Mr. Heater Buddy vs Big Buddy vs Little Buddy vs Buddy FLEX: Specs Compared
Every Buddy heater side by side from Mr. Heater's spec tables - and which size fits your space
Mr. Heater's Buddy series all use the same approach: radiant propane heat, an oxygen depletion sensor, and a tip-over shutoff, and Mr. Heater lists them as indoor-safe. The models differ in output, area, fuel setup, and weight.
Buddy Heaters Side by Side (per Mr. Heater)
| Spec | Little Buddy | Portable Buddy | Buddy FLEX | Big Buddy |
|---|---|---|---|---|
| Model | MH4B | MH9BX | Buddy FLEX | MH18B |
| BTU settings | 3,800 | 4,000 / 9,000 | Up to 11,000 | 4,000 / 9,000 / 18,000 |
| Heats up to | 95 sq ft | 225 sq ft | 275 sq ft | 450 sq ft |
| Fuel | One 1 lb cylinder | One 1 lb, or 20 lb with hose and filter | One 1 lb cylinder | Two 1 lb, or 20 lb with hose |
| Run time | 5.6 hr | 3 hr high / 6 hr low | 2 hr high / 3.5 hr low | Up to 11 hr (two 1 lb) |
| Weight | 5.85 lb | 10.6 lb | 11.02 lb | 17.1 lb |
The Amazon listing for the Portable Buddy gives shorter run times (2.4 hr high, 5.4 hr low) than Mr. Heater's spec table. The Big Buddy PRO listing adds a built-in fan.
Buddy vs Big Buddy: How to Choose
Space: match the maker's square-footage rating to your room, then allow for insulation and cold. Fuel: both can run from a 20 lb grill tank with Mr. Heater's hose (the Portable Buddy page also calls for a filter); for long sessions, that beats swapping 1 lb cylinders. Carrying: at 10.6 pounds, the Portable Buddy is the easier one to move around; the Big Buddy is 17.1 pounds.
Big Buddy vs Big Buddy PRO
On Amazon you'll see two 18,000 BTU Big Buddy listings. The Big Buddy PRO listing describes the same three settings (4,000, 9,000 and 18,000 BTU) and the same 450-square-foot rating, plus a built-in fan that it says combines radiant heat with convection airflow. That listing was unavailable when we rechecked on October 12, 2026.
The standard Big Buddy (MH18B) we link above has the same settings and rating and is listed as radiant heat. Mr. Heater's own MH18B page notes that it "has removed the fan on some models," so if a fan matters to you, check the listing before you buy. Both use the oxygen depletion sensor and tip-over shutoff, and Mr. Heater rates the Big Buddy for up to 11 hours on two 1 lb cylinders.
The short answer: the fan helps spread heat around a larger garage, but it doesn't change the BTU or square-footage rating. If the PRO isn't available, the standard Big Buddy does the same heating job.
Common Questions
Is the Big Buddy twice as warm as the Buddy?
Its top setting is 18,000 BTU vs 9,000 on the Portable Buddy, and Mr. Heater rates it for 450 vs 225 square feet. Both also have 4,000 and 9,000 BTU settings.
Can I use either one in a garage?
Mr. Heater lists both as indoor-safe and lists garages among their uses. Keep a CO alarm running and follow the ventilation instructions. For a garage you heat every day, see our garage heater guide.
Bottom Line
The Portable Buddy for rooms, tents, and single work areas up to 225 square feet; the Big Buddy for spaces up to 450. See our propane heater guide for the full lineup, or kerosene vs propane if you're weighing fuels. For no-propane heat in an outage, see our kerosene heater guide.
Where to Buy Our Picks
The products from this guide, with current prices on Amazon.
Most Spaces
Mr. Heater Portable Buddy (MH9BX)
4,000/9,000 BTU, up to 225 sq ft, 10.6 lb, one 1 lb cylinder or 20 lb with hose and filter, per Mr. Heater.
Check price on AmazonSold by Amazon
Larger Spaces
Mr. Heater Big Buddy (MH18B)
- 4,000/9,000/18,000 BTU
- Up to 450 sq ft
- 17.1 lb
- Two 1 lb cylinders or 20 lb with hose
Sold by Northern Tool + Equipment on Amazon
Smallest
Mr. Heater Little Buddy (MH4B)
- 3,800 BTU
- Up to 95 sq ft
- 5.85 lb
- One 1 lb cylinder
Sold by Amazon
Mid-Size
Mr. Heater Buddy FLEX
11,000 BTU max, up to 275 sq ft, about 2 hr high / 3.5 hr low on a 1 lb cylinder, 11.02 lb, per Mr. Heater.
Check price on AmazonSold by Amazon
Sources
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