How many BTUs do I need to heat 400 square feet?

APPROXIMATE BTU OUTPUT NEEDED BY SQUARE FOOTAGE

APPROXIMATE SQUARE FOOTAGE	Up to 200	Up to 400
RECOMMENDED INSULATION	4,000 BTU	8,000 BTU
MODERATE INSULATION	6,000 BTU	12,000 BTU
POOR INSULATION	9,000 BTU	18,000 BTU

What size heater do I need for 400 square feet?

As a rule of thumb, you’ll need roughly 10 watts of heating power for every square foot of floor area in the room….Space Heater Sizing Chart.

Calculating Square Footage & Wattage for Heating
Square Footage of Your Space	Wattage
300 sq. ft.	3,000 watts
350 sq. ft.	3,500 watts
400 sq. ft.	4,000 watts

How do I calculate BTU for heating?

For example, a 300 square foot room typically requires 7,000 BTUs to maintain a comfortable temperature, while a 1,000 square foot room requires 18,000 BTUs. A simple formula to determine your heating needs is: (desired temperature change) x (cubic feet of space) x . 133 = BTUs needed per hour.

How many BTU air conditioner do you need for a 400 square foot room?

Air Conditioner BTU Chart; With 12,000 BTU (1 Ton) Room Size Example

Cooling Capacity (BTU):	Room/Area Size:
4,000 BTU air conditioner room size:	100-200 sq ft
6,000 BTU air conditioner room size:	200-300 sq ft
8,000 BTU air conditioner room size:	300-400 sq ft
10,000 BTU air conditioner room size:	400-500 sq ft