The Science Behind BBQ: What is a Good BTU for a Gas Grill?

Jim Bob

Jim Bob

A long-time contributor to GrillBabyGrill. Jim has had a lifelong relationship with the art of grilling, passed on from his father and grandfather to him.

The Science Behind BBQ: What is a Good BTU for a Gas Grill?

Deciding between gas and charcoal is often the biggest decision when buying a grill. While opinions are divided, gas devices are very popular because of their ease of use, low maintenance requirements, and minimal running costs.  

Modern gas grills often come with a host of add-ons, such as side burners and smoke boxes. Although you should consider these options when choosing a grill, another critical factor is the number of BTUs the grill can produce. 

BTUs demonstrate the heat generation capabilities of a burner at its maximum output. However, a high BTU doesn’t indicate the best grill. There are some other things to think about.

1. What Are BTUs?


Photo Courtesy: Appliances Connection

BTU stands for British Thermal Unit. It is a unit of heat and used to express the amount of heat necessary to raise the temperature of 1 lb. of water by 1°F. One BTU is the equivalent of 1,055J (joules), the modern SI unit for heat and energy. So, what relevance does BTU have in terms of a grill?

Most propane-based appliances are rated by BTUs or their energy output capacity. Gas grills are generally measured by their BTU, indicating how much heat they can generate when the burners are set to their maximum outputs

In gas grills, the BTU is measured by overall output and per individual burner. While these figures are important, they are essentially useless if you don’t know the grill’s cooking surface’s size. In most cases, the surface area is more important than maximum heating capacity. 

For example, if you use a small burner with a high BTU to cook food on a large cooking pan, the food near the center of the pan cooks quickly, while the food near the outside cooks much slower. Rather than focusing solely on overall BTUs, grill buyers should prioritize BTUs per square inch.

2. How Many BTUs Do You Need?

In homeware and hardware stores all over the world, BTUs are leveraged by salespeople to upsell. If you ask, “What is a good BTU for a gas grill?” the common answer insinuates that the bigger the BTU, the better. This is problematic for a few key reasons. 

The number of BTUs should be comparable with the size of the cooking surface. If the burners on the grill can’t disperse heat effectively to the cooking area, the BTUs on the appliance are being oversold. 

Additionally, the higher the number of BTUs a burner has, the faster it burns fuel. After estimating your fuel consumption, If you don’t require a high number of BTUs for your usual grilling habits, there is no need to have such a powerful unit.

Grill manufacturers often market their products as having a higher number of BTUs than they actually have. They include the BTU of side-burners in their advertisements, which have no effect on the primary cooking surface. 

For general use, the number of BTUs needed for a grill is somewhere between 75 and 100 BTUs per in2 of cooking surface. If a grill has an output lower than 75 BTUs, it may be very slow to cook. If the output is above 100 BTUs, it may char your food without cooking it through.

While a standard BTU output may be suitable for a 5-person family of barbecue enthusiasts, it may not be enough for a commercial kitchen. Measure the size of your desired cooking space, then calculate how much BTUs you need to provide adequate heat output for it. 

Besides finding the right BTU output, several other considerations have a major influence on cooking quality.

3. How Important Are BTUs In Grilling?

In determining what is a good BTU for a gas grill, the quality of the materials within the appliance is a huge factor. The number of BTUs becomes less relevant if the grill doesn’t have adequate quality for effective cooking. 

The grate, lid, and connections must be of a high enough standard to effectively regulate temperature and withstand the heat output. Heavy construction is desirable, with a tightly fitting lid to capture and retain the heat. There is no need for additional BTUs to compensate for heat loss or a poorly made cooking surface with a high-quality grill. 

The type of material the grill is made from has an effect as well. Varying materials utilize the burner-generated BTUs differently. For example, aluminum heats very quickly but also loses heat fast. The lack of heat retention can make temperature regulation difficult, which could cause increased fuel use and poorly cooked food. 

A cast iron grill takes much longer to heat up, but it retains heat for a long time. This means it absorbs the heat from the BTUs and uses it consistently. Once cast iron grills get hot enough, they cook thoroughly and efficiently, making better use of the heat output. 

When purchasing a new gas grill, ensure that the drip pan, hood, lid, grates, air vents, and other cooking surfaces are of excellent quality and made from the right materials (e.g., cast iron or porcelain). These are some of the most important parts of an appliance that contribute to how efficiently BTUs are distributed

Avoid making a grill purchase based on BTU alone. Certain grill manufacturers develop products with excessively high BTU ratings to make up for a lack of craftsmanship in the grill itself. This overcompensation through heat will ultimately end in lackluster cooking and may result to grill problems.

Read Also: High Quality Tabletop Gas Grills.

4. Infrared Grills

Infrared grills are different from standard propane grills in that they don’t use an open flame to heat the cooking grates. Instead, they use a conductive infrared element between the grates that emits heat towards the cooking surface

Infrared grills don’t need as many BTUs to deliver the same heat output. They can function effectively at a lower BTU. As a rough guide, they operate well between 60 to 80 BTUs per in2 of the cooking surface.