Pottery calipers measure the opening or width of a pot and let you carry that size to another piece. Potters use them most to throw a lid that fits its jar, and to make mugs, bowls or plates that match. The best pottery calipers for most people are a lid caliper, which reads the inside of an opening on one end and gives the matching outside size on the other, so you only measure once. Below we compare five calipers using maker pages and US dealer listings. This is a research-based comparison; we did not throw lids with these tools ourselves.
Calipers are an add-on, not a first tool. Our clay tools guide explains where they sit among the basics.
Quick picks
- Best overall: Giffin Grip Lid Master (one measurement gives inside and outside size; 12.5% shrinkage hole)
- Best for big pots: Giffin Grip Large Lid Master (measures pots up to 20 in)
- Best classic metal caliper: Kemper AL aluminum calipers (8, 10 or 12 in; rust-free hardware)
- Best wooden caliper: Kemper CA10 hardwood caliper (10 in; measures thickness and diameters)
- Best budget gauge: Xiem Potter's Clay Gauge (inside, outside and depth, up to 7 in)
Pottery calipers compared
| Caliper | Type | Capacity or length | Material | Shrinkage setting | Typical price band | Buy |
|---|---|---|---|---|---|---|
| Giffin Grip Lid Master | Lid caliper | 0 to 11.5 in (Krueger) | Plastic (Clay-King) | Yes, 12.5% | $16 to $20 | Check price |
| Giffin Grip Large Lid Master | Lid caliper | Up to 20 in (50.8 cm) | Plastic (Clay-King) | Yes, 12.5% | $27 to $30 | Check price |
| Kemper AL8, AL10, AL12 | Standard caliper | About 8, 10 or 12 in long | Aluminum alloy | No | $12 to $18 | Check price |
| Kemper CA10 | Standard caliper | About 10 in long | Hardwood | No | $15 to $18 | Check price |
| Xiem Potter's Clay Gauge | Caliper and depth gauge | Up to 7 in (18 cm) | Plastic | No | $5 to $8 | Check price |
Price bands are what we saw at maker stores and US dealers in October 2026. Several of these calipers showed as sold out on the maker's own store when we checked, so check the live price and stock at more than one dealer.
1. Giffin Grip Lid Master: best overall pottery calipers
The Lid Master comes from Giffin Grip, the company behind the well-known trimming jig. Its trick is the pivot position. A normal caliper measures one size, and you then need a second caliper to transfer it the other way. The Lid Master's arms cross so that when one end fits the inside of an opening, the other end is already set to the matching outside size. Giffin Grip says it "does the work of two calipers" and puts it simply: make one measurement and you have its opposite immediately.
A second hole lets you move the pivot screw to allow for a 12.5% shrinkage factor, which Giffin Grip says shows how much a pot will shrink during firing. Dealers add that this lets you size finished work or make a lid for a pot that has already been fired, without a separate shrinkage ruler. Krueger Pottery lists the standard model as measuring 0 to 11.5 in; Giffin Grip's own page does not give the capacity. Clay-King lists it as plastic.
Giffin Grip's own store showed the Lid Master as sold out in late October 2026, while Krueger and Clay-King still listed it. AMACO also sells a tool called the Lid Master that Nasco says sizes lids up to 11-1/2 in and is made in the USA; neither seller says whether it is the same tool.
- Type: inside/outside lid caliper
- Capacity: 0 to 11.5 in (Krueger); not published by Giffin Grip
- Shrinkage setting: secondary pivot hole for 12.5%
- Material: plastic (Clay-King)
- Typical price band: $16 to $20 (October 2026)
Pros
- One measurement gives both sizes
- Built-in shrinkage setting
- Light and easy to clean
Cons
- Fixed 12.5% ratio may not match your clay
- Capacity not on the maker page
- Out of stock at the maker in October 2026
Who should skip it: potters who do not make lidded pieces yet; a plain caliper is cheaper for matching sets.
2. Giffin Grip Large Lid Master: best for big jars and casseroles
The Large Lid Master works the same way as the standard model, but Giffin Grip says it measures pots up to 20 in (50.8 cm). That covers casseroles, large storage jars, cake domes and wide serving dishes with lids, which are beyond the standard model's roughly 11.5 in reach. It keeps the same 12.5% shrinkage hole.
The bigger arms are the trade-off. They take more space in a tool bag and are less handy on a small sugar bowl or teapot lid than the standard size. If most of your lidded pieces are jars and teapots under 10 in across, the standard Lid Master is easier to use. If you plan a set of large lidded bakers or throw on a 14 in bat regularly, the large model saves you guessing.
Like the standard model, it was shown as sold out on Giffin Grip's store when we checked, with Clay-King, Chesapeake Ceramics and Aardvark Clay still listing it.
- Type: inside/outside lid caliper
- Capacity: up to 20 in (50.8 cm)
- Shrinkage setting: secondary pivot hole for 12.5%
- Material: plastic (Clay-King)
- Typical price band: $27 to $30 (October 2026)
Pros
- Handles very wide lids
- Same one-step reading
- Shrinkage hole
Cons
- Bulky for small lids
- Costs more
- Out of stock at the maker in October 2026
Who should skip it: potters making mugs, small jars and teapots, where the standard Lid Master is enough.
3. Kemper AL aluminum calipers: best classic metal caliper
A standard caliper is two curved arms on a pivot. You set the tips to a width, lock the size by the friction of the pivot, and carry it to the next piece. Kemper makes three aluminum versions, AL8, AL10 and AL12, about 8, 10 and 12 in long. Kemper says they transfer measurements from a model to clay for both inside and outside dimensions, and are made from a tough aluminum alloy with rust-free hardware, which matters for a tool that lives next to water.
This is the tool to buy for matching sets. Set it to the rim of your first mug, then check each mug after it. For lids, a standard caliper works too, but you set it to the gallery, then flip or reset it to measure the lid; that two-step process is what the Lid Master avoids. The 10 in AL10 suits most home work. JB Tools lists it at 45 g.
Kemper's own store showed AL8, AL10 and AL12 with none in stock in late October 2026. Dealers such as Aardvark Clay and JB Tools still listed them. Our Kemper pottery tools review explains the brand's AL codes.
- Sizes: AL8, AL10, AL12 (about 8, 10 and 12 in long)
- Material: aluminum alloy; rust-free hardware
- Use: inside and outside measurements
- Weight: 45 g for AL10 (JB Tools)
- Typical price band: $12 to $18 by size (October 2026)
Pros
- Low price
- Light
- Will not rust
- Three sizes
Cons
- Needs two settings for a lid
- Pivot can loosen and lose the size if knocked
- Out of stock at the maker in October 2026
Who should skip it: potters who mainly want lids to fit and dislike resetting tools; buy the Lid Master instead.
4. Kemper CA10 hardwood caliper: best wooden caliper
Kemper's CA10 is the wooden version: about 10 in long, made from imported hardwood with rust-free hardware that adjusts by hand. Kemper says it transfers measurements from a model to clay and measures thickness and diameters. Wooden arms are thicker than aluminum ones, which some potters find easier to hold and see, and wood will not scratch a leather-hard surface if you rest the tips on it.
The downsides are the usual ones for wood near water: dry it after use and do not leave it soaking, or it can swell or warp. Kemper's store showed the CA10 out of stock in late October 2026, and Aardvark Clay listed it. Our wooden pottery tools guide covers other wood tools and how to care for them.
If you want several sizes in wood, Royal & Langnickel sells a Potter's Select Wooden Caliper Set of three through Blick; a UK dealer lists the sizes as 8, 10 and 12 in. We did not capture a US price for it.
- Length: about 10 in
- Material: imported hardwood; rust-free hardware
- Use: transfer sizes, measure thickness and diameters
- Typical price band: $15 to $18 (October 2026)
Pros
- Thick arms are easy to hold
- Gentle on soft clay
- Measures wall thickness
Cons
- Wood needs drying and can warp
- No shrinkage setting
- Out of stock at the maker in October 2026
Who should skip it: potters who leave tools in a wet bucket; aluminum or plastic copes better with that.
5. Xiem Potter's Clay Gauge: best budget gauge with depth
The Xiem Potter's Clay Gauge is a small, light plastic tool that combines a caliper with a depth gauge. Clay-King says it is for measuring inner, outer and depth measurements on thrown and hand-built work, reads in inches and centimeters, and has a maximum measurement of 7 in (18 cm). It is yellow, so it is easy to find on a cluttered table.
The depth reading is what sets it apart. Matching the height and inside depth of a set of cups or bowls is as important as matching their width, and a standard caliper does not measure depth. Clay-King also suggests it for sizing lids on jars and teapots, within that 7 in limit. At the price, it is an easy add to any order.
Xiem is a US tool brand; see our Xiem pottery tools review for its other lines.
- Measures: inside, outside and depth
- Maximum: 7 in (18 cm); inch and cm scales
- Material: lightweight plastic, yellow
- Typical price band: $5 to $8 (October 2026)
Pros
- Measures depth as well as width
- Low price
- Easy to read and clean
Cons
- 7 in limit
- No shrinkage setting
- Light plastic can flex
Who should skip it: potters making large bowls, casseroles or platters, where 7 in is too short.
Other calipers worth knowing
Richeson sells steel calipers in 8, 10 and 12 in through Blick for inside or outside measuring, and Art Alternatives sells a stainless steel caliper; both are plain calipers like the Kemper AL range. A plastic digital caliper from a hardware store is useful for wall thickness and shrinkage test tiles, but its jaws are too short for most lids. Some potters also 3D print lid calipers; quality varies with the file and printer.
How to choose pottery calipers
Lid caliper or standard caliper
A lid caliper reads both sides of a measurement at once, which is faster and removes the step where most lid errors happen. A standard caliper is simpler and cheaper and better for checking that a set matches. If you only buy one and you make lidded jars or teapots, buy a lid caliper. If you throw sets of mugs and bowls, a standard caliper or the Xiem gauge is enough.
Size and reach
Buy for the widest piece you plan to measure. A caliper around 10 in long, or a standard Lid Master, covers mugs, jars and most bowls. Casseroles and large lidded jars need the Large Lid Master or a 12 in caliper. Small calipers are easier to handle on narrow teapot openings.
Plastic, metal or wood
Plastic is light, cheap and easy to clean, but thin arms can flex. Aluminum and steel hold a setting well and do not mind water if the hardware is rust free. Wood is comfortable and gentle on clay but needs drying. All three work; the choice is about how you handle and store tools.
Shrinkage settings
Clay shrinks as it dries and fires, so a lid thrown to fit a fired pot must be made larger while wet. The Lid Master's second hole uses a fixed 12.5% factor. Shrinkage varies by clay body, so check the figure your clay maker publishes, and see our clay shrinkage guide for how to test it. If your clay shrinks noticeably more or less than 12.5%, treat the setting as a starting point.
Do you need calipers yet?
Most beginners do not, and a ruler works for rough checks. Calipers pay off once you start making lidded forms or sets that have to match, usually after a few months of throwing.
How to measure a lid with calipers
Measure the jar and the lid at the same stage, ideally both while still soft or both at leather hard, so they shrink together. The steps below are the general method; your teacher's way may differ.
- Throw the jar with a gallery, the small ledge inside the rim where the lid sits.
- With a standard caliper, set the tips to the inside of the gallery where the lid will rest. With a Lid Master, put one end inside the gallery and read the matching outside size on the other end.
- Throw the lid, then check its outer edge or flange against the caliper setting while the clay is still soft enough to adjust.
- Leave a small gap rather than a tight fit, so glaze does not lock the lid on.
- Dry the lid on its jar if you can, so both shrink together. If you fire them together, keep glaze off every surface where lid and jar touch.
The same caliper setting lets you throw a run of matching mugs or nesting bowls. Measure the first one you like, then check each one after it at the rim and, with the Xiem gauge, at the depth. Our guide to improving pottery skills has more practice ideas.
Care and safety
Wipe calipers with a damp cloth after use; clay that dries on the arms or pivot flakes off as dust. Dry wood and metal calipers before you put them away, and keep the pivot tight enough that a setting holds. Pack them flat in a tool roll or bag pocket so the tips do not bend; our pottery tool bag guide compares options.
Dry clay dust contains crystalline silica. Measure and trim at leather hard rather than bone dry where you can, wet-clean your table and tools instead of brushing them, and wear a NIOSH-approved respirator when you handle dry clay or glaze materials.
Sources: Giffin Grip Lid Master and Large Lid Master product pages; Krueger Pottery Supply Giffin Tec Lidmaster listing; Clay-King Lid Master small and large listings and Xiem Potter's Clay Gauge listing; Chesapeake Ceramics Large Lid Master listing; Nasco AMACO Lid Master listing; Kemper Tools Throwing collection and AL8, AL10, AL12 and CA10 product pages; Aardvark Clay calipers and shrinkage rulers listings; JB Tools Kemper AL10 listing; Blick calipers category, Richeson Steel Calipers and Potter's Select Wooden Caliper Set listings; Cromartie Hobbycraft Potter's Select set listing; Ceramic School calipers article. Research-based comparison, no hands-on testing. Specs checked October 2026.