Calculating the Cost of Firing a Kiln

Kilns have a reputation for requiring costly amounts of electricity, and many hobbyists give this drawback as a rationale for using a communal studio instead of starting their own personal home studio.

However, is it actually true that kilns are too expensive to fire, or is this simply a myth?

As it turns out, owning a kiln may actually be more affordable than you think. In order to help you price your pieces or decide if owning a kiln is cost-effective, we’ve put together a guide that explains what factors affect the cost of firing a kiln, how to calculate exactly what firing will cost you, and how to use a formula when considering different kiln models.

Once you know how to calculate the total cost of kiln ownership, you can be certain you are making an informed decision on a serious investment.

5 Factors Affecting Cost of Firing A Kiln

The overall cost of firing a kiln is not dependent on a single factor; details regarding an artist’s electrical situation as well as their interests and habits are equally important when determining how much money will be spent. Here are five main factors to consider when evaluating the cost of kiln firing:

Cost of Electricity

How much an individual is charged for the use of electricity varies from state to state, and from provider to provider. The cost of energy is measured in cents per kilowatt hour (kW), and though the U.S. average is 12.70 cents per kilowatt, the price typically ranges from just over 9 to almost 22 cents per kilowatt (if you live in Hawaii, you could be facing over 30 cents per kilowatt).

The U.S. Energy Information Administration website breaks down the monthly average costs by both region and state, so if you’d like to know how your regional environment affects the cost of kiln firing, you can access the EIA’s database here.

How Much Power Your Kiln Uses

A kiln’s power consumption is largely dependent on its size and design. Smaller kilns that operate on a 120-volt standard household outlet will typically draw between 1.5 and 1.8 kilowatts whereas a medium-sized kiln will draw around 5 kW or 8 kW. Some large kilns can even be as rated as 11kW, so be sure to check the energy requirements on a kiln when considering potential firing costs.

Duration of a Single Firing

Some firing programs take longer than others - firing time can be less than an hour or up to 20 hours - so consider what kinds of projects you’ll be doing. How many steps are involved in each firing program you’ll be running? Are there many annealing periods or ramp/hold cycles, and how long will each take? The longer your firing programs are, the more energy is used, therefore increasing the price exponentially.

Frequency of Firings

How often your kiln is used also affects the cost of running it. Consider if you plan to fire every day, periodically, or only on occasion. If you are firing throughout the day more than once a week, this will increase your cost significantly.

Pieces Fired

The characteristics of the artwork you are firing are also important to note, as they affect the frequency and duration the kiln will be running. Quantity, size, and composition are all important factors to consider; for instance, the more pieces you fire, the more frequently you’ll be firing, and using materials or techniques that require slower or longer firing programs will increase your firing time as well.

Similarly, since big pieces consume more space in a kiln, artists who regularly work on larger projects are more likely to need a larger, higher-energy consuming kiln, or fire more frequently in a medium-sized kiln.

The Cost-Calculating Formula

In order to calculate the cost of a given firing program for a specific kiln, you will need four specific figures. Here’s how to determine each one:

1. First, you will need to establish the cost of electricity in your studio location, as dictated by your provider. Locate your most recent electricity or utility bill, and look for an indication of how much your provider charges per kilowatt hour. As mentioned above, this rate will likely be between $0.09 and $0.22.

2. Next, determine how many kilowatts your kiln uses. If you already have a kiln, locate the electrical data plate attached to the side of the control box to find the volt, phase, amp, and watt capacities of the kiln. If you are still in the research stage, find the watt capacity listed in the product description of the kiln online. Once you know the wattage, convert this number to kilowatts by simply dividing by 1000; for example, 18,000 watts is 18 kW.

3. Now figure out how many hours your firing program will take. Again, if you are calculating the cost of a kiln you already own, digital controllers will display the time elapsed at the end of a firing cycle. If using a manual controller, simply measure the time from when you start the kiln to when you turn it off. If you are still considering different kiln models, you can follow this same procedure by measuring your expected firing cycle of choice from start time to end time.

4. Finally, establish your kiln’s duty cycle. A kiln’s elements are not engaged for the full duration of firing; electricity passes through the elements only when the relays are on, a phenomenon that can be detected by the clicking or humming sound heard when the kiln is operating. A duty cycle refers to the period of time in which a kiln’s elements are actively drawing electricity, and is given in a percentage form (a 100% duty cycle would imply the elements were powered during the entire firing procedure). For a firing program that contains controlled ramp rates, hold times, and other temperature manipulations, the duty cycle is typically 50-60%, meaning a 6-hour program would consist of relays actively drawing power for about 3-4 hours. A low or bisque firing generally has a 50% duty cycle, a glaze firing might be closer to 65%, and preheating only has a 15% duty cycle. It is also important to note that as a kiln ages, its efficiency goes down and therefore its duty cycle goes up.

Once you have deduced these numbers, input your data into the following formula:

(Cost per kilowatt hour) x (kilowatt rating of the kiln) x (program duration) x (duty cycle of the kiln)

=

cost of firing program

Examples of How to Calculate Total Kiln Firing Cost

Once you have the information regarding your electrical costs, your kiln’s energy requirements, and your firing program of choice, you can apply the above formula to a kiln you already have or any kiln you may be interested in purchasing. As a demonstration of how the formula works, here is the cost breakdown of two popular kilns sold at Soul Ceramics:

Example 1: Jen-Ken AF3P 11/9 Electric Glass Kiln

• Cost per kilowatt hour: $0.15. In this scenario, we will assume an electricity charge of medium range, commonly found in many households across the U.S.

• Kilowatt rating: 1.5 kW. The Jen-Ken AF3P 11/49 is a small kiln operating on standard 120-volt household power, so it is rated at 1560 watts.

• Program duration: 2 hours. This is a short total firing time for a smaller project with a basic firing program.

• Duty cycle: 0.6. For this scenario, a 60% duty cycle is assumed, meaning the number you’ll insert into the formula is 0.60.

Calculation:

($0.15 cost/kW-hr) x (1.5 kW rating) x (2 hr duration) x (0.6 duty cycle)

=

$0.27 cost of firing program

Example 2: Evenheat Porcelain/China Kiln - High Fire 2318

• Cost per kilowatt hour: $0.12. This scenario assumes the near average electricity price charged by providers in the U.S.

• Kilowatt rating: 7.4 kW. The Evenheat Porcelain 2318 is a large, high-fire kiln and operates on 240 volts, meaning its energy requirements are higher than what typical household power can accommodate, which is why it is rated dramatically higher than the Jen-Ken AF3P 11/9 at 7400 watts.

• Program duration: 8 hours. This is also a significant increase from our last example, due to the longer firing time needed to fire larger, more complex projects and high-temperature materials.

• Duty cycle: 0.6. As in the first example, this scenario will assume a 60% duty cycle.

Calculation:

($0.12 cost/kW-hr) x (7.4 kW rating) x (8 hr duration) x (0.6 duty cycle)

=

$4.26 cost of firing program

Besides manually calculating costs, you may find your kiln has a digital controller capable of calculating the cost of each firing cycle. Models with this technology require the owner to simply enter the kilowatt per hour cost of their electricity, and will then display the cost at the end of the firing program.

Now that you’re able to more accurately estimate the cost of firing various kilns and programs, you might be surprised to find that firing glass and ceramic projects is more affordable than you expected. If you have any questions or concerns regarding kiln firing costs, please don’t hesitate to contact us!

Additional resources on kilns and pottery

• What to consider when buying an olympic kiln
• Frequently asked questions about kilns
• A guide to kiln temperature ranges