Cast Iron Skillet Size Chart: Number, Rim Diameter, Cooking Surface and Weight
The number cast into a vintage pan is a wood-range stove-eye size, not an inch measurement, and the inch figure on a modern pan is the outside rim diameter. Both overstate the flat floor you cook on by roughly 1.7 to 2.4 inches, and a machined vintage No. 8 gives you more usable surface at a pound less weight than a modern 10.25-inch pan of the same nominal class.
By the Cast Iron FAQ Editorial Team
A No. 8 is not eight inches. It measures about 10.5 inches across the rim, and the flat floor you actually cook on is closer to 8.8. The number is a leftover from wood-burning ranges, where it referred to the diameter of the stove eye the pan was meant to drop into, and it stopped meaning anything the moment kitchens went to flat hobs.
The modern number is more honest but still misleading. A pan sold as 10.25 inches is 10.25 inches across the outside of the rim at the top. Sand-cast walls flare outward, so by the time you reach the floor you have lost between 2.0 and 2.4 inches of diameter, which is roughly 40% of the area. Vintage machined pans have straighter walls and give back about half an inch of that.
Chart first, then the arguments.
The chart
Ranges rather than single figures, because the same number was cast by at least six foundries with different patterns. A Griswold No. 8 and a Wagner No. 8 are not the same object, and neither is a Birmingham Stove & Range No. 8. Modern masses are for current production sand-cast pans; vintage masses are for machined pre-1960 domestic skillets in sound condition.
Size Rim dia (in) Flat floor — machined vintage (in) Flat floor — sand-cast modern (in) Depth (in) Mass, vintage (lb) Mass, modern (lb) Burner match Best use IronGrade — / 3.5 in (modern mini) 3.4-3.6 no period equivalent 2.4-2.6 0.8-1.0 — 1.0-1.2 Smallest burner, or oven only One egg, a single side, toasting a tablespoon of whole spice 34 No. 3 / 6.5 in 6.4-6.6 4.9-5.2 4.5-4.8 1.2-1.4 1.6-1.9 2.2-2.6 4-6 in One egg with room to turn it, a single small chop 58 No. 4 / 7 in 6.8-7.1 5.2-5.6 4.9-5.2 1.3-1.5 1.9-2.3 2.5-2.9 5-6 in Two eggs, one pork chop, garlic bread for one 62 No. 5 / 8 in 7.9-8.2 6.2-6.6 5.8-6.2 1.4-1.6 2.6-3.0 3.6-4.1 6 in Two eggs, one 6 oz fillet, a small frittata 71 No. 6 / 9 in 8.9-9.2 7.0-7.4 6.6-7.0 1.5-1.7 3.1-3.6 4.2-4.8 6-7 in One steak, three eggs, a 6 in cornbread 78 No. 7 / 10.25 in 10.1-10.4 8.2-8.7 7.6-8.1 1.7-1.9 3.6-4.1 5.1-5.6 7-8 in One large steak, four eggs, standard cornbread, a skillet cookie 92 No. 8 / 10.5-10.75 in 10.5-10.9 8.6-9.1 8.0-8.5 1.8-2.0 4.0-4.6 5.5-6.1 8 in One ribeye with room around it, a shallow braise for two 95 No. 9 / 11.5 in 11.4-11.8 9.4-9.9 8.8-9.3 1.9-2.1 4.9-5.6 6.4-7.1 8-9 in Two chops, eight chicken thighs skin-down, a deep-dish base 84 No. 10 / 12 in 11.9-12.3 9.8-10.3 9.2-9.7 2.0-2.2 5.5-6.3 7.8-8.4 9 in Two steaks side by side, a family sear, 10 in cornbread 88 No. 11 / 12.75 in 12.6-13.0 10.4-10.9 9.8-10.3 2.0-2.2 6.4-7.2 8.6-9.4 9-10 in Four-serving sear, a whole spatchcocked bird under a weight 70 No. 12 / 13.25 in 13.1-13.5 10.9-11.5 10.2-10.8 2.1-2.4 7.4-8.5 9.8-10.7 10-11 in Six servings, big-batch hash, two spatchcocked birds at a push 74 No. 13 / 14 in 13.9-14.3 11.6-12.2 10.9-11.5 2.2-2.5 8.6-9.8 11.4-12.5 11 in or a two-burner bridge Eight servings; realistically an oven and grill pan more than a hob pan 55 No. 14 / 15.25 in 15.0-15.4 12.6-13.3 11.8-12.6 2.4-2.7 10.4-12.1 12.6-13.6 12 in, two burners, or coals Catering volume, campfire cooking, oven-only for most domestic hobs 48 Read across from the size you own or are considering, and judge it on the flat-floor column rather than the rim. If you are buying, the two rows scoring above 90 are the sizes that earn a permanent hook. Notice what happens between the two mass columns. A vintage No. 8 at 4.0 to 4.6 lb gives you a slightly larger flat floor than a modern 10.25 in pan weighing 5.1 to 5.6 lb. That is not a rounding error — it is a pound and a half of iron doing nothing for you, and it is the single clearest physical difference between the eras.
Numbers above No. 12 and below No. 5 are collector territory more than kitchen territory. The small ones are charming and rarely used; the big ones are magnificent and rarely liftable one-handed once loaded.
Why the number has nothing to do with inches
Wood and coal ranges had removable cast lids over each opening, and the openings came in graded sizes. A pan numbered 8 was built to sit in the No. 8 eye with its base down in the firebox heat and its rim resting on the stove top. The heat ring on the underside of many pre-1930s skillets exists for exactly that reason — it is a locating feature for a stove eye, not a design flourish.
The sizes were never standardised across foundries the way, say, thread pitches were. Griswold, Wagner, Favorite, Wapak, Birmingham Stove & Range and dozens of smaller works all cast their own patterns to their own dimensions, and a No. 8 from one is commonly 3 to 8 mm off a No. 8 from another. Handle length varies more still.
When gas and electric ranges took over, the eye disappeared and the number stopped describing anything real. Foundries kept casting it because customers kept asking for it, then gradually dropped it. By the 1970s most domestic pans carried inches instead, and a lot carried nothing at all — which is the reason so many inherited skillets arrive at this site with no identifying information whatsoever beyond their geometry.
Rim diameter versus the floor you cook on
This is the measurement that decides whether four eggs sit flat or slide into each other, and no manufacturer prints it. Wall angle is what sets it: the steeper the wall, the more of the rim diameter survives down to the floor.
Pan class Typical wall flare Rim → floor loss (in) Usable share of rim diameter Floor on a 10.5 in rim (in) What that costs or buys you Machined vintage, pre-1960 (Griswold, Wagner, Favorite) 10-15° from vertical 1.6-1.9 83-85% 8.6-9.1 Most surface per pound of pan; the flattest floor of any class Modern boutique machined (Field, Stargazer, Butter Pat) 12-18° 1.7-2.1 80-84% 8.4-8.9 Vintage-class floor with a current warranty behind it Post-1960 domestic sand-cast (Lodge and equivalents) 20-25° 2.0-2.4 77-81% 8.0-8.5 Sloped walls make tossing and basting easier; you lose floor for it Budget import sand-cast 22-28° 2.2-2.6 75-79% 7.8-8.3 Steepest area loss, and the least consistent pan-to-pan Enamelled cast iron skillet 18-25° 2.0-2.5 76-81% 8.0-8.5 Similar geometry to sand-cast, plus a glass layer that rounds the floor-to-wall junction Cast iron grill pan 20-30° 2.2-2.8 73-79% 7.7-8.3 Ridges remove roughly half the remaining contact area again — treat the floor figure as notional Use this to translate any advertised inch figure into the number that matters. Subtract the loss for your pan class from the rim diameter and that is what you are cooking on. There is a practical test that takes ten seconds. Lay a ruler across the inside of the pan and find where the floor stops being flat and the radius starts. That point, doubled from centre, is your real cooking surface. Most owners are surprised by an inch or more.
Weight, and where it turns from a feature to a problem
Thermal mass is the reason anyone cooks on iron in the first place. A heavy pan barely notices a cold steak, which is why the sear holds instead of stalling. That argument is sound right up to the point where you cannot safely move the pan.
The practical ceiling for most people is about 6 lb empty for a pan they need to lift one-handed off a hob with food in it. Add a pound of protein and the leverage of a 7-inch handle and a 6 lb pan is already asking for a real grip. At 8 lb and up — which is where every modern 12 in sits — it becomes a two-hand job with a towel, and everyone who owns one has a story about the moment they discovered that.
This is where era matters most. If a 12 in modern pan is too much and you still want the floor area, a vintage No. 10 gets you within half an inch of the same cooking surface at roughly 6 lb rather than 8. It is the strongest argument for buying old that exists, and it is a physical one rather than a nostalgic one.
Matching a pan to a burner
Overhang is the variable nobody checks. A pan whose base extends more than about 2 inches beyond the flame ring on gas develops a hot centre and a cool rim, and on electric radiant it is worse because the element does not spill heat sideways the way a flame does.
Rule of thumb: pan floor should be within about 2 inches of the burner or element diameter, in either direction. A 6 in burner under a 12 in pan gives you a 6 in hot spot and cool edges, which is exactly the complaint behind most "my cast iron heats unevenly" messages. The pan is fine. The pairing is not.
Two workarounds actually help. Preheat in a 400-450°F oven for 15 minutes and move the pan to the hob, which loads the whole mass evenly rather than through one contact patch. Or rotate a hob-heated pan 90° every couple of minutes during preheat, which costs nothing and evens things out noticeably. Cranking the burner higher does not work; it just deepens the gradient.
If you only own three
A No. 8 or 10.25 in as the everyday pan. It is the size the whole category is built around, it fits an 8 in burner, it holds one steak with room to move it, and it is the last size most people can wield comfortably with one hand when loaded.
A No. 5 or 8 in for eggs and single portions. Small pans get used far more than anyone expects, because the barrier to heating 3 lb of iron for two eggs is a lot lower than heating 6 lb.
A No. 10 or 12 in for anything family-sized. Accept it will live in the oven and on the hob rather than in a cupboard, because you will not want to lift it in and out of storage.
Skip the 13 in and 15 in unless you cook over coals or cater. They are wonderful objects and they spend most of their lives on a wall. Skip the 3.5 in entirely unless you want a serving dish.
Measuring a pan you already have
Four measurements identify almost any skillet well enough to place it in an era class, and all four take a tape measure and a set of digital scales.
Rim diameter goes across the outside of the top edge at the widest point, taken twice at right angles — a difference of more than 2 mm between the two readings means the pan is out of round, which usually means it has been dropped or heated unevenly. Depth is from the inside floor to the top of the rim. Mass is empty, on kitchen scales, in pounds and ounces because that is how every reference table records it.
The fourth is wall thickness at the rim, taken with a caliper across the top edge. Under 3 mm puts a pan in the machined or boutique class. Over 3.5 mm puts it in the modern sand-cast class. That single reading separates the two mass columns in the chart above more reliably than any mark on the underside — which matters, because a great many pans do not carry a mark at all.