How Much Ton AC Do I Need?Room Size to Tonnage Calculator Guide 2026
Find the exact AC tonnage for your room. Use our simple formula, room dimension lookup table, and heat load factors to pick the right size for any Indian home.
Reviewed by Sulaiman Sekh
HVAC Technician · 8+ Years · 200+ Installations
Quick Answer
Use this simple rule for Indian homes: 1 ton per 120 sq ft of room area. Measure length × width in feet, divide by 120, and round up to the nearest half-ton. Add 0.5 ton for top floors, direct sunlight, or ceilings above 10 ft. A 10 × 12 ft (120 sq ft) bedroom needs 1 ton. A 12 × 15 ft (180 sq ft) master bedroom needs 1.5 ton.
Formula: (Length × Width) ÷ 120 = Tons
Measure your room in feet, multiply length by width, divide by 120, then round up to the nearest half-ton. This is the standard Indian AC sizing rule.
1 ton per 120 sq ft is the base rule
A 120 sq ft room needs 1 ton. A 180 sq ft room needs 1.5 tons. A 300 sq ft room needs 2.5 tons. Always round up, never down.
Add 0.5 ton for each heat load factor
Top floor, west-facing, high ceilings above 10 ft, 4+ people, or large electronics all increase demand. Stack these factors and add accordingly.
When in doubt, size up
An oversized AC cools quickly and cycles off. An undersized AC runs non-stop, consumes more electricity, and never reaches comfort.
25–30 BTU per sq ft for Indian conditions
This rule confirms the ÷120 formula. A 150 sq ft room needs 3,750–4,500 BTU, which a 1.5 ton AC (18,000 BTU) handles easily.
Quick Answer: How Much Ton AC Do I Need?
Use this simple rule for Indian homes: 1 ton per 120 sq ft of room area. Measure length × width in feet, divide by 120, and round up to the nearest half-ton. Add 0.5 ton for top floors, direct sunlight, or ceilings above 10 ft. A 10 × 12 ft (120 sq ft) bedroom needs 1 ton. A 12 × 15 ft (180 sq ft) master bedroom needs 1.5 ton.
Up to 120 sq ft
1 Ton
120–180 sq ft
1.5 Ton
180–300 sq ft
2 Ton
300–400 sq ft
2.5 Ton
AC Tonnage by Room Dimensions
Look up your exact room size to find the right AC tonnage instantly.
| Room Dimensions | Area (sq ft) | Recommended AC | Notes |
|---|---|---|---|
| 8 × 10 ft | 80 sq ft | 0.8 – 1 Ton | Small bedroom, study room |
| 10 × 10 ft | 100 sq ft | 1 Ton | Standard small bedroom |
| 10 × 12 ft | 120 sq ft | 1 Ton / 1.2 Ton | Max for 1 ton — use 1.2 ton if sunny |
| 10 × 12 ft (top floor) | 120 sq ft | 1.5 Ton | Roof heat pushes requirement up |
| 12 × 12 ft | 144 sq ft | 1.5 Ton | Master bedroom standard size |
| 12 × 15 ft | 180 sq ft | 1.5 Ton / 2 Ton | Use 2 ton if west-facing or top floor |
| 13 × 16 ft | 208 sq ft | 2 Ton | Large bedroom or small living room |
| 15 × 18 ft | 270 sq ft | 2 Ton | Medium living room |
| 16 × 20 ft | 320 sq ft | 2.5 Ton | Large living room or drawing room |
| 20 × 20 ft | 400 sq ft | 3 Ton | Hall, banquet, or office space |
Don't see your exact size? Use the formula: (Length × Width) ÷ 120 = Required Tons. Round up to the nearest half-ton. Then add 0.5 ton for each heat factor (top floor, west-facing, high ceiling, 4+ people).
Heat Load Factors — Add 0.5 Ton For Each
Standard sizing assumes a plain room. These factors increase cooling demand significantly.
Top Floor
+0.5 TonRoof absorbs sun heat all day. Adds 25–35% load. Always add 0.5 ton.
West-Facing Wall/Window
+0.5 TonAfternoon sun directly heats the room. Adds 20–30% load.
Ceiling > 10 ft
+0.2–0.5 TonMore air volume to cool. Add 0.2 ton per extra foot above 10 ft.
4+ People in Room
+0.2–0.3 TonEach person emits ~600 BTU/hr. 4 people = 2,400 BTU extra.
Large Electronics
+0.2 TonTV, desktop, gaming PC add 500–2,000 BTU of heat.
Poor Insulation
+0.2–0.3 TonOld windows, thin walls, gaps under doors. Adds 15–25% load.
Example Calculation
Room: 12 × 14 ft = 168 sq ft. Base requirement: 168 ÷ 120 = 1.4 tons → round up to 1.5 ton.
- • Top floor: +0.5 ton → 2.0 ton
- • West-facing window: +0.5 ton → 2.5 ton
- • 10.5 ft ceiling: +0.2 ton → 2.7 ton
Final recommendation: 2.5 ton AC (or a 2 ton inverter with high ambient performance)
Related Sizing Guides & Tools
Explore detailed room size coverage and interactive calculators.
1 Ton AC Room Size
Coverage for 80–120 sq ft rooms
1.5 Ton AC Room Size
Coverage for 120–180 sq ft rooms
2 Ton AC Room Size
Coverage for 180–300 sq ft rooms
2.5 Ton & 3 Ton AC Room Size
Coverage for 300+ sq ft spaces
AC Room Size Chart
Complete tonnage-to-room reference
Room Size Calculator
Interactive tonnage finder
1 Ton vs 1.5 Ton AC
Which size for your bedroom?
1.5 Ton vs 2 Ton AC
When to upgrade to 2 ton
What Is 1 Ton AC?
Understanding BTU and tonnage
Frequently Asked Questions — How Much Ton AC Do I Need?
How much ton AC do I need for a 10×10 room?
How much ton AC do I need for a 10×12 room?
How much ton AC do I need for a 12×12 room?
How much ton AC do I need for a 12×15 room?
How much ton AC do I need for a 200 sq ft room?
What is the formula to calculate AC tonnage for a room?
How many BTU per sq ft do I need for AC in India?
Does ceiling height affect AC tonnage calculation?
Calculate Your Exact AC Size Now
Use our interactive calculator for an instant tonnage recommendation based on your room dimensions, floor level, and sunlight exposure.
Frequently Asked Questions
Straight answers to common questions.
How much ton AC do I need for a 10×10 room?
A 10 × 10 ft room is 100 sq ft. You need a 1 ton AC. Using the formula: 100 ÷ 120 = 0.83 tons, round up to 1 ton. If the room is on the top floor or gets direct sunlight, consider a 1.2 ton AC instead.
How much ton AC do I need for a 10×12 room?
A 10 × 12 ft room is 120 sq ft. You need a 1 ton AC as the base. However, if the room is on the top floor, west-facing, or has a ceiling above 10 ft, upgrade to 1.2 or 1.5 ton. For standard conditions on the ground floor, 1 ton is sufficient.
How much ton AC do I need for a 12×12 room?
A 12 × 12 ft room is 144 sq ft. You need a 1.5 ton AC. Using the formula: 144 ÷ 120 = 1.2 tons, round up to 1.5 ton. This is the most common master bedroom size in India, and 1.5 ton is the perfect match.
How much ton AC do I need for a 12×15 room?
A 12 × 15 ft room is 180 sq ft. You need a 1.5 ton AC minimum, or 2 ton if the room is on the top floor, west-facing, or has high ceilings. Using the formula: 180 ÷ 120 = 1.5 tons exactly. This is the upper limit for a 1.5 ton unit.
How much ton AC do I need for a 200 sq ft room?
For a 200 sq ft room, you need a 2 ton AC. Using the formula: 200 ÷ 120 = 1.67 tons, round up to 2 tons. A 1.5 ton AC would run continuously in this space without ever reaching comfortable temperatures.
What is the formula to calculate AC tonnage for a room?
The simple formula for Indian homes is: Tons = (Length in ft × Width in ft) ÷ 120. Then round up to the nearest 0.5 ton. Add 0.5 ton for each major heat factor: top floor, west-facing, ceiling above 10 ft, or 4+ occupants. Example: 14 × 16 ft room = 224 sq ft. 224 ÷ 120 = 1.87 tons → round up to 2 tons. Top floor adds 0.5 → final = 2.5 tons.
How many BTU per sq ft do I need for AC in India?
In Indian conditions, you need approximately 25–30 BTU per square foot. For a 150 sq ft room, this means 3,750–4,500 BTU. A 1.5 ton AC provides 18,000 BTU, which covers 150 sq ft comfortably with headroom for hot days.
Does ceiling height affect AC tonnage calculation?
Yes. Standard AC sizing assumes 9–10 ft ceilings. Every foot above 10 ft adds approximately 10% more air volume to cool. A room with 12 ft ceilings needs 20% more capacity. For a 150 sq ft room with 12 ft ceilings, calculate as 150 × 1.2 = 180 sq ft equivalent, which needs 1.5 ton instead of 1.2 ton.
Expert Review by Sulaiman Sekh
HVAC Technician · 8+ Years Experience · Fact-checked & field-tested
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