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There is no single best Mr. Heater Buddy for every job. For a genuinely small space, compare the compact Little Buddy MH4B; for portable heat with a low or high setting, the Portable Buddy MH9BX is the middle-ground option; for more output and two 1-pound cylinders, consider the Big Buddy MH18B; and for a higher-output, accessory-oriented design, compare the Buddy FLEX MH11BFLEX. Choose only after checking the intended location, local rules, heat demand, fuel setup, and exact model version.
Compare the current Buddy models
The figures below are specifications and coverage estimates published by Mr. Heater, not independent test results or guaranteed performance. Actual heating needs vary with ceiling height, insulation, layout, and conditions.
| Model | Published output | Manufacturer-stated coverage | Fuel and runtime | Notable features |
|---|---|---|---|---|
| Little Buddy MH4B | 3,800 BTU/h; the product page also labels input as 4,000 BTU/h | Up to 95 sq ft | One disposable 1-pound propane cylinder; runtime not stated on the product page | Compact base, one-button ignition, ODS and tip-over shutoff |
| Portable Buddy MH9BX | 4,000 or 9,000 BTU/h | Up to 225 sq ft | One 1-pound cylinder; optional hose and filter for a 20-pound cylinder. Listed runtime: 3 hours at maximum and 6 hours at minimum output. | Hi/low controls, swivel regulator, fold-down handle, Piezo igniter |
| Big Buddy MH18B | 4,000, 9,000, or 18,000 BTU/h | Up to 450 sq ft | Two 1-pound cylinders; optional hose connection to a 20-pound cylinder. Runtime not stated on the product page. | Hi/medium/low controls, two swivel regulators, ODS and tip-over shutoff. Some currently listed versions omit the fan; verify the exact version. |
| Buddy FLEX MH11BFLEX | 8,000–11,000 BTU/h | Up to 275 sq ft | One 1-pound cylinder; listed runtime is 2 hours at maximum and 3.5 hours at minimum output. | Omni-directional mesh burner, electronic ignition, accessory controls and proprietary rail/quick-connect accessory system |
Which model fits which kind of job?
- Choose the Little Buddy as a candidate when compact size and a small stated coverage area matter more than adjustable output or a larger-cylinder option.
- Compare the Portable Buddy when you want two heat settings and the option to use a manufacturer-compatible 20-pound-cylinder setup.
- Consider the Big Buddy when its higher output range and two-cylinder arrangement suit the space; check whether the exact version includes a fan rather than assuming it does.
- Look at the Buddy FLEX if its burner design and proprietary accessory system match your intended setup. Its coverage estimate is not larger than the Big Buddy’s despite its different features.
Estimate how much heat you need
Mr. Heater gives square footage multiplied by 40 as a generally accepted starting estimate for required BTUs. Treat that as a rough planning aid, not a sizing guarantee: the manufacturer also says ceiling height, building layout, and insulation affect demand. Its published “up to” coverage figures are likewise guidance, not a promise that a heater will maintain a particular temperature in every building or climate. Mr. Heater’s general product information explains the sizing factors.
Start with the area and conditions, then compare the estimate with the model’s output settings. A high-output model is not automatically the better choice for a small or restricted space; the setting, location, and permitted use all matter.
#1 Best Overall
- Emits 4,000 or 9,000 BTU/hr radiant heat
- Designed and approved for indoor and outdoor use
- Heats up to approximately 225 square feet
- Features emergency low oxygen safety system
- 2 temperature settings: low and high
Check the location and local rules before choosing
Whether an unvented propane heater is permitted depends on the jurisdiction, building, and exact model or version. Mr. Heater says rules vary by country, state, and locality. Its published guidance says Massachusetts and Canada do not allow indoor use of propane heaters and describes restrictions on Buddy use in California dwellings; official listings also distinguish some outdoor-use versions. These are manufacturer statements, not a substitute for checking current local codes and the applicable product manual. Review the manufacturer’s location guidance and confirm the rule that applies where you plan to use the heater.
The cited Buddy product pages list an oxygen depletion sensor (ODS) and tip-over shutdown. Mr. Heater describes the ODS as sensing nearby oxygen and shutting off the unit below a set level; its support information describes tip-over shutdown when the heater is tilted past a specified point. These safeguards do not establish that indoor or enclosed-space use is legal or suitable, and they do not replace ventilation, clearance, or operating instructions in the exact model’s owner’s manual. Use Mr. Heater’s support page to locate model documentation.
Rank #2
- 4,000 or 9,000 BTU radiant heat for customizable comfort
- Designed and approved for indoor and outdoor use. Indoor use not approved in Canada or Massachusetts.
- Heats spaces up to 225 sq. ft. with efficient radiant warmth
- Up to 5.4 hours of runtime on a 1 lb. propane tank
- Up to 108 hours of runtime when connected to a 20 lb. propane cylinder with an optional Buddy hose and fuel filter
Plan the cylinder and accessory setup
A 1-pound cylinder keeps the setup portable but means less fuel on hand than a larger-cylinder arrangement. The Portable Buddy page describes an optional hose and filter for a 20-pound cylinder; the Big Buddy connects to two 1-pound cylinders and can use an optional hose to a 20-pound cylinder. Little Buddy’s page lists no hose or regulator included. The manufacturer lists runtime for the Portable Buddy and Buddy FLEX at specific heat settings, but fuel consumption and runtime depend on the selected setting and setup.
Do not assume a generic hose or filter will work. Mr. Heater warns that some hoses can shed oily contaminants into a heater under high-pressure propane flow and identifies F273699 as a fuel filter; it also says certain hose models do not need a filter. Match the exact hose, filter, cylinder configuration, and heater using the manufacturer’s compatibility information. The product pages warn that unauthorized accessories or attachments may cause serious injury and void the warranty. Verify compatibility in the current manual before connecting anything.
Rank #3
- Heats up to 450 square feet
- Low, Medium, and High heat settings: 4,000 / 9,000 / 18,000 BTU
- Heats up to 216 hrs. on two 20lb Propane tanks with optional hose (low setting)
- Big Buddy dual heating system combines radiant heat comfort with convection heat air flow
- Built-in high powered fan
Use and maintain the heater according to its manual
Mr. Heater’s indexed safety-manual title warns: “NEVER LEAVE THE HEATER UNATTENDED WHILE BURNING!” The official safety material also warns against cooking or warming food on the heater. Follow the current manual for the precise model and version, including its instructions on location, clearances, ventilation, fuel connection, ignition, shutdown, and storage.
Quick Recap
Best Value
- Emits 4,000, 9,000 or 18,000 BTU/hr radiant heat
- Designed and approved for indoor and outdoor use
- Heats up to approximately 450 square feet
- 3 temperature settings: low, medium, and high
- The use of un-authorized accessories/attachments with this heater are expressly prohibited, may cause serious injury, and will void the warranty.
Rank #4
- HEAT OUTPUT: Adjustable 6,000, 12,000, or 18,000 BTU settings provide radiant warmth for spaces up to 450 sq. ft.
- SAFETY FEATURES: Equipped with oxygen depletion sensor and automatic tip-over shut-off for worry-free operation.
- FUEL & RUNTIME: Runs up to 72 hours on low with a standard 20 lb tank.
- IGNITION SYSTEM: Push-and-turn piezo ignition offers quick, reliable starts without electricity.
- DESIGN & PORTABILITY: Durable steel cabinet with smooth-rolling casters for easy mobility and outdoor versatility.
A practical selection checklist
- Identify the place of use. Check whether local rules and the building’s requirements permit this type of unvented propane heater there.
- Estimate the heat demand. Use Mr. Heater’s square-footage-times-40 guidance only as a starting point, and account for ceiling height, insulation, and layout.
- Match output and stated area. Compare the settings and manufacturer coverage estimate; do not select by square footage alone.
- Choose a fuel arrangement. Decide whether 1-pound cylinders suit the required portability and runtime, or whether a model-compatible larger-cylinder setup is appropriate.
- Verify the exact product. Check the model/version, current owner’s manual, included equipment, fan status where relevant, and accessory compatibility before purchase.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
