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
