SEER / EER Rating Calculator
Calculate the Seasonal Energy Efficiency Ratio (SEER) and Energy Efficiency Ratio (EER) for air conditioning and heat pump systems. Convert between SEER and EER, or compute ratings from cooling output and power input.
Mode 1 — Compute SEER & EER from System Data
Mode 2 — Convert Between SEER and EER
Formulas
EER (Energy Efficiency Ratio)
EER = Cooling Output (BTU/hr) ÷ Power Input (Watts)
Measured at a single steady-state condition: 95°F outdoor / 80°F indoor / 50% RH.
SEER (Seasonal Energy Efficiency Ratio)
SEER = Total Seasonal Cooling Output (BTU) ÷ Total Seasonal Energy Input (Wh)
= [BTU/hr × Operating Hours] ÷ [kWh × 1,000]
Represents performance across a full cooling season with varying temperatures.
SEER ↔ EER Conversion (AHRI 210/240 approximation)
EER ≈ SEER × 0.875
SEER ≈ EER ÷ 0.875
The factor 0.875 accounts for part-load operation and seasonal temperature variation.
Cooling Capacity in Tons
Tons = BTU/hr ÷ 12,000
Assumptions & References
- SEER ↔ EER conversion uses the AHRI Standard 210/240 approximation factor of 0.875, valid for typical residential split systems.
- EER is tested at AHRI standard conditions: 95°F (35°C) outdoor dry-bulb, 80°F (26.7°C) indoor dry-bulb, 67°F (19.4°C) indoor wet-bulb.
- SEER is calculated over a cooling season using a bin-hour temperature distribution (AHRI 210/240-2023).
- U.S. federal minimum SEER standards (as of 2023): 14 SEER (North), 15 SEER (South/Southwest) for residential split systems.
- ENERGY STAR qualification threshold: ≥ 15 SEER / ≥ 12.5 EER (split systems, 2023).
- Annual energy estimate assumes 2,000 operating hours per year and a 1-ton (12,000 BTU/hr) baseline unit.
- SEER2 (2023 DOE standard) uses a higher external static pressure (0.5 in. w.g.) and will yield values ~5% lower than SEER for the same equipment.
- References: AHRI Standard 210/240-2023; DOE 10 CFR Part 430; ENERGY STAR Program Requirements for Central Air Conditioners.