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I believe the Mr Heater Buddy is one of the best indoor, portable propane heaters for emergency preparedness. I have a Mr Heater “Big Buddy” and a “Portable Buddy”, and I can attest to their performance. One common question is about the Buddy Heater’s run time — how long will it run on a 1-lb or 20-lb propane tank, on both low and high settings?
In this guide, you’ll find Mr. Heater Buddy and Big Buddy run-time charts, comparisons for 1-lb vs 20-lb propane tanks, and real-world tips to make your fuel last longer.
Contents (Jump to a Section)
Understanding the Buddy Heater Lineup
Note: The “Little Buddy” (model MH4B, runtime ~5-6 hrs) is a smaller 3,800 BTU version — unlike the Portable Buddy (MH9BX) and the Big Buddy (MH18B).
The primary difference between the Mr. Heater Portable Buddy and the Portable Big Buddy is that the Big Buddy has two catalytic heater elements. More BTUs. This is illustrated in the image below. Note that they are both portable.
The Big Buddy provides double the maximum heating power and can warm larger areas, making it better suited for bigger spaces or colder conditions.
The Big Buddy consumes more fuel at higher settings due to its greater output and dual-cylinder design. Still, it offers flexibility with two cylinders for longer runtime at lower settings. The Buddy is more fuel-efficient for smaller spaces.
Mr. Heater Big Buddy 18,000 BTU = model MH18B
Mr. Heater Buddy 9,000 BTU = model MH9BX
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Best Overall: Big Buddy 18,000 BTU Indoor-Safe Heater
Longest runtime and dual-tank option.
Best Budget: Buddy 9,000 BTU Indoor-Safe Heater
Most popular.
Now that you know which Buddy model fits your needs, here’s approximately how long each will run on 1-lb and 20-lb propane tanks.
Buddy Heater Run-Time Chart (Mr. Heater Buddy 1-lb & 20-lb Tanks)
On average, a Buddy Heater runs about 5 to 6 hours on a 1-lb tank and around 90 hours on a 20-lb tank, depending on heat setting and conditions.
Quick Tip: The Big Buddy 18,000 BTU Heater on Amazon delivers double the heating capacity and longer run times when connected to a 20-lb propane tank.
| Model | BTU Range | Tank Type | Run Time (Low) | Run Time (Med) | Run Time (High) |
|---|---|---|---|---|---|
| Buddy | 4,000–9,000 | 1-lb | 5.4 hrs | — | 2.4 hrs |
| Buddy | 4,000–9,000 | 20-lb | 92 hrs | — | 41 hrs |
| Big Buddy | 4,000–18,000 | (Two) 1-lb | 10.8 hrs | 4.8 hrs | 2.4 hrs |
| Big Buddy | 4,000–18,000 | 20-lb | 92 hrs | 41 hrs | 20 hrs |
Summary: A Buddy Heater runs about 5–6 hours on a 1-lb tank and roughly 90 hours on a 20-lb tank; the Big Buddy doubles those times with dual cylinders.
These numbers are approximate and based on my experiences and extrapolations from specifications. Your times may vary. However, this should provide a good idea for those who are interested. Typically, manufacturer specs are based on ideal conditions, which you may or may not encounter.
Run times will be significantly reduced when operating below ~ 20 °F and at higher altitudes.
According to the manufacturer’s specifications for the Big Buddy (MH18B), when connected to two 1-lb. disposable propane cylinders, run-time is approximately 3 to 12 hours, depending on the heat setting and conditions. Since the manufacturer doesn’t provide fixed hours for each setting, our table uses calculated estimates (assuming ~17 lb of fuel equivalent) for the low, medium, and high outputs.
20-lb tank figures are estimated based on full tank weight and BTU rating.
Let us know in the comments about your own run-time experiences with 1-lb cylinders and 20-lb BBQ grill tanks.
Also read: How To Tell How Full (or Empty) Your Propane Tank Really Is
Big Buddy Official Owner’s Manual
Big Buddy Manual (PDF) – Page 4
“Operating Time: Single 1-lb cylinder 1.5–6 hrs | Two 1-lb cylinders 3–12 hrs | 20-lb cylinder 24–108 hrs | Two 20-lb cylinders 48–216 hrs.”
Portable Buddy Manual (PDF) – Page 4
“Operating time ≈ 3–6 hrs (1 lb) and 48–110 hrs (20 lb) depending on setting.”
How Long Will a Buddy Heater Run on Low?
The Buddy model on low (4,000 BTU) runs about 5.4 hours per 1-lb cylinder or 92 hours on a 20-lb tank.
The Big Buddy on low (4,000 BTU dual burners) gives about 10.8 hours on two 1-lb tanks. If you’re searching ‘how long will a Big Buddy heater run on a 20 lb tank,’ here’s the data… roughly 92 hours on a 20-lb tank.
Mr Heater Buddy (4,000 – 9,000 BTU)
The 9,000 BTU model features a standard design that accepts a 1-lb disposable propane bottle.
See reference below for 20-pound tank adapter.
MH9BX Portable Buddy Heater Run Time
1-lb bottle: 5.4 hours on low
1-lb bottle: 2.4 hours on high
20 lb tank: about 92 hours on low
20 lb tank: about 41 hours on high
20 pound propane tank run times based on typical ‘full’ fill level of 4 gallons, and propane weighing 4.25 pounds per gallon (17 pounds of propane).
Mr Heater Big Buddy (4,000 – 9,000 – 18,000 BTU)
The 18,000 BTU model will accept two 1-lb propane bottles.
See reference above for 20-pound tank adapter.
MH18B Big Buddy Heater Run Time
(2) 1-lb bottles: 10.8 hours on low
(2) 1-lb bottles: 4.8 hours on med
(2) 1-lb bottles: 2.4 hours on high
20 lb tank: about 92 hours on low
20 lb tank: about 41 hours on med
20-lb tank: about 20 hours on high
| Model | Pros | Cons | Best For | Amazon Link |
|---|---|---|---|---|
| Buddy (9,000 BTU) |
Compact, fuel-efficient (92 hrs low on 20 lb), affordable. | Single burner; smaller area (225 sq ft). | Tents, small rooms. | [Check Price] |
| Big Buddy (18,000 BTU) |
Dual burners for faster heat (450 sq ft), longer on two 1 lbs (up to 12 hrs). | Heavier, higher fuel use on high (20 hrs on 20 lb). | Garages, cabins. | [Check Price] |
How to Hook Up a 20-lb Propane Tank to Your Buddy Heater
To connect your Buddy or Big Buddy Heater to a 20-lb propane tank, you’ll need a compatible Mr. Heater adapter hose.
In addition to 1 lb propane bottles, the heater can also connect to a barbecue-style 20-pound propane tank for a long-lasting fuel source.
You might consider using the following adapter hose with a larger tank, since 1-lb propane bottles are much more expensive (though convenient for quick portability!).
Hose Attachments for 20-lb propane tank:
Check current price and reviews on Amazon
This fits both the Buddy (9,000 BTU model) and Big Buddy (18,000 BTU),
>> F273704 (Screw-on Buddy Hose)
This fits only the Big Buddy (18,000 BTU model),
>> F271803 (Quick-Connect Buddy Hose w/Regulator)
Will the F273704 work on both the Buddy Heater and Big Buddy Heater?
Yes, the F273704 is fully compatible with both the standard Portable Buddy (MH9BX) and Big Buddy (MH18B/MH18BX) heaters. It connects directly to the standard 1 lb cylinder screw-on port present on both models, allowing safe use with 5-20 lb tanks without a filter.
Does the F271803 only work with the Big Buddy Heater?
Essentially, yes. It is designed specifically for the Big Buddy (MH18B/MH18BX) and Tough Buddy heaters, connecting via their dedicated 3/8″ quick-connect port (located next to the 1 lb cylinder port). The standard Portable Buddy lacks this quick-connect port, so the F271803 cannot connect directly to it without adapters (which Mr. Heater does not officially recommend). It can also hook into low-pressure RV propane lines, making it versatile for those setups.
Why does the F271803 have a regulator while the F273704 does not?
The Mr. Heater F271803 includes a regulator because it connects to the Big Buddy heater’s dedicated 3/8″ quick-connect port, which bypasses the heater’s built-in regulator. This port is designed for pre-regulated, low-pressure propane input (typically 1/2 PSI, or around 11-14 inches water column), such as from an RV’s low-pressure propane system or a bulk tank with a regulator. Without an integrated regulator, high-pressure propane (up to 200 PSI from a 5-20 lb tank) would flow directly into the heater, risking damage or unsafe operation. The F271803’s regulator reduces tank pressure to the safe, low level required by the quick-connect port.
The F273704, however, lacks a regulator because it connects to the standard 1 lb cylinder port on both Portable Buddy and Big Buddy heaters. This port feeds into the heater’s built-in regulator, which is designed to handle both high-pressure input from a bulk tank (via the hose) and low-pressure input from a 1 lb cylinder. The heater’s internal regulator adjusts the pressure appropriately (to ~0.5 PSI), so an external regulator in the hose would be redundant and could disrupt the heater’s performance by over-regulating the flow.
UPDATE: You can also refill your own 1lb cylinders with the following adapter:
1-lb propane bottle refill adapter
If you do use a 20 pound (BBQ) tank, it is recommended to keep that tank outdoors. You might snake the hose through a window. Stuff a towel in the crack (to keep cold air from getting in) as you close the window on the hose.
Propane-Saving Tips During Power Outages
Here are a few propane-saving tips for Buddy Heater users during power outages…
- Heat the room to the comfort level, then turn the heater off
- Use thermal curtains or blankets
- Keep window shades and curtains closed
- Seal drafts
- Layer clothing for extended fuel life
- Store extra propane safely outdoors
Typically, you will not leave this heater on all the time. So the propane fuel consumption numbers listed here may actually last longer.
The use case may be to heat the room (area) and then shut off the heater until needed again. Saves lots of fuel this way. The better the insulation in your home, the longer it will take to cool down again.
During an emergency, you are better off rationing your fuel and staying in a cooler home while wearing layers of warm clothes—rather than blowing through your fuel in a T-shirt…
Indoor Safety Tips for Buddy Heaters
It is listed as safe to use indoors, but use common sense!
- Carbon monoxide detector
- Tip-over shutoff and oxygen sensor
- Ventilation awareness
- When operating the heater at altitudes above 7,000 ft, it may shut off. (low oxygen shutoff)
It is a very efficient catalytic-type heater. Although it’s essentially 100% efficient, I strongly advise installing a carbon monoxide detector.
Also, sleeping in space heated by any type of fuel combustion is always potentially risky. I would not sleep without a CO detector nearby.
This is the CO detector that I use:
Carbon Monoxide Alarm with Battery Backup
(view on Amazon)
[ Read about: Carbon Monoxide Poisoning ]
Buddy Heater FAQ
Approximately 5 to 6 hours on a 1-lb propane tank, or around 90 hours on a 20-lb tank — actual runtime varies with temperature and altitude.
Estimated runtimes are about 92 hours on low, 41 hours on medium, and 20 hours on high. Actual performance can vary slightly depending on conditions.
It’s possible, but not recommended, without proper ventilation and a working carbon-monoxide detector. Run time estimates assume intermittent daytime use.
Mainly BTU output and fuel setup — the Big Buddy (MH18B) uses dual burners and supports two 1-lb or 20-lb tanks, while the Buddy (MH9BX) is smaller (single 4,000 BTU burner).
Typically, 2 to 5 hours, depending on the heat setting and model. These figures are approximate, based on manufacturer specs and real-world testing.
Note: Run times are approximate and depend on temperature, altitude, and propane fill level.
Buddy Heater and Emergency Preparedness
For the cold winter season, evaluate your emergency backup heat sources. Run through the scenario of a power outage. Especially one that might last longer than just a few hours!
One product that I discovered (and purchased) is the ‘Mr Heater Buddy’ (pictured above). I have found them to be reasonably practical (and portable) for winter preparedness, emergency situations, and peace of mind!
It’s a portable propane heater and is indoor-safe. You might use it for emergency home heating. Or portable use in a cabin, garage, workshop, trailer, RV, greenhouse, porches, patios, hunting blinds, etc..
Regardless of whether you heat with oil, natural gas, LP, or electricity, there is likely a component in the heating system that requires 120-volt electrical power to operate. Susceptible to power outage.
Examples include a blower fan, pumps (oil pump, water circulation pumps), electronic igniter, thermostats, etc.. When the power goes out, so will your furnace.
The Power Might Be Out Longer Than You Think
Common power outage scenarios include severe winter weather. Heavy snow. Wind. Ice storms. Trees and limbs come down – and power goes out.
A power outage during a winter storm (especially an ice storm) will often last longer than you might expect due to poor weather conditions and the time it takes to get crews out to begin repairs (clearing snow and ice, cutting trees and limbs, repairing lines, etc.).
The sheer number of repairs may take the power company a long time to catch up!
Be ready, be prepared.
Whether you’re heating a garage, cabin, or prepping for winter outages, the Mr. Heater Buddy series remains one of the most efficient indoor-safe propane heaters available.
👉 Check today’s prices and bundle options on Amazon before cold weather hits.
NEW: I love this Heater Buddy carry bag cover for portability. It will fit two extra 1-pound cylinder propane tanks, the hose, and other accessories.
Portable Carry Bag
(Amazon)
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17 Comments
Considering the Buddy Heater’s performance and the factors that affect its run time, it seems like a reliable option for emergency heating needs, especially when paired with a 20-lb propane tank for extended use.
The run-time chart provided shows that a Buddy Heater runs about 5 to 6 hours on a 1-lb tank and around 90 hours on a 20-lb tank, depending on heat setting and conditions, which seems like a significant difference in efficiency.
I appreciate the distinction made between the different Buddy models, such as the Little Buddy being a smaller 3,800 BTU version, and how each is suited for different needs and spaces, which helps in making an informed decision.
The mention of the Big Buddy being better suited for bigger spaces or colder conditions due to its higher BTU output and dual-cylinder design makes it a strong candidate for those who need reliable heating in more demanding environments.
It’s good to know that the Big Buddy has a dual-tank option for longer runtime at lower settings, which could be beneficial for extended use in emergency situations or in larger spaces that require more heating power.
I’m curious about the difference in fuel efficiency between the Mr. Heater Portable Buddy and the Big Buddy, especially considering the Big Buddy has two catalytic heater elements and consumes more fuel at higher settings.
The Big Buddy’s dual-cylinder design does offer flexibility with two cylinders for longer runtime at lower settings, which could be a significant advantage in certain situations.
The fact that the Buddy Heater’s run time can vary significantly based on the heat setting and conditions means it’s crucial to plan accordingly and possibly have backup fuel sources, especially in critical emergency preparedness situations.
The comparison of run times on 1-lb versus 20-lb propane tanks provides valuable insight into the efficiency and potential cost-effectiveness of using larger tanks for extended heating needs, especially with the Big Buddy model.
I’m interested in learning more about how the catalytic heater elements in the Big Buddy contribute to its increased heating capacity and efficiency, and whether this technology is used in other heating solutions.
The discussion on the fuel efficiency and run times of the Buddy Heaters highlights the importance of choosing the right model and tank size for specific needs, whether it’s for smaller, more enclosed spaces or larger areas that require more heating power.
I’ve been using the Mr. Heater Buddy for emergency preparedness and can attest to its performance, especially in smaller spaces where it’s more fuel-efficient, but I’m interested in learning more about its limitations in colder conditions below 20 °F.
The tip about the Big Buddy 18,000 BTU Heater delivering double the heating capacity and longer run times when connected to a 20-lb propane tank is useful for those looking to maximize their heating power and efficiency.
The comparison between the Little Buddy, Portable Buddy, and Big Buddy models is helpful in understanding their respective strengths and weaknesses, particularly how the Big Buddy provides double the maximum heating power and can warm larger areas.
Understanding the impact of external conditions, such as temperature below 20 °F, on the Buddy Heater’s performance is crucial for planning and ensuring that heating needs are met during emergencies or in harsh weather conditions.
I’m skeptical about the manufacturer specs being based on ideal conditions and how that might impact real-world performance, especially since run times will be significantly reduced when operating in colder temperatures or at higher settings.
The image illustrating the difference between the Mr. Heater Portable Buddy and the Portable Big Buddy was helpful in visualizing their designs and understanding why the Big Buddy offers more heating power and flexibility.