Engineering Calculators for Field Work

Free, no-login, mobile-friendly calculators built for HVAC technicians, welders and fabricators, marine engineers, oilfield and mining crews, and data-center operators. Each tool cites its source — ASHRAE, ACCA, ABYC, API, NEC, Uptime Institute — so you can show your math on the job.

Calculators

Browse by discipline

HVAC & Thermal

Welding & Fabrication

Marine & Offshore

Oil & Gas / Mining

Data Center

Take the toolkits offline

Every category has a matching iOS companion app. Same calculators, saved history, no ads, no login — useful on rooftops and in engine rooms where the browser signal drops.

Works offline on iOS

HVAC Toolkit — load, charge, refrigerant in your pocket

Superheat, subcool, Manual J, duct sizing, CFM per ton. Saves your last 10 readings. No login, no ads.

📱 Get HVAC Toolkit on the App Store

Works offline on iOS

Welding & Sheet Metal Toolkit — bend allowance, heat input, K-factor

Sheet metal bends, weld heat input, coating DFT, press tonnage. Save profiles per material. No login, no ads.

📱 Get Welding & Sheet Metal Toolkit on the App Store

Works offline on iOS

Boat & Marine Engine Toolkit — hull, anchor, prop

Hull speed, anchor scope, bilge pump sizing, propeller slip, bollard pull. Useful at the dock with no signal.

📱 Get Marine Toolkit on the App Store

Works offline on iOS

Oilfield, Drilling & Blast Calc — API 5CT on site

Casing burst, drill string weight, pit slope, weir flow, blast pattern. Built for wellsite and mine bench use.

📱 Get Oil & Gas Toolkit on the App Store

Works offline on iOS

Data Center Engineer Toolkit — PUE, UPS, PDU

PUE, rack density, raised floor load, UPS runtime, PDU load balance. NEC ampacity table included.

📱 Get Data Center Toolkit on the App Store

CalcSpec calculators are estimators for qualified professionals. Results do not replace manufacturer specifications, code-compliant design documents, or the judgment of a licensed engineer or contractor.