AC Tonnage
& Savings ROI
Calculator
Get a climate-adjusted tonnage recommendation and see exactly how many months it takes for a 5-star inverter AC to pay for itself through electricity savings.
Room & Usage Details
Fill in the details below for an accurate, climate-adjusted recommendation
Room Dimensions
City / Climate Zone
Floor Level
Sunlight Exposure
Occupants
Found your AC size? Now calculate exactly how much it will cost per month using BEE 2026 ISEER ratings.
Why 1.5 Ton is the Sweet Spot for Indian Bedrooms
India's average bedroom is 120–160 sq.ft — squarely in 1.5-ton territory. Going to 2-ton for a 150 sq.ft room is a waste: you pay more upfront, consume more electricity, and lose humidity control. Going to 1-ton means the compressor runs non-stop in summer, spiking bills and wearing out the unit faster.
The "Heat Load Calculation" used by HVAC engineers (BTU/hr method) consistently lands medium Indian bedrooms in the 1.5T zone when you factor local climate, BEE star label, and ISEER rating.
150 sq.ft Sweet Spot
Most Indian bedrooms (10×15 ft) fall in the 1.5-ton range — not too much, not too little.
Inverter Efficiency Win
A 1.5T 5-star inverter consumes as low as 1.05 kW at optimal load — 30% less than a 2-ton unit cooling the same space.
Cost Per Cooling BTU
Buying 1.5T costs ₹10,000–15,000 less than 2T. At 8h/day, you save ₹5,000–8,000 annually in electricity.
Humidity Control
Right-sized ACs dehumidify better. An oversized AC short-cycles (frequent on-off), leaving your room feeling clammy.
Expert Tip: Inverter vs Fixed Speed — The Real Maths
Inverter ACs save 30% more power only if used for more than 4 hours daily. Below 4 hours, the compressor doesn't get enough time to modulate down to efficient speeds — the savings advantage narrows. Our calculator accounts for your daily usage hours to give you an honest ROI estimate. Most Indian summer nights run 6–10 hours, which is why 5-star inverter ACs are almost always the right choice for bedrooms.
AC Tonnage Reference Guide: Room Size vs Cooling Load
| Room Size (sq.ft) | Typical Usage | Recommended Tonnage | Ideal Star Rating | Est. Monthly Bill (8h/day) |
|---|---|---|---|---|
| Up to 120 | Small Bedroom / Study | 1 Ton | 5-Star Inverter | ₹1,100–1,500 |
| 121–160 | Standard Bedroom | 1.5 Ton | 5-Star Inverter | ₹1,600–2,100 |
| 161–220 | Master Bedroom / Hall | 2 Ton | 5-Star Inverter | ₹2,200–2,900 |
| 221–300 | Large Living Room | 2.5 Ton | 5-Star Inverter | ₹3,000–3,800 |
| Top Floor +15% | Add floor adjustment | +0.25–0.5 Ton | Same recommendation | Bill rises proportionally |
Frequently Asked Questions
AC buying, sizing & efficiency — answered by experts
Most modern 5-star ACs have S-P-C (Stabilizer Free Operation) built-in, typically rated for 160–264V operation. However, a dedicated voltage stabilizer is still recommended for areas with high voltage fluctuations (common in rural India, Tier-2/3 cities). A V-Guard or Microtek stabilizer (₹1,500–2,500) is cheap insurance for a ₹50,000+ appliance.
Calculations use ASHRAE heat load methodology with BEE India climate adjustments. ROI estimates based on ISEER 3.5 (3-star) vs 5.0 (5-star) at ₹7/unit. Actual bills vary by DISCOM tariff, usage pattern, and insulation. Always consult a certified HVAC technician for final installation sizing.