AC efficiency ratings like SEER, EER, and ISEER tell you how much cooling you get per unit of electricity. Higher numbers mean better efficiency and lower bills. Here’s a simple guide to what each rating means and which one matters for you.
EER: Energy Efficiency Ratio
EER measures cooling output (BTU/h) divided by power input (watts) at a fixed condition—usually 35°C outdoor and 27°C indoor. It’s a snapshot at one operating point.
EER Formula
EER = Cooling Capacity (BTU/h) ÷ Power (Watts). Example: 12,000 BTU ÷ 1,200 W = 10 EER.
SEER: Seasonal Energy Efficiency Ratio
SEER is used mainly in the US. It averages efficiency over a full cooling season with varying temperatures. SEER is typically higher than EER because it includes part-load and low-ambient conditions.
| Rating | Typical SEER | Relative Efficiency |
|---|---|---|
| Basic | 13–14 | Standard |
| Good | 15–16 | Better |
| High | 18–22 | Premium |
ISEER: Indian Seasonal Energy Efficiency Ratio
ISEER is India’s standard, designed for Indian climate and usage. It considers multiple temperature bins (25°C to 43°C) and part-load operation. ISEER is what you see on Indian AC labels and star ratings.
| Star Rating | ISEER Range | Efficiency Level |
|---|---|---|
| 3-Star | 3.3 – 3.5 | Minimum standard |
| 4-Star | 3.7 – 4.0 | Good |
| 5-Star | 4.5+ | Best |
Which Rating Matters in India?
In India, focus on ISEER and star ratings. They reflect local conditions and are used for BEE (Bureau of Energy Efficiency) labelling. SEER and EER appear on imported or US-spec units.
How Higher Ratings Save Money
- Higher ISEER = more cooling per unit of electricity.
- A 5-star AC (ISEER ~4.5) can use 15–25% less power than a 3-star (ISEER ~3.3) for the same cooling.
- Over 5–10 years, the savings often exceed the price difference.
Use Our Tools
Plug your AC’s capacity and ISEER into our AC Energy & Cost Calculator to see estimated running cost. Read 3-star vs 5-star AC for a payback comparison and 10 efficiency questions before buying.
FAQs
What is a good ISEER for AC in India?
4.5 or higher (5-star) is excellent. 3.7–4.0 (4-star) is good. 3.3–3.5 (3-star) meets minimum standards.
Can I compare SEER and ISEER directly?
Not directly. They use different test conditions. Use ISEER for Indian ACs, SEER for US imports.
Does higher EER mean lower electricity bill?
Yes. Higher EER (or ISEER) means more cooling per watt, so lower power draw for the same comfort.
Why do inverter ACs have higher ISEER?
Inverters run at part load efficiently. ISEER tests part-load performance, so inverters score better.
Is 5-star AC always better than 3-star?
For efficiency, yes. For value, it depends on usage. Heavy users benefit more from 5-star. See our 3-star vs 5-star guide.
Where do I find ISEER on my AC?
On the BEE energy label, product brochure, or online listing. Look for "ISEER" or "Seasonal Efficiency."
Conclusion
ISEER and star ratings are your main guides in India. Higher ratings cost more upfront but save over time. Use our calculator and guides to make an informed choice.