BTU: What It Means and How Much You Need
BTU (British Thermal Unit) measures how much heat a propane heater produces per hour.
Tabletop heaters run 8,000 to 11,000 BTU, sized for the people at one table with in a few feet.
Standing heaters run 40,000 to 48,000 BTU, covering a 10 to 15 foot radius in open air, enough for most single-family patios or decks.
Compare heaters with in the same category.
A tabletop heater's lower BTU number isn't a weakness, it's sized for a different job than a standing heater.
Wattage: The Electric Equivalent
Electric infrared heaters use watts instead of BTU, and the two aren't directly convertible into each other.
Most outdoor-rated electric infrared heaters run 1200W to 1500W, producing directional, felt heat similar in principle to sunlight rather than warming the surrounding air the way a propane convection heater does.
Compare electric heaters to each other by wattage and rated coverage area, not by trying to translate wattage into an equivalent BTU number.
Propane vs. Electric
Propane generally delivers more heat per dollar spent and doesn't need an outlet nearby, making it the default for open patios and decks w here local rules allow tank use and storage.
Electric infrared plugs into a standard outlet, can be permanently mounted to free up floor space entirely, and sidesteps any restriction on propane tanks.
It's the practical choice for balconies, covered porches with limited floor space, and anyw here a low-profile mounted install matters more than maximum heat output.
Infrared vs. Convection Heat
Infrared heaters, propane or electric, warm objects and people directly rather than warming the surrounding air.
Convection-style standing propane heaters (the common umbrella-top design) heat the air around them, which then circulates through the space.
Infrared tends to perform more consistently in open or windy outdoor conditions since it isn't relying on warmed air that can simply blow away.
Safety Certifications to Look For
CSA or ETL certification on propane heaters indicates the unit passed independent third-party safety testing, a baseline worth confirming on any listing regardless of price.
Auto-shutoff tilt valve cuts fuel flow if the heater is knocked over, a meaningful feature on any tabletop or standing propane heater.
IP rating on electric heaters indicates weatherproofing.
IP55 or higher is the mark of genuine outdoor durability rather than light water resistance.
Ongoing Costs to Budget For
A 1500W electric heater costs roughly 24 cents per hour at typical U.S.
electricity rates, dropping further on lower heat settings.
Our picks
Products we recommend
As an Amazon Associate I earn from qualifying purchases. Picks are based on manufacturer specs, independent reviews and owner reports.
Best overallSolaira
Ceiling mount uses zero floor space, ideal for a furnished covered porch
- 1500W / 120V quartz infrared element
- 10 by 10 foot coverage area
- Ceiling or wall mount, 4-inch slim housing
- No combustion, no carbon monoxide risk
✓ Pros
- Ceiling mount uses zero floor space, ideal for a furnished covered porch
- No combustion byproducts, so it's genuinely safer in a lower-airflow covered space
- Near-instant quartz warmup means no waiting for the space to feel the effect
✕ Cons
- Requires a dedicated circuit for permanent installation
- Higher price than any propane option on this list
- Coverage is fixed to roughly a 10 by 10 foot zone directly below and in front of it
Top pickAZ Patio Heaters
48,000 BTU and a 10 to 15 foot radius cover most single-heater deck layouts on their own
- 48,000 BTU propane burner
- 87-inch hammered bronze standing design
- 10 to 15 foot heat radius
- Wheeled base, push-button ignition
✓ Pros
- 48,000 BTU and a 10 to 15 foot radius cover most single-heater deck layouts on their own
- The tall standing design puts heat above head height, spreading it evenly over a seating area rather than one hot spot
- Wheeled base makes it realistic to reposition as the party moves around a large deck
✕ Cons
- 87 inches tall and visually bulky, not the pick for a smaller or more curated space
- Needs 3 to 5 feet of clear floor space in every direction
- Burns through a 20lb tank in roughly 8 to 10 hours at full output
Fire Sense
Lower flame height than a full-size standing heater, easier to keep with in overhead clearance limits
- 10,000 BTU propane burner
- Stainless steel tabletop design
- Auto-shutoff tilt valve
- CSA approved
✓ Pros
- Lower flame height than a full-size standing heater, easier to keep with in overhead clearance limits
- Auto-shutoff tilt valve adds a marg in of safety under a roof
- Inexpensive way to add heat to a covered porch that already has good airflow on two sides
✕ Cons
- Still an open flame, unsuitable for a fully enclosed or low-airflow porch regardless of height
- Requires verifying overhead clearance against the manufacturer's spec before using indoors-adjacent
- Smaller heat radius than the electric mounted options
FAQ
Common questions
What does BTU mean for a patio heater?
BTU, British Thermal Unit, measures heat output per hour. A tabletop heater rated 10,000 to 11,000 BTU is sized for the people at one table. A standing heater rated 40,000 to 48,000 BTU covers a 10 to 15 foot radius, enough for most patios or decks. Higher BTU generally means a larger effective heat radius, but wind and cold ambient temperature both reduce real-world performance below the rated number.
How is an electric infrared heater's wattage different from a propane heater's BTU?
They measure different things and aren't directly interchangeable. Watts measure electrical power draw, while BTU measures heat output. A 1500W electric infrared heater produces real, noticeable warmth in a directional path, roughly comparable in felt heat to a mid-size propane heater at close range, but it doesn't cover as wide an area as a 40,000-plus BTU standing propane unit.
What's the difference between infrared and convection patio heaters?
Infrared heaters, whether propane or electric, warm objects and people directly in their path, similar to how sunlight feels warm. Convection-style propane heaters (the common umbrella-top standing design) warm the surrounding air, which then circulates. Infrared tends to work better outdoors in open or windy conditions since it doesn't rely on warming air that can blow away.
What safety certifications should I look for?
CSA (Canadian Standards Association) and ETL (Intertek) are the two most common safety certifications on propane patio heaters sold in North America, both indicating the unit passed independent safety testing. For electric heaters, look for an IP rating, IP55 or higher for genuine outdoor weatherproofing, along with UL listing for the electrical components.
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