Skip to main content
Fan Size Calculator Heater Size Calculator Plastic Size Calculator Surface Area Calculators
Not sure what size heater you need for your greenhouse kit? Our Greenhouse heater size calculator does all the work for you. Just enter in all of the greenhouse information below. Then you can choose from our extensive selection of greenhouse heaters and thermostat controls.
Greenhouse Heater Size Calculator
Surface Area of Greenhouse - This is the total square feet of exposed surface area (this is not length x width) your greenhouse has (don't include floor). To find out the surface area of a greenhouse we sell, click here. To find the surface area of a different greenhouse, click here to use our greenhouse area calculators.
Minimum Outside Temperature (°F) - You will want to enter the lowest temperature expected for your area. Not sure? Use the USDA Zone Map to find the minimum temperature for your area.
Inside Temperature (°F) - This is the minimum temperature you would want to maintain in your greenhouse when heating.
Heat Loss Value - Check the list below to find the heat loss value for the covering on your greenhouse. Some values may vary with manufacturer. If you know the R-value of your covering, you can convert it to a heat loss value using this formula: Heat loss value = 1 / R-value.
Area x (In - Out) x Heat Loss
Minimum BTUs Needed - This is the minimum amount of BTU output your greenhouse heater should have. If the heater only has a BTU input rating, use the following formula. BTU output = heater efficiency * BTU input. View Our Selection of Greenhouse Heaters

Greenhouse Covering Heat Loss Values
4 mil polyethylene
1.20
4 mm (5/32") twinwall polycarbonate
.70
6 mil polyethylene
1.15
6 mm (1/4") twinwall polycarbonate
.62
6 mil poly double layer (inflated)
.70
6mm polycarbonate roof & glass walls
.90
11 mil woven polyethylene
1.05
8 mm (5/16") twinwall polycarbonate
.58
3 mm (1/8") glass (single layer)
1.13
10mm (3/8") twinwall polycarbonate
.53
Double layer insulated glass
.45
10 mm (3/8") triple wall polycarbonate
.48
Polycarbonate / fiberglass (single layer)
1.20
16 mm (5/8") 5 wall polycarbonate
.33

Greenhouse Exposed Surface Area
Grow More Greenhouses
GM8 (8' x 11') 333 GM8ext (8' x 5') 104
GM10 (10' x 13') 442 GM10ext (10' x 6.5') 149
GM13 (13' x 13) 557 GM13ext (13' x 6.5') 175
GM16 (16' x 13') 681 GM16ext (16' x 6.5') 202
Sunshine Greenhouses
GKP64 - 6' x 4' 195 GKP88 - 8' x 8' 369
GKP68 - 6' x 8' 273 GKP812 - 8' x 12' 462
GKP612 - 6' x 12' 352 GKP816 - 8' x 16' 555
Cross Country Greenhouses
Because of the large number of sizes available, you will need to use our surface area calculator
to find the total surface area for the model you are interested in.
Sterling GG45 Gas Heater sterling, gg, gg45, gas, heater, furnace, garage, greenhouse, shop, unit, beacon, morris, cheap, sale, free, GG045A1NSA11, GG045A1PSA11, GG045A2NSA11, GG045A2PSA11
Free Shipping
Price: $825.00

Sterling GG gas heaters are an excellent option for heating garages, greenhouses, sheds, etc. Each Sterling GG heater includes: tubular heat exchanger, electronic ignition, power exhaust system, advanced diagnostic system for dependable worry-free operation, lots of safety features, high power fan to provide even heat distribution, rust-resistant aluminized steel exchanger, and a baked-on enamel finish made to protect them from harsh environments. Designed for propane or natural gas. Some...

King Pic-A-Watt 240v Electric Heater king, 240, 220, volt, electric, heater, greenhouse, space, garage, shop, small, portable, fan, room
Price: $659.00

Need help sizing a heater for your greenhouse? Use our Greenhouse Heater Size Calculator This rugged heater will provide your greenhouse, garage, or shop with years of reliable heating. The King heater has an amazing 19,454 BTU output at the 5700 watt setting. Everything about this heater is high quality including the accurate capillary thermostat (Range 40° F to 85° F), sealed and permanently lubricated fan motor, delayed fan which continues to run after heater cuts off to remove heat from...

Bio Green 120v Stainless Steel Waterproof Heater bio, green, palma, greenhouse, heater, waterproof, 120, volt, stainless, steel, water, line, voltage
Sale!
Price: $129.00

Need help sizing a heater for your greenhouse? Use our Greenhouse Heater Size Calculator The Bio Green Palma portable heater is made specifically for wet environments like greenhouses! It features a stainless steel housing, totally enclosed fan motor, and is completely waterproof (IPX4 rated). Another feature unique to this heater is that the fan runs continuously in heat mode providing optimal air circulation and heat distribution. Measures: 12.5"H x 10"W x 8"D. Requires 110/120 volt outlet....

Williams DV14 Direct Vent Gas Heaters  williams, direct, vent, gas, heater, furnace, wall, mount, dv, vented, greenhouse, sealed, 1403822, 1403821, 4100105, 4100100
Free Shipping
Price: $897.00

Sealed Combustion & No Electricity Required!Williams direct vent wall heater draws outside air to the sealed combustion chamber and vents exhaust gases directly outside. This feature is highly recommended if you grow orchids. No electricity required, so heater will continue to operate normally even during an electrical power outage. Great heating option for greenhouses, garages, rooms in homes, and work shops.Williams Direct-Vent heaters are designed for quiet operation. Convenient, Piezo...

Contact Us

Contact Us

ACF Greenhouses
380 Greenhouse Drive
Buffalo Junction, Virginia 24529
1-888-888-9050 toll free

We Accept