What size AC for a 500 sq ft room?

A 500 sq ft (≈46 m²) room typically needs a 1.0 to 1.5 ton air conditioner (12,000–18,000 BTU/h), depending on climate zone, insulation quality, ceiling height, and window area. In hot climates with poor insulation, you may need up to 2.0 tons. Use this calculator for a precise estimate.

What is a ton of cooling?

A ton of cooling (also called a refrigeration ton or RT) equals 12,000 BTU/h or approximately 3.517 kW. It represents the amount of heat needed to melt one ton of ice in 24 hours. Residential AC units range from 0.5 tons (window units) to 5.0 tons (central air systems).

How to read AC tonnage charts?

AC tonnage charts match room square footage to recommended tonnage. Find your room area on the chart, then read across to the suggested ton size. For example, 600–900 sq ft typically maps to 1.5 tons, 900–1,200 sq ft to 2.0 tons. Always adjust upward for south-facing rooms, poor insulation, or hot climates.

Is a bigger AC always better?

No. An oversized air conditioner cools the room too quickly without running long enough to dehumidify properly. This causes short-cycling, uncomfortable humidity levels, higher energy bills, and increased wear on the compressor. Proper sizing based on load calculation is always the best approach.

What's the difference between tonnage and BTU?

Tonnage and BTU both measure cooling capacity but in different units. 1 ton = 12,000 BTU/h. Tonnage is commonly used for central AC and heat pump sizing, while BTU/h is used for window units and portable AC. The two are interchangeable — a 2-ton AC provides 24,000 BTU/h of cooling.

AC Size Calculator - What Size Air Conditioner Do I Need?

Input Parameters

Room Area (m²) *

Room Height (m)

Building Type

Room Orientation

Window-to-Wall Ratio (0–1)

0.3 = windows cover 30% of exterior wall area

Summer Outdoor Temperature (°C)

For cooling load calculation

Summer Indoor Temperature (°C)

Insulation Level

Results

Recommended AC Size:

-- tons

Cooling Capacity:

-- BTU/h

Cooling Power:

-- kW (-- W)

Raw Tonnage:

-- tons

Cooling Load per Area:

-- W/m²

Tip: 1 ton of cooling ≈ 12,000 BTU/h ≈ 3.517 kW. Recommended tonnage is rounded up to the nearest 0.5 ton. Select equipment rated at or above the recommended size. Final design should be verified by a qualified HVAC professional.

Common AC Size Reference

Tons	BTU/h	Approx. Area (sq ft)
1.0	12,000	400–600
1.5	18,000	600–900
2.0	24,000	900–1,200
2.5	30,000	1,200–1,500
3.0	36,000	1,500–1,800
3.5	42,000	1,800–2,100
4.0	48,000	2,100–2,400
5.0	60,000	2,400–3,000

About This Calculator

This AC size calculator determines the recommended air conditioner tonnage using the unit-index cooling load method:

Base cooling index per square meter, varying by building type (ASHRAE standard)
Corrections for orientation, insulation level, window-to-wall ratio, and temperature difference
Results in recommended tonnage (rounded to nearest 0.5 ton), BTU/h, and kW
Cooling load per area (W/m²) for quick comparison

Results are for preliminary sizing only. Final equipment selection should be done by a qualified HVAC engineer.

How this AC size calculator works

This tool estimates the cooling capacity needed for your room and converts it to recommended AC tonnage. It starts from a base cooling index per square meter (varying by building type), then adjusts for orientation, insulation, window area, and the indoor-outdoor temperature difference. The final result is converted to tons and rounded up to the nearest standard half-ton size.

Understanding AC Tonnage

1 ton of cooling = 12,000 BTU/h ≈ 3.517 kW
Residential AC units are typically sold in 0.5-ton increments (1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0 tons)
A typical bedroom (150 sq ft / 14 m²) needs about 0.5–1.0 ton
A typical living room (300 sq ft / 28 m²) needs about 1.0–1.5 tons
Central AC systems for whole homes range from 2.0 to 5.0 tons

FAQ

What tonnage do I need for a 1,000 sq ft home?

A 1,000 sq ft home typically needs a 1.5 to 2.0 ton central AC, depending on climate, insulation, and layout. Open-plan homes may need slightly more. Use this calculator for a room-by-room estimate.

Should I round up or down when choosing AC tonnage?

Always round up to the nearest 0.5 ton. If your calculation gives 1.3 tons, choose a 1.5-ton unit. Slightly more capacity is better than undersizing, but avoid oversizing by more than 15%.

Does ceiling height affect AC tonnage?

Yes. Higher ceilings mean more air volume to cool. Standard calculations assume 2.8m (9 ft) ceilings. For rooms with 3.5m+ ceilings, add 15–25% to the calculated tonnage.

📖 Read the Design Guide

AC Size Calculator