Most mobile homes need 10,000 to 20,000 watts of electric heating capacity, but the right number comes from a load calculation, not square footage alone.
Manufactured housing loses heat faster than a stick-built house of the same size, and that gap decides what wattage you can actually get away with. The wattage question has a real answer, but it sits behind four variables: square footage, insulation, air leakage, and how cold your winter gets. Get those four right and the number falls into place. Skip them and you’ll either shiver through January or trip a breaker every cold snap.
How Many Watts Does A Mobile Home Need To Heat?
Plan on 10,000 to 20,000 watts for whole-home electric heat, which works out to roughly 35,000 to 70,000 BTU at peak winter load. That range is wide on purpose. A tight, well-insulated double-wide in a mild climate sits near the bottom. An older single-wide with single-pane windows and leaky skirting pushes the top.
The quick estimating rule for manufactured homes is 25 to 30 BTU per heated square foot. Multiply your square footage by 30, convert BTU to watts by dividing by 3.41, and you have a starting figure. A 1,200-square-foot home lands around 36,000 BTU, or about 10,500 watts, before you adjust for anything.
That’s the floor, not the answer. Two homes with identical floor plans can need very different wattage once you factor in how much air leaks out of them.
What Changes The Wattage You Actually Need?
Insulation quality, window type, air leakage, ceiling height, and your local winter design temperature are the five levers that move the number most. A home with poor skirting and unsealed belly board can need 30 to 50 percent more capacity than a well-sealed neighbor of the same size.
Electric heat strips are sold by kilowatt rating, and the BTU output maps cleanly:
| Heat Strip Size | BTU Output | Typical Home Size |
|---|---|---|
| 5 kW | 17,000 BTU | Small rooms, additions |
| 7 kW | 24,000 BTU | Small single-wide, mild climate |
| 8 kW | 27,000 BTU | 1,000 sq ft, moderate insulation |
| 10 kW | 34,000 BTU | 1,200 sq ft, average build |
| 12 kW | 41,000 BTU | 1,400 sq ft, mobile home furnace only |
| 15 kW | 51,000 BTU | 1,600 sq ft, cold climate |
| 17 kW | 58,000 BTU | 1,800 sq ft, mobile home furnace only |
| 20 kW | 68,000 BTU | 2,000 sq ft, harsh winters |
Two of those sizes matter more than the rest if you’re shopping a manufactured-home furnace: 12 kW and 17 kW are offered only with mobile home electric furnaces. Standard electric furnaces don’t come in those ratings.
What Safety And Equipment Rules Apply?
The U.S. Consumer Product Safety Commission states that mobile homes require specially designed heating equipment, and that only electric or vented fuel-fired units should be installed. An unvented gas heater in a manufactured home is not an option.
More detail sits in the CPSC’s portable heater safety guidance.
One more gate catches a lot of older homes: the electrical service itself. A 20 kW heat package pulls roughly 83 amps at 240 volts, which can overwhelm a 100-amp panel that’s already carrying a range and a dryer. Check the panel rating and available circuit capacity before you buy anything.
How Do You Size It Correctly?
Run a Manual J-style load calculation if you can get one. It’s the most reliable method and it accounts for every variable at once. If that isn’t practical, work through these in order:
- Measure the heated square footage, excluding unheated porches and additions.
- Note insulation levels in walls, ceiling, and floor, plus the age and glazing of your windows.
- Walk the home on a windy day and feel for drafts at outlets, doors, and skirting.
- Look up your local winter design temperature, not your average January low.
- Confirm the electrical service can carry the kilowatt package you picked.
The most common sizing mistake is choosing wattage from square footage alone. Insulation, climate, and air leakage together outweigh floor area in most mobile homes. The second most common mistake is installing equipment that wasn’t built for manufactured housing, which voids warranties and can fail inspection. If you’re comparing specific units before you commit, our tested picks for mobile home electric heaters walk through which models fit which panel sizes.
FAQs
Is 10,000 watts enough to heat a mobile home?
It depends on size and climate. A 1,200-square-foot home with decent insulation in a moderate climate can run on 10,000 watts, which produces about 34,000 BTU. An older, leakier home in a cold region will fall short and need 15,000 watts or more.
Can I run a space heater in a mobile home?
Never use an unvented fuel-burning heater in a manufactured home.
Why can’t I just size by square footage?
Square footage ignores the three variables that drive heat loss hardest: insulation quality, air leakage, and winter design temperature. A tight home and a drafty home of identical size can need 30 to 50 percent different wattage.
References & Sources
- U.S. Consumer Product Safety Commission. “Portable Heater Safety.” Supports the 3-foot clearance, extension cord, and cord-under-rug rules.
- U.S. Consumer Product Safety Commission. “Heater Safety.” Covers designed-for-manufactured-housing requirements and fueling rules.
- U.S. Consumer Product Safety Commission. “CPSC Warns Consumers to be Cautious When Using Space Heaters, Furnaces and Fireplaces This Winter.” Supports the oversized-heater hazard warning.