Free Tools/AC Tonnage Calculator

AC Tonnage Calculator (India)

Get the right AC ton size for any room — bedroom, living room, kitchen or office. Adjusted for hot Indian climate. No signup, instant result.

Quick answer

For Indian hot climate: 1 ton AC = up to 130 sqft room · 1.5 ton = 130–200 sqft · 2 ton = 200–300 sqft. Always size up if your room is west-facing, top-floor, or used as a kitchen.

Room details

Recommended size

1.5ton
Required for your room
Room volume1,200 cu ft
Required BTU15,000 BTU
Use adjustment+10%
Recommended AC1.5 ton

How AC tonnage is calculated

AC capacity is measured in tons of refrigeration. One ton equals 12,000 BTU per hour — roughly the cooling needed to remove the heat from one ton of ice melting over 24 hours. The right size depends on room volume, use type, climate and number of occupants.

Formula: Tonnage = (Length × Width × Height × BTU/cu ft × Use factor + 600 BTU per person) ÷ 12,000

How to use this calculator

  1. Measure your room's length, width and ceiling height in feet. Standard Indian rooms are 10 ft tall.
  2. Pick the room use — kitchens generate the most heat (cooking + appliances), so they need ~30% more cooling than a bedroom of the same size.
  3. Pick the climate — Rajasthan, top-floor flats and west-facing rooms in summer need more BTU per cubic foot than coastal Mumbai or Bangalore.
  4. Enter the typical number of people using the room. Each person adds about 600 BTU of body heat.
  5. Read the recommended ton size (rounded up to the nearest 0.5 ton, since AC units are sold as 0.75, 1, 1.5, 2 ton).

Quick reference for India

Room sizeBedroomLiving / kitchen
Up to 100 sqft0.75 ton1.0 ton
100–150 sqft1.0 ton1.5 ton
150–250 sqft1.5 ton1.5–2.0 ton
250–400 sqft2.0 ton2.0–2.5 ton
400+ sqft2.5–3.0 tonMultiple units recommended

Why undersizing & oversizing both fail

Undersized AC runs continuously without ever reaching the set temperature — your electricity bill spikes and the compressor wears out faster.

Oversized AC cools the room too fast, switches off, and switches back on repeatedly — short-cycling that fails to remove humidity, leaving the room cool but clammy. Always size to your actual room volume + use + climate.

Frequently asked questions

What size AC do I need for a 150 sqft bedroom?
A 150 sqft bedroom (10×15 ft) with 10 ft ceiling needs roughly 1 ton AC in moderate climate or 1.5 ton in hot Indian summer conditions, especially if the room is on a top floor or west-facing.
Is 1 ton AC enough for 200 sqft room?
1 ton AC is suitable for rooms up to about 130 sqft in hot Indian climate. For 200 sqft you'll typically need 1.5 ton, especially if the room gets direct sun or has multiple occupants.
How is AC tonnage calculated?
AC tonnage is calculated by multiplying room volume (length × width × height in feet) by approximately 25 BTU/cubic foot for hot climate, then dividing by 12,000 (1 ton = 12,000 BTU). Adjustments are added for room use, sun exposure and number of people.
Should I size up or down for AC?
Always size up to the next half-ton if your calculated requirement falls between standard sizes. An undersized AC runs constantly without cooling properly; an oversized AC short-cycles and removes humidity poorly.
Does ceiling height matter?
Yes — AC sizing is based on room volume, not just floor area. A 150 sqft room with a 12 ft ceiling has 20% more air to cool than the same room with a 10 ft ceiling. Always measure ceiling height when calculating.
What about kitchens?
Kitchens generate substantial heat from cooking, refrigeration and appliances. Bump the calculator's room-use selector to Kitchen — this adds 30% to the requirement vs. a bedroom of the same size.

Related calculators

Lighting Lumens

How many lumens a room needs

Paint Calculator

Litres needed by wall area

Standard Dimensions

Door, window, cabinet sizes

Want all 11 calculators in your pocket?

Download InteriorOS — calculators bundled with project management, finance and CRM, built for Indian interior design studios.

Get the app