What Size Round-Over Bit for 3/4″ Wood? (1/4″ to 3/8″)

A 1/4″ to 3/8″ radius round-over bit is the right size for 3/4-inch wood — go with 1/4″ for a subtle edge break, 3/8″ if you want more of the square shoulder rounded away. Sizing up to a 1/2″ radius on 3/4″ stock removes so much material the edge reads as a quarter-round, not a round-over. This guide covers picking the right radius, safe router speeds by bit size, and how to rout the profile cleanly.

Working with a different thickness? See our dedicated guide for round-over bit sizing on 1-inch wood, where the radius range shifts up to 3/8″–1/2″. Routing 3/4-inch plywood instead of solid stock? Rounding edges on plywood covers the extra care veneer layers need to avoid chip-out.

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

A round-over bit’s “size” is its radius — the radius of the curve it cuts into the edge — not the overall diameter of the bit body. A 1/4″ round-over bit cuts a 1/4″ radius curve; the cutting head itself measures about 1/2″ across (diameter is always double the radius). Mixing the two up is the single most common mistake when buying a bit online.

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 by the bearing, not 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 the more useful profile bits to keep in a router and hand tool kit.

Bit Radius	Cutting Diameter	Good Fit for 3/4″ Wood?	Typical Use
1/8″	1/4″	Yes — light detail	Small decorative edges, fine trim
1/4″	1/2″	Yes — best all-around	General-purpose edges, cabinet doors, shelving
3/8″	3/4″	Yes — fuller curve	Tabletop edges, rounded corners and trim
1/2″	1″	Marginal — oversized on one face	Better suited to 1-inch-plus stock
5/8″ – 1″	1 1/4″ – 2″	No — too large	Thick stock (1″+), bullnose posts

How to Pick the Right Radius for 3/4-Inch Wood

The working rule of thumb: keep the bit’s radius at or under half your stock’s thickness. Half of 3/4″ (0.75″) is 3/8″ (0.375″), so 3/8″ is the practical ceiling for a single-face round-over on 3/4″ material — anything larger and the curve no longer leaves a visible flat shoulder, which starts to look like a mistake rather than a design choice. Most general-purpose work — cabinet doors, shelf edges, drawer fronts — uses a 1/4″ radius by default and only sizes up to 3/8″ for edges meant to stand out, like a tabletop perimeter.

• Don’t buy by the number alone: a search for “3/4 round-over bit” can surface bits like the Freud 34-128, which is a 3/4-inch radius bit — sized for 1.5-inch-plus stock, not 3/4-inch wood. Match the radius to roughly half your material’s thickness, never to the thickness number itself.
• Measure the actual stock, not the nominal size: S4S lumber sold as “3/4 inch” often mills to 23/32″ or slightly under — check with calipers before committing to a 3/8″ radius, which leaves very little shoulder margin for error on thinner-than-nominal stock.
• Router speed rarely matters at this size: every bit radius appropriate for 3/4″ wood (up to 1/2″ radius, 1″ cutting diameter) falls under the 1-inch-diameter threshold where full router speed — 22,000–24,000 RPM — is safe. You only need to slow down toward 18,000–22,000 RPM once you move to the larger 3/4″–1″ radius bits used on thicker stock, where tip speed starts causing burning and chatter.

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

All three radii are legitimate choices for 3/4-inch wood — the right one depends on how much of the square edge you want to keep versus round away.

• 1/8″ radius: barely breaks the corner. Reads as a safety chamfer more than a rounded edge — good for small boxes, trim, and edges where you don’t want the profile to be noticed.
• 1/4″ radius: the default for a reason. Leaves a clear flat shoulder above and below a visible curve — the standard look for cabinet doors, shelving, and most general-purpose edges.
• 3/8″ radius: the practical maximum for 3/4″ stock on a single face. Removes noticeably more material with a thin shoulder, common on tabletop edges and stair rail caps where you want the curve to dominate.

“On 3/4-inch stock I reach for a 1/4-inch radius by default and only go to 3/8-inch when the piece is meant to be handled a lot, like a tabletop edge or a stair cap — the fuller curve feels better under a hand and hides small dents better than a crisp 1/8-inch break.”

How to Round Over 3/4-Inch Wood With a Router

1. Measure the actual stock thickness: confirm with calipers rather than trusting the nominal “3/4 inch” label — S4S lumber often mills a hair under, which still falls comfortably in the 1/4″–3/8″ 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 carries the full-depth cut.
4. Rout the full profile: guide the router at a steady pace with the bearing riding the edge; two lighter passes control chatter better than forcing one heavy pass on hardwood.
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 hand-tool methods that get a similar result more slowly. Setting up a dedicated router instead? Our Bosch 1617EVS router setup guide covers bit-depth settings, and our router table guide covers mounting options if you want the extra stability of a table for longer boards.

Common Mistakes When Rounding Over 3/4-Inch Stock

• Buying a bit sized for the wood’s thickness instead of its radius: as covered above, a “3/4-inch” labeled bit is often a 3/4-inch radius bit meant for much thicker stock — always check the radius number, not the wood thickness, against the listing.
• Sizing up out of proportion: a 1/2″ radius on 3/4″ stock leaves almost no flat shoulder on one face — fine for a bullnose if you round both faces, but it looks like a rounding error on a single-face edge.
• 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 density varies 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 3/4-inch wood?

Use a 1/4″ to 3/8″ radius round-over bit for 3/4-inch wood. A 1/4″ radius is the standard, all-purpose choice; step up to 3/8″ only when you want a fuller curve, like on a tabletop edge. Staying at or under half the stock’s thickness keeps a visible flat shoulder on the edge.

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

It means the radius. A “1/4-inch round-over bit” cuts a 1/4-inch radius curve; the bit’s actual cutting diameter is double that, about 1/2 inch. Confusing the two — especially when a listing describes the bit by a “3/4-inch” number that’s actually the radius — is the most common bit-buying mistake for this project.

Can I use a 1/2 inch round-over bit on 3/4 inch wood, or is that too big?

It’s workable but oversized for a standard single-face edge — a 1/2″ radius removes two-thirds of the material on one face of 3/4″ stock, leaving almost no flat shoulder. It reads better as a deliberate design choice than an accident, and it’s the right size if you plan to round over both faces for a full bullnose rather than one face alone.

What happens if I round over both edges of 3/4-inch stock with a 3/8 inch bit?

Rounding both faces with a 3/8″ radius bit — three-quarters of the stock’s 3/4″ thickness — produces a full bullnose profile where the two curves meet with little to no flat edge left in the middle. This is the standard bullnose approach for tabletop edges, handrails, and stair caps on 3/4-inch material.

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

A handheld router works fine on 3/4-inch stock as long as the base has enough bearing surface to stay flat on the board. A router table adds stability mainly for longer or narrower pieces where a handheld router would tip or wobble — either method produces the same radius since the bearing, not the setup, controls the depth of cut.

Conclusion

For 3/4-inch wood, a 1/4″ radius round-over bit covers most general-purpose edges, with 3/8″ as the practical upper limit for a fuller curve on a single face. Match the radius to roughly half your stock’s actual thickness — not to the thickness number itself — check the bearing height before cutting, and test on scrap first since grain density affects tear-out more than bit size does.