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Patio Heater BTU Calculator

Enter the area you want warm and choose gas or electric. The result is the range of heater input implied by the coverage figures manufacturers publish, and every model behind it is listed below.

Inputs

Measure only the area you want warm, not the whole yard.

Gas covers natural gas and propane infrared heaters. Electric covers electric infrared heaters.

This changes the notes under the result. The numbers stay the same.

Result

Heater input for your area

28,000 to 53,300 Btu/h

Lowest published coverage rate
140.0 Btu/h per sq ft (Schwank supremeSchwank 2300 Series, 35K)
Highest published coverage rate
266.7 Btu/h per sq ft (Schwank phantomSchwank STP Series, 80K)
Heater models counted
10 gas models from 2 manufacturers (Bromic, Schwank)

Notes on This Result

  • Cold or windy sites can need more heat than the average coverage figures assume. Schwank says its heaters may cover less than the average area in extremely cold or windy conditions, and does not publish a number for how much less.
  • Wind also cuts a gas heater's performance. Bromic's manual says its Tungsten gas heater is designed for winds up to 10 mph. Its product page says 8 mph. We cite the manual.
  • A fixed gas heater needs a gas supply sized for its input. Check your line with the gas line sizing tool before you buy.

Calculation Details

Formula

Range = your area × the lowest and highest output per square foot found in manufacturers' published heated areas for that heater type.

Assumptions

  • There is no standard for how much heat an outdoor space needs. This range comes from the heated area each manufacturer publishes for its own heaters, divided into the heater's rated input.
  • Manufacturers measure coverage differently and at different mounting heights, which is why the range is wide. The low end is the most generous coverage claim we found. The high end is the most conservative.
  • Sheltered spaces need less than the figures suggest and cold, windy ones need more, by the manufacturers' own notes. None of them publishes a number for how much.
  • Patio heaters warm people, not air. A well-designed installation feels about 3 to 7 degrees warmer at 60°F, by testing Infratech cites. Do not expect a covered patio to feel like indoors.
  • Gas fire pits and fire tables are not rated for heating an area, so this does not size one.

Sources

  1. Bromic, Product Cut Sheet Tungsten Gas (PDF dated 2026-01-22), Specifications table, Heat Area, footnote 'In ideal conditions'; rated input from the Tungsten Smart-Heat Gas product page option list (https://www.bromic.com/product/tungsten-smart-heat-gas/)

    Checked . View at bromic.com.

  2. Bromic, Platinum Smart-Heat Gas product page specification table (Heat Area, Output) and Product Cut Sheet Platinum Gas (https://pim.bromic.com/wp-content/uploads/2026/02/Product-Cut-Sheet-Platinum-Gas-1.pdf)

    Checked . View at bromic.com.

  3. Schwank, Compare Schwank Patio Heater Models (manufacturer page), Coverage Area row; coverage stated at a mounting height of 10 ft

    Checked . View at schwankgroup.com.

  4. Infratech, Choosing your Infratech system chart (IN999_gettingstarted_chart, PDF dated 2025-01-28), Heat Coverage Area and Mounting Height rows

    Checked . View at infratech.com.

  5. Infratech, FAQs, 'How much heat should I expect?': a good patio heat installation provides 3 to 7 degrees of perceived heat at 60 F ambient; more than 7 is too warm to sit in for extended periods. Infratech attributes this to Pacific Gas & Electric's Food Service Technology Center

    Checked . View at infratech.com.

  6. Bromic, Tungsten Smart-Heat Gas Instruction Manual, Version 2.3 USA / Canadian, Installation Requirements, PDF p. 6: the heater is designed to function in winds up to 10 mph

    Checked . View at pim.bromic.com.

  7. Bromic, Tungsten Smart-Heat Gas product page: wind resistance of up to 8 mph

    Checked . View at bromic.com.

Heater Models Behind the Range

Each row is one heater model and the heated area its manufacturer publishes for it. The range in the result runs from the lowest to the highest input per square foot in these tables. Find the heater you are considering to see where it sits.

Gas patio heaters, rated input in Btu/h

Electric patio heaters, rated input in watts

  • Infratech C-15 / W-15Source: Infratech C-15 / W-15

    Rated input
    1,500 W
    Heated area
    25 sq ft
    Input per sq ft
    60.0
    Basis for the coverage
    5 ft x 5 ft; Infratech chart pairs this coverage with a 6 to 7 ft mounting height

  • Infratech SL-16Sets the high end of the rangeSource: Infratech SL-16

    Rated input
    1,600 W
    Heated area
    25 sq ft
    Input per sq ft
    64.0
    Basis for the coverage
    Same coverage group as the C-15 in the chart

  • Infratech C-20 / W-20Source: Infratech C-20 / W-20

    Rated input
    2,000 W
    Heated area
    36 sq ft
    Input per sq ft
    55.6
    Basis for the coverage
    6 ft x 6 ft; Infratech chart pairs this coverage with a 7 to 8 ft mounting height

  • Infratech C-26 / W-26Source: Infratech C-26 / W-26

    Rated input
    2,600 W
    Heated area
    56 sq ft
    Input per sq ft
    46.4
    Basis for the coverage
    7 ft x 8 ft; Infratech chart pairs this coverage with a 7 to 8 ft mounting height

  • Infratech CD-30 / WD-30Source: Infratech CD-30 / WD-30

    Rated input
    3,000 W
    Heated area
    49 sq ft
    Input per sq ft
    61.2
    Basis for the coverage
    7 ft x 7 ft; Infratech chart pairs this coverage with a 7 to 8 ft mounting height

  • Infratech SL-24Source: Infratech SL-24

    Rated input
    2,400 W
    Heated area
    49 sq ft
    Input per sq ft
    49.0
    Basis for the coverage
    Same coverage group as the CD-30 in the chart

  • Infratech C-30 / SL-30 / W-30Source: Infratech C-30 / SL-30 / W-30

    Rated input
    3,000 W
    Heated area
    64 sq ft
    Input per sq ft
    46.9
    Basis for the coverage
    8 ft x 8 ft; Infratech chart pairs this coverage with a 7 to 9 ft mounting height

  • Infratech C-40 / SL-40 / W-40Source: Infratech C-40 / SL-40 / W-40

    Rated input
    4,000 W
    Heated area
    100 sq ft
    Input per sq ft
    40.0
    Basis for the coverage
    10 ft x 10 ft; Infratech chart pairs this coverage with an 8 to 10 ft mounting height

  • Infratech CD-40 / WD-40Source: Infratech CD-40 / WD-40

    Rated input
    4,000 W
    Heated area
    80 sq ft
    Input per sq ft
    50.0
    Basis for the coverage
    8 ft x 10 ft; Infratech chart pairs this coverage with an 8 to 10 ft mounting height

  • Infratech CD-52 / WD-52Source: Infratech CD-52 / WD-52

    Rated input
    5,200 W
    Heated area
    100 sq ft
    Input per sq ft
    52.0
    Basis for the coverage
    10 ft x 10 ft; Infratech chart pairs this coverage with an 8 to 10 ft mounting height

  • Infratech CD-60 / WD-60Source: Infratech CD-60 / WD-60

    Rated input
    6,000 W
    Heated area
    121 sq ft
    Input per sq ft
    49.6
    Basis for the coverage
    11 ft x 11 ft; Infratech chart pairs this coverage with an 8 to 12 ft mounting height

  • Bromic Tungsten Smart-Heat Electric 2000WSource: Bromic Tungsten Smart-Heat Electric 2000W

    Rated input
    2,000 W
    Heated area
    65 sq ft
    Input per sq ft
    30.8
    Basis for the coverage
    Cut sheet heat area

  • Bromic Tungsten Smart-Heat Electric 3000WSource: Bromic Tungsten Smart-Heat Electric 3000W

    Rated input
    3,000 W
    Heated area
    100 sq ft
    Input per sq ft
    30.0
    Basis for the coverage
    Cut sheet heat area

  • Bromic Tungsten Smart-Heat Electric 4000WSource: Bromic Tungsten Smart-Heat Electric 4000W

    Rated input
    4,000 W
    Heated area
    130 sq ft
    Input per sq ft
    30.8
    Basis for the coverage
    Cut sheet heat area

  • Bromic Tungsten Smart-Heat Electric 6000WSource: Bromic Tungsten Smart-Heat Electric 6000W

    Rated input
    6,000 W
    Heated area
    160 sq ft
    Input per sq ft
    37.5
    Basis for the coverage
    Cut sheet heat area

  • Bromic Eclipse Smart-Heat ElectricSource: Bromic Eclipse Smart-Heat Electric

    Rated input
    2,900 W
    Heated area
    121 sq ft
    Input per sq ft
    24.0
    Basis for the coverage
    Cut sheet heat area

  • Schwank eSchwank Ghost ESM, 4kWSource: Schwank eSchwank Ghost ESM, 4kW

    Rated input
    4,000 W
    Heated area
    160 sq ft
    Input per sq ft
    25.0
    Basis for the coverage
    Schwank states coverage at a 10 ft mounting height

  • Schwank eSchwank Ghost ESM, 6kWSource: Schwank eSchwank Ghost ESM, 6kW

    Rated input
    6,000 W
    Heated area
    200 sq ft
    Input per sq ft
    30.0
    Basis for the coverage
    Schwank states coverage at a 10 ft mounting height

  • Schwank eSchwank Electric ES/ESD, 2kWSets the low end of the rangeSource: Schwank eSchwank Electric ES/ESD, 2kW

    Rated input
    2,000 W
    Heated area
    100 sq ft
    Input per sq ft
    20.0
    Basis for the coverage
    Schwank states coverage at a 10 ft mounting height

  • Schwank eSchwank Electric ES/ESD, 4kWSource: Schwank eSchwank Electric ES/ESD, 4kW

    Rated input
    4,000 W
    Heated area
    140 sq ft
    Input per sq ft
    28.6
    Basis for the coverage
    Schwank states coverage at a 10 ft mounting height

  • Schwank eSchwank Electric ES/ESD, 6kWSource: Schwank eSchwank Electric ES/ESD, 6kW

    Rated input
    6,000 W
    Heated area
    160 sq ft
    Input per sq ft
    37.5
    Basis for the coverage
    Schwank states coverage at a 10 ft mounting height

What the Result Means

The result is a range of heater input, not a recommendation. The low end comes from the most generous coverage claim we found and the high end from the most conservative one, which is why the two ends sit far apart. Find the heater you are considering in the tables below the calculator. A heater near the low end is counting on its manufacturer's best-case coverage. A heater near the high end is making the cautious claim.

Mounting height changes the coverage. Infratech and Schwank both tie each coverage figure to a mounting height, and a heater mounted higher covers more area less intensely. Wind and cold reduce it: both say their heaters can cover less than average in extremely cold or windy conditions, and neither says by how much. Bromic's manual says its Tungsten gas heater is designed for winds up to 10 mph. Shelter works the other way, and well-protected spaces generally get more than the average coverage.

Plan to warm people, not the air. Infratech cites testing that puts a good installation at 3 to 7 degrees of perceived heat at 60°F, and says more than 7 is too warm to sit in for long. Even a covered patio will not feel like indoors.

This calculator does not size a fire pit or a fire table, because they are not rated for heating an area.

Call a licensed installer or electrician in three cases. Bromic limits gas heaters to open-air situations and sets minimum open wall areas for covered, walled spaces, so a patio near that line needs a site visit. A fixed gas heater needs a gas supply sized for its input, which is licensed work. Start with the gas line sizing calculator. Electric heaters of 4 kW and up run on 208 to 277 V circuits, so have an electrician size the circuit. Infratech and Bromic both offer layout design for a specific patio.

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