# FieldFormula — Offline Trade Calculators > Offline Trade Calculators (iPhone/iPad app by 艳明 齐.) - Source: https://appshunter.io/ios/app/fieldformula/id6810904869 (this page in markdown: same URL + `.md`) - Developer: [艳明 齐](https://appshunter.io/developer/6809849616) - Category: Reference - Price: Free (on sale, was $0.99) - Age rating: 4+ - Requires: iOS 17.0 · 3 MB - Languages: American English, French (France), German (Germany), Italian, European Portuguese, European Spanish - Released: 2026-09-19 - Data updated: 2026-10-24 ## What is FieldFormula? Everyday trade math, ready when you need it. FieldFormula brings building, woodworking, electrical, HVAC and plumbing reference calculations to iPhone and iPad. Choose a trade pack, enter your measurements and use Show formula to review the calculation. No registration, login or internet connection is required for the core tools. 11 TOOLS, TWO TRADE PACKS BUILDING, RENOVATION & WOODWORKING • Area: multiply length by width for rectangular floors, walls or roof sections. • Concrete volume: use length, width and thickness, with an entered waste allowance. • Paint quantity: estimate from area, coverage per gallon or liter, coat count and waste allowance. • Lumber: calculate board feet from Imperial dimensions or timber volume in cubic meters. ELECTRICAL • Ohm's law: calculate resistance from voltage and current. • Electrical power: estimate single-phase apparent power and real power using an entered power factor. • Voltage drop: estimate volts and percentage drop for two conductors using current, one-way length and resistance per unit length. HVAC & PLUMBING • Cooling load: multiply area by your entered load factor for a preliminary starting estimate. • Airflow: estimate sensible-load airflow from the load and temperature difference, in CFM or m³/h. • Flow rate: divide collected volume by elapsed time, in gal/min or L/min. • Pipe slope: calculate the percentage and rise-to-run ratio from entered rise and run. MEASURE, CHECK, KEEP A LOCAL RECORD • Work with Metric or Imperial units, with units shown beside each input. • Enter decimal or fractional measurements, such as 3.5 or 1/2. • Review results alongside their formulas and reference assumptions. • Save selected calculations to local history with the tool, date, units and result. • Use portrait or landscape layouts on iPhone and iPad. Unfinished numeric input is retained when the layout changes. • Choose English, Italian, Portuguese, French, Spanish or German in the app. ON-DEVICE WORKFLOW Calculations run on your device and history is stored locally on that device. This iPhone/iPad version can generate JSON/CSV history files and PDF calculation reports in the app's own storage, displaying the saved path. It does not offer an external share sheet or a save-destination picker. REFERENCE ESTIMATES These tools provide starting values for review. They do not provide engineering design approval, professional certification or automatic code compliance. Check local codes, manufacturer data, permits and professional suitability before using a result for construction or energized work. Choosing units or a reference region does not establish compliance. Support: levinghost@outlook.com ## Is FieldFormula safe? Not enough ratings yet to assess FieldFormula. ## Is FieldFormula legit? FieldFormula appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for FieldFormula is 65 out of 100 points across 7 verification signals from App Store and developer data. ## Version history (last 2 releases) ### 1.2 — 2026-10-23 Refined full-screen layouts for iPhone and iPad, including portrait and landscape support. Improved number entry and retention of unfinished input across layout changes. More reliable local history imports and clearer localized calculation details. ### 1.1 — 2026-09-19 No release notes. ## More apps by 艳明 齐 - [ChipDial](https://appshunter.io/ios/app/chipdial/id6809970441) - [CreatorCalc: Shoot Planner](https://appshunter.io/ios/app/creatorcalc-shoot-planner/id6814385223) All apps by 艳明 齐: https://appshunter.io/developer/6809849616 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-24.*