutting the bird’s mouth, calculating run from pitch, finding total rafter length, accounting for overhang.
BuildCalc and Construction Master Pro handle full rafter geometry. FieldLab’s app calculates pitch and rise but doesn’t yet cover the full rafter suite. Carpenter Calc doesn’t include rafter math at all.
If you calculate rafters weekly, BuildCalc ($24.99) or Construction Master Pro ($19.99/month) are safer bets today. If rafter calculations are occasional, FieldLab’s roadmap includes them.
Compound Miter Angles
Crown molding, angled cuts, and geometric trim work require compound angle calculations. Only BuildCalc and Construction Master Pro have this feature.
Most residential carpenters use this occasionally. Commercial framers and finish carpenters use it more regularly. If compound angles are core to your work, BuildCalc or Construction Master Pro is necessary.
Feet-Inch-Fraction Math
All four paid apps handle conversions: 10 feet 3.5 inches = 123.5 inches, etc. Some calculators offer 1/8” precision; others do 1/16”.
FieldLab’s app supports 1/16” fractions (standard for carpentry). BuildCalc and Construction Master Pro are equivalent.
Board Feet Calculations
Lumber is sold by board feet (1 bf = 1” thick × 12” wide × 12” long). Calculating board feet from dimensions is straightforward, but tracking multiple pieces adds complexity.
All four apps do this. No significant advantage to any one.
Dark Mode for On-Site Work
Carpenters work in basements, attics, and dimly-lit construction sites. A bright white calculator screen is a distraction.
Only FieldLab’s app defaults to dark mode. BuildCalc, Carpenter Calc, and Construction Master Pro all ship with light mode. You can force dark mode via iOS system settings, but calculator apps don’t always respect it.
Which App to Choose
Choose FieldLab Framing & Carpentry ($9.99) If:
- You want the cheapest option with no subscription
- Stair calculations and feet-inch math are your main daily work
- You work frequently on dimly-lit sites (dark mode matters)
- You want offline access everywhere
- You prefer a modern, clean interface
- You’re willing to wait for rafter calculations (roadmap)
Choose BuildCalc ($24.99) If:
- You calculate rafters and compound angles regularly
- You’ve used BuildCalc for years and trust it
- You want a one-time purchase without subscriptions
- The older UI doesn’t bother you
- You need the most comprehensive feature set today
Choose Carpenter Calc ($9.99) If:
- You calculate very basic framing math (feet-inch conversions, board feet)
- You don’t calculate stairs with code compliance needs
- You want the absolute cheapest app with offline access
Choose Construction Master Pro If:
- You need the most comprehensive features today and subscriptions are acceptable
- You’ve used Construction Master Pro for years
- Money isn’t the concern
Reality check: You’ll pay $240/year for Construction Master Pro. BuildCalc costs $24.99 forever. FieldLab costs $9.99 forever (and adds rafter calculations later).
Use Free Web Calculators If:
- You calculate stairs infrequently
- You have reliable WiFi/cellular at job sites
- You want to test before buying
- You work on Android (FieldLab apps are iOS-only)
The Rafter Calculation Question
If rafter math is essential to your work today, you have two options:
- BuildCalc ($24.99) — proven, one-time purchase, comprehensive
- Construction Master Pro ($240/year) — most features, but subscription cost
FieldLab’s roadmap includes rafter calculations, but “on the roadmap” means future, not today. If you need rafter math now, BuildCalc is the best value one-time option.
If stair calculations are your main work, FieldLab ($9.99) is unbeatable price-wise today. When rafter calculations launch, you get them for free (no app version to rebuy).
Frequently Asked Questions
Does FieldLab’s app calculate rafter length?
Not yet. It calculates pitch, rise, and run separately, but not the full rafter geometry with bird’s mouth cuts. This is on the roadmap.
Which app is most accurate for stair rise and run?
All paid apps calculate rise and run using the same mathematics. If the total rise and number of treads are identical, results will match. FieldLab’s advantage is explicitly checking IRC compliance — it tells you if the result is legal. The free web calculator also does this.
Can I use these on Android?
FieldLab’s apps are iOS-only. BuildCalc, Carpenter Calc, and Construction Master Pro may have Android versions — check Google Play Store. The free calculators at BuiltByFieldLab.com work on any browser.
Why is Construction Master Pro so expensive now?
Calculated Industries moved to recurring revenue model in 2025. Pressure from investors and private equity favors subscription revenue over one-time purchases. The app does the same calculations it did when it cost $25 to buy once.
Should I buy BuildCalc or wait for FieldLab’s rafter calculations?
If you calculate rafters weekly, buy BuildCalc now. If rafter math is occasional and stair calculations are your bread-and-butter, FieldLab is the safer bet (cheaper, modern UI, will add rafter eventually).
Does dark mode really matter that much?
For on-site framing, yes. Your pupils adjust to darkness; a bright screen re-adapts them to bright mode, making your eyes less effective in low light. It’s a small feature with real productivity impact if you work in basements and attics regularly.
Can I try these apps before buying?
Use the free web stair calculator to verify calculation accuracy. If it matches your known-good stairs, the app will too. All paid calculators use proven formulas with minimal differences.
Will FieldLab charge extra for rafter calculations when they launch?
No. Rafter calculations will be a free update to the $9.99 app. Unlike Calculated Industries (which sometimes charges for new code editions), we include major feature updates at no extra cost.