Free HVAC Calculators & Engineering Tools — UnitsKit.com

UnitsKit gives you 130+ free professional calculators and unit converters. Every tool is instant, accurate, and mobile-friendly. No sign-up. No fees. No ads blocking your results.

HVAC Refrigerant PT Charts — Built for Technicians

Our refrigerant pressure temperature charts cover R410A, R454B, R22, R32, R134a, R404A, R407C, and R507. Each PT chart includes a live lookup tool, full data table from -40°F to 160°F, and a complete charging guide. The R454B chart is especially important in 2026 — this refrigerant is now replacing R410A in all new systems under the AIM Act.

HVAC Sizing — Get It Right the First Time

Undersized systems struggle on hot days. Oversized systems short-cycle and fail to dehumidify. Our cooling load calculator, AC tonnage calculator, and HVAC load calculator use proven industry formulas. They help contractors and homeowners size systems correctly before buying.

Energy Efficiency — Save Money Every Month

Energy costs are rising. Our SEER2 calculator navigates the new 2023/2025 efficiency standards. Our heat pump vs gas heating calculator compares real running costs. Our AFUE calculator shows furnace upgrade payback. And our kWh cost calculator breaks down electricity bills appliance by appliance.

Unit Converters for Engineering Work

Engineering crosses between unit systems constantly. Pressure in PSI and bar. Temperature in Fahrenheit and Celsius. Our converters are two-way, instant, and include full reference tables. No more mental math on the job site.

All calculators use industry-standard formulas. Results are for estimation purposes. Always verify critical work against manufacturer specifications and local codes.