The depth that a circular saw can cut at, is dependent on the size of blade that the saw uses. The bigger the blade the saw has then the deeper the saw will be able to cut. Circular saw blades are measured by diameter and typically you will see something like a 185 mm blade.

This blade fits on the circular saw attached to the arbor of the saw through the central bore hole of the blade. The size of that hole can also vary and for a standard 190 mm blade is usually around 22mm.

The actual cutting depth of a circular saw blade is usually about one third of the size of the diameter of the blade on a straight cut. On a 45 degree cut it is about one quarter the size of the blade size. Many buyers don't realise this when they are buying a circular saw and can easily end up buying the wrong size for the job they want to use it for.

The simplest way to understand this is that the distance between the circular saw base (shoe) and the bottom of the blade is the real depth that the saw can cut.

We have completed a comparison table just below that shows the circular saw size. In the columns beside that we have shown the depth of cut at 90 degrees and at 45 degrees. A 90 degree cut is basically a straight cut through the wood. A 45 degree cut is usually called a bevel cut (sometimes a mitre cut) and that will always be a smaller depth.

parts of a circular saw blade diagram

Circular Saw Cutting Depth Comparison Table

These depths are for standard circular saws irrespective of whether they are electric or cordless.

Circular Saw Size

Depth of cut at 90 degrees

Depth of cut at 45 degrees

150 mm (5.9")

0-48 mm (1.9")

0-36 mm (1.4")

160 mm (6.3")

0-55 mm (2.16")

0-38 mm (1.49")

165 mm (6.5")

0-57 mm (2.24")

0-41 mm (1.61")

185 mm (7.28")

0-65 mm (2.55")

0-45 mm (1.77")

190 mm (7.48")

0-66 mm (2.59")

0-46 mm (1.81")

235 mm (9.25")

0-85 mm (3.34")

0-56 mm (2.2")

270 mm (10.63")

0-101 mm (3.97")

0-71 mm (2.79")

The cutting depths shown here are a very good working average. They may vary slightly depending on the brand of circular saw you own as the actual construction of the saw also has a minor impact on the depth.

Mini Circular Saw Cutting Depth Comparison Table

As well as the standard circular saw sizes, you can also buy small (mini) circular saws. The depths shown below are for mini circular saws irrespective of whether they are electric or cordless.

Circular Saw Size

Depth of cut at 90 degrees

Depth of cut at 45 degrees

85 mm (3.35")

0-27 mm (1.06")

n/a

115 mm (4.53")

0-43 mm (1.7")

0-26 mm (1.0")

125 mm (4.92")

0-48 mm (1.9")

0-28 mm (1.1")

The cutting depths shown here are a very good working average. They may vary slightly depending on the brand of mini circular saw you own as the actual construction of the saw also has a minor impact on the depth.

circular saw cutting depth

Depth Adjustment on a Circular Saw

Almost every circular saw comes with depth adjustment. Usually this is set using a lever and a guide. It allows you to set the circular saw to a specific depth when cutting. Usually this starts at zero and can be adjusted up to the maximum depth. When I am using any circular saw this is one of the most important things I consider. If you are just doing basic cutting of timber it doesn't really matter. For plunge cuts it is vitally important to be able to adjust the cutting depth.

Can a Circular Saw cut a 2 x 4" timber

Any circular saw size of 160mm (6") or above can cut a depth of 2". There is really no limit on the width of the timber when using a circular saw. The 150mm circular saw size or mini circular saws will not be able to cut a 2" depth. 2" x 4" is used a lot for making walls and for struts, and this is what I would make a lot of. Having the bigger size circular saw certainly makes a difference.

Can a Circular Saw cut a 4 x 4" Post?

The only circular saw that can straight cut a 4 x 4" post is a 270mm circular saw. The Makita HS0600/2 240V 270mm Circular Saw is the one that we would recommend for doing work like that. Large saws like this are not cheap. They will save you time if you have a lot of cutting to do, but for a few posts we would use a basic hand saw.

Common uses of a Circular Saw

A circular saw is a general purpose saw and is mainly use to make straight cuts in timber. They are simply just a fast way of cutting wood rather than using a hand saw. They can also make bevel cuts in wood. By changing the blade you can also cut plastic and thin metal such as aluminium. Most commonly though, people buy these as a fast way to cut decking boards, floorboards, fencing, rough sawn timber and planed timber.

They are very good in making long cuts in thicker materials. They can cut chipboard, plywood, wooden beams, and hardwood flooring.

If you want to use a circular saw to cut laminate worktops read our article here.

Buying Circular Saw Blades in the UK

This can get really confusing for UK buyers. The reason for that is the use of both imperial and metric measurements. Many DIY stores and people in the building and construction industries still refer to timber as 2 x 4" and 4 x 4". When you go to a store like B&Q you won't find those sizes. Instead they will be in metric shown as 50 x 100mm and 100 x 100mm.

Those measurements refer to rough sawn timber. If that timber has been planed to give a smooth finish then it will be slightly smaller again. Our advice is to measure the depth of the wood you need to cut, check that against our chart above, and then buy or rent out the right size of circular saw.

In the UK, circular saw blades are sold in mm. Circular saws are also sold in mm sizes so stick with those. If needs be, convert inches to mm to make sure you get the right size of saw. You do of course need to pick the right size of blade for your saw. You can use smaller blades on larger circular saws by using reducing rings, also known as adapter rings. You can't use a larger blade on a smaller saw.

Summary of Circular Saw Depths

The depth of cutting when using a circular saw is often misunderstood. We think manufacturers should have to show this on the blade to make buyers aware. Currently all you really see is the diameter size of the blade. the number of teeth, RPM and some safety instructions. We don't think it would be hard to add in 2 cutting depths as guidance.

The reality is that they don't, so you have to figure that out for yourself. The important thing though is to make sure to buy the size of blade that matches your saw. You can also buy a slightly smaller blade for your saw and then used reduction rings to make the blade fit snugly.

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