What Size Round-Over Bit for 1 Inch Wood? (3/8″ to 1/2″)

For 1-inch wood, use a round-over bit with a 3/8″ to 1/2″ radius — roughly half the board thickness — unless you want a subtler edge, in which case drop to 1/4″. Undersize the bit and the edge looks thin on furniture; oversize it and you can round straight through a narrow rail. This guide covers what bit “size” actually means, a radius chart by wood thickness, and the exact router steps for a clean pass on 1-inch stock.

What “Bit Size” Actually Means on a Round-Over Bit

A round-over bit’s stated size is the radius it cuts into the wood — not a separate diameter measurement. A 1/2 inch round-over bit, from Freud, Amana, or any other maker, removes a quarter-circle profile with a 1/2 inch radius. Several older sizing charts online list “bit size” and “radius” as two different numbers on the same row — they’re the same measurement, and treating them as different is a common source of picking the wrong bit.

Round-over bits are bearing-guided: a ball-bearing wheel at the tip rides along the edge of the board while the carbide cutter removes material above it, so the depth of cut is set automatically by the bearing rather than by how far you plunge the router. That’s what lets you rout a consistent radius in one pass without a fence. It’s one of several profile bits worth having in your router and hand tool kit.

How to Pick the Right Radius for 1-Inch Wood

The common rule of thumb among router bit makers is to size the radius at roughly half the wood’s thickness for stock up to about 1 inch, then adjust up or down for the look you want. Measure your actual stock first — nominal “1-inch” boards from a lumberyard often mill out closer to 15/16″ or 7/8″, which still falls in the same bit range.

Wood Thickness	Recommended Radius	Resulting Look
1/2″	1/8″ – 3/16″	Light break on a sharp corner
3/4″	1/4″ – 3/8″	Standard cabinet/shelf edge
1″	3/8″ – 1/2″	Substantial, proportional furniture edge
1″ (both faces)	1/2″ on each face	Full bullnose, no flat shoulder

📊 Manufacturer sizing convention: Freud and Amana — two of the largest router bit makers — both catalog round-over bits directly by radius (their 1/2″ radius bits are literally named “1/2 Radius Rounding Over Bit”). There is no separate diameter spec to look up.

Working with 3/4 inch stock instead? The radius math changes — see our dedicated round-over bit guide for 3/4 inch wood for that specific range.

1/4″ vs 3/8″ vs 1/2″: Which Radius Look Do You Want on 1-Inch Stock?

All three sizes are valid choices for 1-inch wood — the right one depends on how much of the square edge you want to keep versus round away.

• 1/4″ radius: leaves a visible flat shoulder above and below the curve. Reads as a light detail rather than a rounded edge — good for shelving and cabinet doors where you don’t want the edge to dominate.
• 3/8″ radius: the middle ground. Removes noticeably more material with a smaller shoulder, common on tabletop edges and stair rail caps.
• 1/2″ radius: the largest practical radius for 1-inch stock on a single face. Routed on one face only it leaves a quarter-round profile with almost no shoulder; routed on both faces (see the FAQ below) it produces a full bullnose.

“On 1-inch stock I default to a 3/8-inch radius for most furniture edges. A full 1/2-inch reads great on a tabletop, but on a drawer front or a narrow rail it removes enough material that the piece starts to look thin.”

How to Round Over 1-Inch Wood With a Router

1. Measure the actual stock thickness: confirm with calipers rather than trusting the nominal “1 inch” label — rough or S4S lumber often mills closer to 15/16″, which still falls in the 3/8″–1/2″ radius range.
2. Mount the bit and zero the bearing: install the round-over bit and lower the router until the bearing sits flush with the wood’s face, then confirm it spins freely against the edge before cutting.
3. Take a light first pass: especially across end grain, run a shallow pass first to establish a clean line and reduce tear-out before the bearing is doing the full-depth cut.
4. Rout the full profile: guide the router at a steady pace with the bearing riding the edge; on hardwood, two lighter passes control chatter better than forcing one heavy pass.
5. Sand out mill marks: hand-sand the rounded edge with 150 then 220 grit to remove bearing chatter or light burn marks before finishing.
6. Repeat on the opposite face only for a full bullnose: flip the board and rout the second face if you want the two curves to meet in the middle (see the FAQ below) — skip this step for a standard single-radius edge.

Don’t have a router at all? Our guide to rounding wood edges without a router covers five hand-tool methods that get a similar result more slowly.

Common Mistakes When Rounding Over 1-Inch Stock

• Reusing a 3/4-inch-stock bit: a 1/4″ radius sized for 3/4″ material reads as too thin and dainty once it’s on a full 1-inch edge — size up to 3/8″ or 1/2″ for proportion.
• Skipping the bearing-height check: if the bearing isn’t flush with the face before cutting, the bit can gouge into the surface instead of following the edge cleanly, especially on the first pass.
• Feeding the router the wrong direction: feed against the bit’s rotation for the main cut; only use a light climb cut (with the rotation) as a shallow finishing pass to knock down tear-out, never for the full-depth cut, since a full climb cut increases kickback risk.
• Skipping a scrap test: grain direction and density vary enough between species (and even between boards) that the same bit can tear out on oak but cut cleanly on pine — always test the exact bit and depth on an offcut first.

Frequently Asked Questions

What size round-over bit should I use for 1-inch wood?

For 1-inch stock, use a bit with a 3/8″ to 1/2″ radius — close to half the material’s thickness. A 1/2″ radius removes enough material to round the full edge into a near-quarter-circle profile; 3/8″ leaves a small flat shoulder on each face for a more traditional look.

Does “bit size” mean the radius or the diameter on a round-over bit?

The stated size is the radius the bit cuts, not the diameter of the bit body. A “1/2 inch round-over bit” — from Freud, Amana, or any other maker — cuts a 1/2 inch radius. Some online charts mix this up and list “bit size” and “radius” as two different numbers on the same row; they’re the same measurement.

Can I use a 1/2 inch round-over bit on 1 inch wood, or is that too big?

It’s not too big — a 1/2″ radius is the largest that fits cleanly on 1″ stock, since two of them routed on opposite faces exactly equal the board’s thickness. A larger radius would need to remove material beyond the edge and isn’t practical on 1-inch material.

What happens if I round over both edges of 1-inch stock with a 1/2 inch bit?

Routing both faces with a 1/2″ radius bit makes the two curves meet in the middle, producing a full bullnose (half-round) edge with no flat shoulder left. This is a common look for tabletop edges, handrails, and stair nosing.

Do I need a router table for this, or can a handheld router work?

A handheld router works fine on 1-inch stock as long as the base has enough bearing surface to stay flat on the board. A router table just adds stability for longer or narrower pieces — see our Bosch 1617EVS router setup guide for bit-depth settings either way.

Conclusion

For 1-inch wood, a 3/8″ to 1/2″ radius round-over bit gives a proportional, furniture-grade edge — remember that the bit’s stated size is the radius itself, not a separate diameter. Measure your actual stock, pick the radius that matches the look you want from the chart above, and always run a test pass on scrap before cutting your final piece.

Working on plywood instead of solid stock? Edge grain behaves differently under a round-over bit — see our guide on rounding edges on plywood for the adjustments that prevents chip-out on veneer layers.