The temperature you need to fire clay depends on the type of clay and the stage of firing, but most clay fires between 1,800°F and 2,400°F (1,000°C to 1,300°C). Earthenware fires at the lowest temperatures, stoneware in the middle, and porcelain at the highest. Getting the right temperature matters because too low leaves clay weak and porous, while too high can warp or melt your piece.
Firing Temperatures by Clay Type
Each type of clay has a maturation point, the temperature at which it becomes its strongest and most durable. Firing below that point leaves the clay underdeveloped. Firing above it risks warping, bloating, or collapse.
Earthenware (including terra cotta) matures at the lowest range, topping out around 2,012°F (1,100°C). This is considered low-fire clay. After firing, earthenware stays relatively porous, which means it absorbs water unless you apply a glaze. It keeps rich, warm colors like deep reds and earth tones because of the iron oxides naturally present in the clay. Earthenware is a good starting point for beginners and works well for decorative pieces, tiles, and planters.
Stoneware matures at higher temperatures, reaching up to about 2,372°F (1,300°C). At these temperatures, the clay becomes extremely dense, non-porous, and strong. Stoneware resists thermal shock well and holds up to heavy daily use, which is why most functional pottery (mugs, bowls, dinnerware) is stoneware. Fired stoneware tends to range from gray to brown in color.
Porcelain requires the most heat, maturing at temperatures up to 2,552°F (1,400°C). The result is a white, translucent, glass-like material with virtually zero porosity. Porcelain is harder to work with because it’s less forgiving at every stage, but the finished product is the most refined and durable of all ceramic types.
Bisque Firing vs. Glaze Firing
Most pottery goes through the kiln twice. The first trip is the bisque firing, and the second is the glaze firing. Each serves a different purpose and happens at a different temperature.
Bisque Firing
Bisque firing transforms raw, fragile clay into a hard but still porous state. The porosity is intentional: it allows the piece to absorb glaze evenly in the next step. For stoneware and porcelain, the standard bisque temperature range is cone 08 to cone 04, roughly 1,728°F to 1,945°F (942°C to 1,063°C). Low-fire clays like white earthenware and terra cotta are typically bisque fired a bit higher, at cone 02 to cone 1, around 2,016°F to 2,109°F (1,102°C to 1,154°C).
Raku clay, designed for the rapid heating and cooling of raku firing, is usually bisque fired to cone 04 through cone 1. If you’re planning to use crystalline glazes, bisque a little higher than normal (cone 02 to cone 1) so the clay body is more stable during the demanding glaze firing that follows.
Glaze Firing
The glaze firing is where you bring the clay to its full maturation temperature and melt the glaze coating into a smooth, glass-like surface. This firing is matched to the clay body. Low-fire glazes typically fire around cone 06 to cone 04 (1,828°F to 1,945°F). Mid-range firings land at cone 4 to cone 6 (2,167°F to 2,232°F), which is the most common range for studio potters using electric kilns. High-fire glazes go to cone 8 through cone 10 (2,280°F to 2,345°F) and are more common in gas or wood kilns.
Matching the glaze to the clay body’s firing range is critical. If a glaze is formulated for a different temperature than the clay, the two materials expand and contract at different rates. This mismatch causes crazing (a web of fine cracks in the glaze) or shivering (flakes of glaze popping off the surface). Both are structural defects, not just cosmetic ones. Always check that your glaze and clay are rated for the same cone.
What Cone Numbers Mean
Potters measure kiln temperature using pyrometric cones, not just thermometers. A cone is a small pyramid of ceramic material designed to bend and melt at a specific combination of temperature and time. This matters because clay responds to heat work, not just peak temperature. A kiln that climbs slowly does more heat work than one that reaches the same temperature quickly.
Cone numbers run from low (cone 022, the coolest) to high (cone 13 and above). The most commonly referenced cones for pottery are cone 06 (about 1,828°F) for low-fire work, cone 6 (about 2,232°F) for mid-range, and cone 10 (about 2,345°F) for high-fire. When you buy clay or glaze, the label will list its recommended cone range. Match those numbers and you’re on safe ground.
Critical Temperatures During Firing
Several things happen inside clay at specific temperatures, and understanding them helps you avoid cracked or ruined work.
Between roughly 660°F and 1,100°F (350°C to 600°C), all the chemically bonded water inside the clay burns off. If moisture remains trapped because the kiln heated too quickly, steam pressure can cause pieces to crack or even explode. This is why the early stage of any firing should ramp up slowly, especially for thick-walled pieces.
At 1,063°F (573°C), a transformation called quartz inversion occurs. The silica crystals inside the clay suddenly shift their structure, causing a rapid expansion of about 2%. This happens in both directions: the clay expands at this temperature while heating up and contracts at the same temperature while cooling down. If the kiln moves through this zone too fast in either direction, the stress can crack your work. Slowing down around this point is one of the simplest ways to protect your pieces.
Above 1,800°F (1,000°C), the clay begins to vitrify. Tiny glass-forming minerals melt and fill in the gaps between clay particles, fusing the material into a dense, hard structure. How far this process goes depends on your peak temperature. Low-fire clays only partially vitrify, leaving them porous. High-fire clays vitrify almost completely, producing a waterproof, stone-like body.
Cooling Safely
Cooling is just as important as heating, and rushing it is one of the most common causes of cracked pottery. The technical term for cooling cracks is “dunting,” and it happens most often around that quartz inversion point of 1,063°F. A safe cooling rate through this zone is about 200°F per hour. For larger or thicker pieces, even slower is better.
Most electric kilns cool on their own once you turn them off, and the natural rate is usually fine for small to medium work. For sculpture or anything with uneven wall thickness, programming a controlled cool-down makes a real difference. Resist the urge to crack the kiln lid open early. The temperature inside can still be well above the danger zone even hours after the firing ends.
Low-Fire vs. High-Fire: Choosing Your Range
Your firing temperature shapes the final character of your work in practical ways. Low-fire clay (cone 06 to cone 04) stays porous after firing and offers the widest palette of glaze colors, from bright reds and oranges to vivid blues. It’s forgiving to work with and fires quickly, making it a natural fit for decorative pieces, tiles, and classroom projects. The tradeoff is durability: low-fire ware chips more easily and isn’t ideal for items that need to hold liquid without a well-fitted glaze.
High-fire clay (cone 6 to cone 10) produces pieces that are nearly impermeable to water, highly resistant to chipping, and able to handle thermal shock from things like hot liquids or oven use. The color range in both clay and glaze tends toward more subdued, earthy tones. Whites, grays, and browns dominate because the iron impurities that give low-fire clay its warmth burn out at higher temperatures. If you’re making functional dinnerware, bakeware, or anything meant for heavy daily use, high-fire is the better choice.