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Structural Span & Beam Sizing Calculator

Joist spans, rafter spans, headers, beams, and deck sizing from AWC NDS tables.

$7.99. Once. Forever. No subscription. No account. Works offline.

Coming Soon to the App Store

Structural Span & Beam Sizing Calculator is currently in development and will be available on the App Store soon. Enter your email to be notified the moment it launches.

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What’s Inside

Free Features

  • Lumber Span Tables (Floor & Ceiling Joists) — Species (Douglas Fir-Larch, Hem-Fir, Southern Pine, Spruce-Pine-Fir), grades (#1, #2, Select Structural), sizes (2x6 through 2x12), spacings (12”, 16”, 19.2”, 24” o.c.), load conditions (30 psf LL / 10 psf DL for floors; 10 psf LL / 10 psf DL for ceilings). Per AWC NDS 2021 / IRC 2021.
  • Rafter Span Tables — Same species/grade matrix with slope adjustments and snow load variants (20, 30, 50 psf ground snow). Max rafter span with ridge beam sizing recommendation.
  • Simple Beam Load Calculator — Span, tributary width, dead/live load (psf). Outputs total load (lbs), uniform load (plf), max moment, required section modulus. Cross-reference to span table results automatically.
  • Unit Handling — All inputs accept feet-inches-fractions (e.g., “12’ 6½""). No decimal guessing on the jobsite.

Full Unlock ($7.99 one-time)

  • Header & Beam Sizing — Opening width, floors above (0/1/2), load bearing condition. Species selection. Outputs minimum header size (e.g., “4x10 or doubled 2x10”) per IRC Table R602.7 with LVL equivalents.
  • Deck Beam & Post Sizing — Per AWC DCA6 Prescriptive Residential Deck Construction Guide. Beam span, joist span, deck load. Outputs beam size, post size, post spacing.
  • Accelerometer Roof Pitch & Floor Level Meter — Point phone at any roof surface and read pitch live in both X:12 format (6:12) and degrees (26.6°) simultaneously. Tap Lock to auto-fill the rafter calculator. Digital bubble level for floor/beam level checks. No physical pitch gauge needed — your iPhone is now a $30 tool.
  • Voice Input — “Twelve feet six and a quarter,” “two by ten,” “sixteen inches on center,” “thirty psf” — hands-free dimension entry while holding measuring tape and lumber.
  • Save & History — Save calculation snapshots with project labels. On-device PDF export with inputs, outputs, code citations. No cloud.
  • Code Citations — Every result displays the NEC/IRC table reference (e.g., “Per IRC Table R802.4.1”). Cite code directly to inspectors and permit applicants.

Why We Built This

Span Calc, the official AWC (American Wood Council) app, has a 2.9-star rating with only 15 reviews. The official authoritative tool is broken. Users report:

  • “Dropdowns do not work with the new update”
  • “Locks up after upgrades”
  • The app is 176MB for a reference tool that should be lightweight

There is no credible, modern, iOS-native span and beam sizing app. Contractors, framers, and inspectors fall back to paper span books and web calculators.

FieldLab’s answer: $7.99 once. Modern SwiftUI native design (not a 2014 web wrapper). Works 100% offline with bundled NDS tables. Never breaks from iOS updates. Accelerometer pitch meter (read existing roof pitch with your phone — the official app cannot do this). Voice input for gloved hands. Zero account, zero data sent anywhere.

Built for the Jobsite

  • Bright Light Optimized — Framers work outdoors in bright sunlight. Light mode is primary. High-contrast UI readable in direct sun. Full dark mode support for covered work.
  • Glove-Friendly — 48pt minimum tap targets. Voice input for hands-free entry while holding tape measures and lumber.
  • Works Offline — Zero internet required. No account. No login. Your data never leaves your phone. NDS tables are bundled and always available.
  • Reliability — Built with modern SwiftUI. Never breaks from iOS updates. Bundled data is always your fallback. The official AWC app locks up after upgrades — we won’t.

The Official App Is Broken. We Built a Better One.

Span Calc (official AWC app) is free but broken — 2.9 stars, users report dropdowns freezing and lockups after iOS updates.

Structural Span & Beam Sizing Calculator costs $7.99. Works offline. Never breaks. Always responsive. That’s it.

We will never charge a subscription. Read why →

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