Lien - Trades Calculator

18 trade calculators — electrical, plumbing, HVAC, carpentry. Offline, with projects + PDF export.

Every trade calculation. One app. Forever offline.

Lien bundles the everyday calcs that electricians, plumbers, HVAC techs, and carpenters reach for on the truck — in a clean, fast iOS app that works without signal.

WHAT'S INSIDE (18 calculators)

• Electrical (6): wire size, voltage drop, conduit fill, box fill, motor FLA, service load.
• Plumbing (4): friction loss, fixture units, drain size, water-heater sizing.
• HVAC (4): BTU sizing, duct size, SEER cost, composite R-value.
• Carpentry (4): cut list, beam span, rafter, stairs.

MORE THAN A CALCULATOR

• Save calculations and group them into named Projects, then export a clean PDF for the inspector or the client.
• Reference tables bundled offline: NEC ampacity, conduit fill, pipe sizing, R-values, fastener guide.
• Pick your code region (US NEC, UK BS 7671, AU/NZ AS 3000); tables and formulas calibrate to it.
• 100% on-device. No accounts, no cloud, no data sync. Built dark-mode-first for job-site readability.

FREE TIER

• The full Electrical trade (6 calculators) and up to 3 saved calculations — free, forever.

LIEN PRO (auto-renewing subscription)

• Unlocks all 4 trades (18 calculators), unlimited saved calculations, and Projects with PDF export.
• $9.99/month or $59.99/year (about 3 months free on the yearly plan).
• Payment is charged to your Apple Account at purchase confirmation. The subscription renews automatically for the same price and period unless you turn off auto-renew at least 24 hours before the end of the current period. Manage or cancel anytime in Settings > Apple Account > Subscriptions.

DISCLAIMER Lien is a calculator. Always verify results against the current local code in force (NEC, IPC, IMC, IBC, or the regional equivalent). Lien is not a licensing or certification authority.

Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://lien.uptrail.ai/privacy