Circular saw blade arbor size: which blade fits your saw

01What is a circular saw arbor, and what does arbor size mean?

The arbor is the spindle the blade mounts on, and the arbor size is the diameter of that spindle, which the hole in the centre of the blade (the bore or arbor hole) must match exactly. The blade is clamped between the saw's own inner and outer flanges by the arbor bolt, and the saw's manual names both the hole size and its shape.

Two hole shapes exist on handheld saws. Most sidewinder saws use a round arbor; many worm-drive saws use a diamond-shaped one. Makita's 5007MG manual and DeWalt's DWE575 manual both say to use only blades with the correct arbor-hole size and shape, because a mismatched blade runs off-centre and can cause loss of control. The US workplace rule for woodworking machinery says the same thing in regulatory language: blades must be machined to fit the arbor.

Arbor size is only one of three fit checks. The other two are blade diameter and rated speed, both covered below. A blade that slides onto the spindle can still be the wrong blade for the saw, which is why Makita's own manuals warn that an accessory attaching to a tool does not make it safe to use.

02What arbor size do circular saw blades use?

In the US, circular saw blades use a 5/8 in arbor for every common handheld size, with compact trim blades as the main exception. Diablo, Makita, Milwaukee and DeWalt all list that hole for 7-1/4 in blades and saws, and Diablo and Makita list the same 5/8 in hole for 6-1/2 in cordless saws and their blades.

The same hole carries on to the larger blades used in table and miter saws: Diablo and Milwaukee list 5/8 in for the next size up, and Diablo, Makita and DeWalt list 5/8 in for the common miter and table saw size, until the largest miter-saw class switches to a 1 in hole. Compact saws go the other way: Diablo's trim blades and Milwaukee's M12 FUEL compact saw use a 10 mm arbor, so a standard blade from a full-size saw will not fit them. Two less common sizes sit outside that pattern. Diablo lists a 1/2 in arbor for its small blades made for saws such as the Porter-Cable Saw Boss, so those saws take neither the standard nor the trim-saw hole. At the other end, the large dry-cut metal saw blades from Diablo and Milwaukee use a 1 in arbor, the same hole as the biggest miter-saw blades but on a blade built for a dedicated metal-cutting saw. Sizes for the bigger bench saws are covered in more depth in the guides to table saw arbor sizes and miter saw blade sizes.

The table below lists each US diameter with its arbor, plus one example of a blade's marked maximum speed next to a saw's no-load speed, all from manufacturer specifications.

03Which blades fit popular circular and track saws?

Each saw's maker states the blade diameter and arbor it accepts, and the table below collects those published figures for the circular and track saws in the AccessoryFit tool database. Where a maker does not state a value, the table says so rather than filling it in. The same data, searchable by model, sits behind the accessory finder.

Two saws with the same blade diameter can still take different blades. The Makita XSH03Z and the Makita SP6000J both take 6-1/2 in blades, but the first has a 5/8 in arbor and the plunge-cut track saw has a 20 mm arbor. A track-saw blade and a framing blade of the same diameter are not interchangeable for that reason alone. Among 7-1/4 in saws, the Makita 5007F and Milwaukee 2731-20 both list a 5/8 in round arbor, while the DeWalt DWS535B worm-drive saw needs a diamond-arbor blade.

04What is the diamond knockout, and when do you remove it?

The diamond knockout is a pre-cut diamond-shaped centre in some blades that is knocked out so the blade fits a worm-drive saw's diamond arbor. Worm-drive saws such as the SKILSAW SPT77WML and the DeWalt DWS535B use a diamond-shaped arbor, and DeWalt's DWS535B manual says only blades with a diamond-shaped arbor centre can be used on that saw. DeWalt's DW3508 metal-cutting blade is one example sold with a diamond knockout for worm-drive saws.

DeWalt's manual adds that the knockout must be removed before the blade goes on, and that a blade should never be installed with the knockout still in place, because without full engagement the blade can contact parts of the saw. The same manual asks for care when knocking the centre out.

Not every worm-drive-style saw uses a diamond. The Makita 5377MG hypoid saw lists a 5/8 in arbor, and Makita's 5377MG manual describes a two-sided inner flange whose sides suit 5/8 or 13/16 in blade holes. Makita warns that mounting the flange on the wrong side causes dangerous vibration. Check the manual of your own saw rather than assuming from its gearbox style.

05Can you use a reducer bushing or arbor adapter on a circular saw?

Only the ring, flange side or adapter that the saw's own maker supplies for that bore is acceptable; saw manuals say not to use spacers to make a blade fit. DeWalt's DWE7491 table saw manual says not to use any spacers to make a blade fit onto the spindle. Makita's HS7611 manual covers saws designed with an arbor-hole ring and warns that the ring must match the blade's hole, because the wrong ring can let the blade move and vibrate severely.

Factory adapters do exist. DeWalt's DWS780 miter saw has a 5/8 in spindle and DeWalt supplies its own adapter for blades with a 1 in hole. Makita's two-sided 5377MG flange, described above, is another manufacturer-designed solution for two hole sizes.

Aftermarket reducer bushings sold separately are a different matter. No saw manufacturer source in the AccessoryFit fact base approves third-party bushings, and the no-spacers instruction points the other way. The practical rule follows: if the blade's hole does not match your saw and the saw's manual does not list a ring or adapter for that hole, buy a blade with the correct hole instead.

06Is a blade safe at your saw's RPM?

A blade is safe for speed when the maximum RPM marked on it equals or exceeds the no-load speed marked on the saw. DeWalt and Makita manuals both state this rule, and the general accessory rule behind it is that an accessory run faster than its rated speed can break and fly apart.

In one published example the check passes with room to spare. Diablo marks its 7-1/4 in wood blades for a maximum of 8000 rpm, while the Makita 5007F runs at 5800 rpm and the Milwaukee 2731-20 at 5000 rpm. The check matters more when a blade crosses between tool types. In the US table above, the larger blades meant for miter and table saws carry lower marked maximums than the handheld sizes, so a blade borrowed from a bench saw needs its marking read before it goes on anything else.

The marking on the blade itself is the figure that counts. The maximum speeds in the tables are for the named blades only, and two blades of the same diameter can carry different ratings, as the two Diablo 6-1/2 in blades in the US table show.

07Can a 7-1/4 in blade go on a 6-1/2 in saw?

No. Both sizes share a 5/8 in arbor, but manufacturers require the exact blade diameter marked on the saw, because a wrong-size blade may not be guarded properly. A common belief is that a matching arbor makes any blade a fit; Makita's HS7611 and LS1019 manuals say an incorrectly sized blade may affect guarding, and DeWalt's DWE575 manual tells owners to use the correct size blade. OSHA also expects the saw frame to limit the blade size that can be mounted.

Going smaller is no better. DeWalt's DWS713 manual says never to use a smaller blade, because it will not be guarded properly. A portable circular saw must have guards above and below the base plate, and the lower guard must return automatically and instantly to cover the blade when the saw comes out of the work.

Even the correct diameter leaves blade exposed below the work if the depth is set carelessly. Germany's construction-industry accident insurer, BG BAU, in its 2021 guidance for hand-held and site circular saws, says the blade should project no more than 10 mm (about 3/8 in) below solid timber, so the depth is set to the board being cut rather than left at the saw's maximum. Exposed teeth are what injure hands. Using CPSC's NEISS emergency department data for 2024, AccessoryFit estimates that about 9,500 injuries involving portable circular saws were treated in US emergency departments that year, and that 10.8% of them were diagnosed as amputations.

08Which direction does a circular saw blade go on?

On a handheld circular saw, the blade goes on with the teeth pointing up at the front of the saw, so the arrow printed on the blade matches the rotation arrow on the guard. Makita's 5007MG manual and DeWalt's DWE575 manual both give this instruction.

Circular saw blade direction differs by saw type, which is why a blade can look backwards when it is moved between tools. A table saw blade is mounted with the teeth down at front, and on a miter saw DeWalt's manuals put the teeth at bottom toward back. All three follow the same underlying rule: the arrow on the blade matches the rotation arrow on the saw's guard.

Unplug the saw or remove its battery before changing the blade, then fit the saw's own inner flange, the blade, the outer flange and the bolt in the order the manual shows. Makita's manuals add a maintenance point that affects how a correctly mounted blade behaves: hardened gum and pitch slow the saw and raise kickback risk, so the blade should be cleaned off the saw with gum and pitch remover, hot water or kerosene, never gasoline. If cuts scorch even with a clean, correctly mounted blade, the guide on why saw blades burn wood works through the other causes.

09How do US arbor sizes compare with European bores?

US blades are sized in inches and most have a 5/8 in hole, while European blades are sized in millimetres with bores of 20 mm or 30 mm. Both metric bores are larger than the US hole, so a European blade would sit loose on a US spindle, which is the off-centre condition the manuals forbid.

Bosch's GKS 190 hand-held saw takes a 30 mm bore, and Bosch's GCM 12 SDE mitre saw takes 30 mm as well. Makita's UK specifications for the HS7611 and HS6601 list two bores, depending on the country version, so a European owner needs to check the plate on the saw rather than the model number alone. Makita also sells the same model numbers in both markets with different blades: the European LS1019L takes a metric blade with a 30 mm bore, while the US version takes an inch blade with a 5/8 in hole.

Track saws are where a metric bore turns up on US saws. Makita's US track saws, the SP6000J and XPS01Z, list a 20 mm arbor, so their blades are not interchangeable with ordinary 6-1/2 in framing blades. Metric conversions of inch sizes also vary slightly between makers: DeWalt and Makita give different millimetre figures for the same inch blade, and the US table follows DeWalt's figures.

One metric size is easy to confuse with an inch size. DeWalt prints 10 in (254 mm) on its blades and manuals, so the two labels describe the same blade. Makita's EU specifications list a separate 260 mm size for European mitre and table saws such as the EU LS1019L and LS1040, with a 30 mm bore; per Makita, that is a different blade, not a relabelled inch size.

10When does a blade not fit, even if the hole looks right?

A blade does not fit whenever any one of the three checks fails: diameter, hole size and shape, or speed rating. These are the cases the manufacturer manuals on this page call out:

• Diameter differs from the saw marking. Even with the right arbor, a wrong-size blade may not be guarded properly.
• Round hole on a diamond arbor, or the reverse. The blade runs off-centre and can cause loss of control.
• Metric bore on an inch spindle. A 20 mm or 30 mm blade is loose on a 5/8 in arbor unless the saw maker supplies a ring for it.
• Blade speed rating below the saw's no-load speed. Check this every time a blade moves between tool types.
• Worn or wrong flanges, washers or bolts. Makita says to use only the parts designed for that saw.
• Wrong ring or flange side. Both Makita warnings on rings and two-sided flanges describe severe vibration.

A blade can also fit perfectly and still be the wrong tool for the job. Demolition cuts through nail-embedded framing, for example, are covered in the guide to reciprocating saw blades built for demolition.

11How do you check blade fit on a saw not listed here?

Five checks, in this order, confirm whether a blade fits a saw that is not in the table above. Each uses the markings on the saw, its manual and the blade itself.

1. Disconnect power. Unplug the saw or remove the battery before handling the blade or flanges.
2. Read the saw's blade diameter and no-load speed. Both are marked on the saw's nameplate or guard and listed in the manual's specifications.
3. Confirm the arbor size and shape. The manual's specifications or blade-changing section states the hole size and whether the arbor is round or diamond, and lists any ring or adapter the maker supplies.
4. Read the blade's markings. Check its diameter, bore and maximum RPM. The bore must match the arbor, and the maximum RPM must equal or exceed the saw's no-load speed.
5. Mount it the right way round. Fit the saw's own flanges and bolt with the teeth pointing up at the front and the blade arrow matching the guard arrow, then check that the lower guard closes freely.

12What else decides which blade to buy?

Once the arbor, diameter and speed checks pass, the remaining choice is about the cut: tooth count, grind, hook angle and kerf decide whether a blade rips fast, crosscuts cleanly or handles laminate. Those attributes are covered in the guide on how to choose a circular saw blade, and the circular saw blade selector narrows blades by material, teeth and size. For sheet goods, the shortlist of circular saw blades for plywood applies the same fit rules to specific products.

Every blade type on the site is grouped under the saw blade guides, and fit rules for drills, grinders, sanders and routers sit alongside this page in the compatibility guides.

13Questions readers ask