Heating Calculators

Heating calculators help HVAC engineers determine equipment capacity, fuel input requirements, and discharge air temperatures for heating systems. This collection includes tools for calculating BTU output from airflow and temperature rise, converting between input and output BTU ratings using combustion efficiency, sizing gas-fired heaters, and evaluating heat pump performance at various outdoor conditions. These calculators apply the standard air heating formula and efficiency factors used throughout the industry so results align with manufacturer specifications and code requirements. Use them during equipment selection to verify a heater can deliver the required thermal output, during plan review to confirm nameplate ratings match design loads, or during commissioning to validate measured temperature rise against the original design.