Chainsaw Chain Information


Saw chain used on chainsaws come in a wide variety of lengths, types, and features.

When you must replace your existing chain, the best thing to do is to simply bring your complete chainsaw to us or at the very least, the chain. We can examine it and provide you with the correct solution in one trip. Otherwise you need to know the size of the chain your saw can use. You might think suppliers like ourselves simply need to know the length of the chain but there is more to it than that. If you have the right measurement information, a replacement can be determined quickly. Without the information, it can take a bit longer because there are a few variables that must be measured to determine the correct replacement chain. The diagram below helps to define what the parameters are for a chain.

Once the correct size of chain has been determined, then the type of chain must still be selected. For example, one parameter that would normally be selected is an anti-kickback safety chain. But for some experienced users, they may want a non safety chain.

To determine the correct chain for your saw, there are three numbers that must be figured out: pitch, gauge, and the number of drive links.

chain pitch

The Pitch parameter is the distance between any three rivets. Measure this number and then divide by two, to determine the pitch. For example, if the center to center distance between three rivets equals 3/4 of one inch, or .750 inches, then the Pitch is .750 / 2 = .375 And .375 converted back to a fraction is 3/8, thus you now know this chain is a 3/8's chain. The usual sizes are 1/4", .325", 3/8" and .404". It is obvious here that some of the sizes are noted in fractions and some are noted in decimal form. This is not a mistake in how this artical is written. It is simply how the industry has defined these. Otherwise we could say 1/4" is .250 and 3/8 is ..375. Or convert them all to fractions.

The gauge is another important number. This is the width of the driver which is the part that sits down in the groove of the chain bar. If the driver is too narrow, it can jump out of the bar easily. If it is too wide and happens to fit into the channel in the bar, it will have too much drag and cause other problems. Assuming the bar is not bent or damaged and the drivers on the chain are not nicked or damaged, the drivers should travel smoothly without slop in the chain bar channel.

The gauge of a driver must be accurately measured with calipers or other gauge-sizing tool made for the purpose. If you do not have these kind of tools, the best thing to do is to have us measure this for you. This is something that stores such as a multi-product lumber store is not likely to have someone with the knowledge, experience that can do this for you. Common sizes for the driver gauge are .043", .050", .058", and .063 with the most common size being .050. The picture below shows the gauge of a driver on this particular chain is per the caliper tool, .050 inch (1.27mm).

Chain driver measurement

Another way to measure the gauge of a driver is with a template-style tool such as the one seen here in the next picture below. While it is hard to see the raised print next to each slot, this chains driver did not correctly the other three slots that are clearly too small or too large. Like the previous example, this chain also had .050 inch (1.3mm) gauge drivers.

ragan equip_stihl template

Please note that sometimes the driver thickness, or gauge may measure fine. If the driver's overall shape however has been worn from use and/or improper chain oiling, the driver may be so worn down as to make it time to replace the entire chain. If one driver is worn badly, the others can be checked but it is usually the case that all or at least many other drivers will also be bad. Likewise the height of the cutters may be worn down or sharpened so many times, that may also indicate it is time to replace with an all new chain. Be safe! Chains are fairly inexpensive. Your safety and well being are worth a lot more. Your saw and saw bar will appreciate the use of good chains at all times too.

As noted above, in all cases it is best if you bring at least your old chain into our store. It is better if you bring your entire chainsaw, in case we need to look at it to determine additional information. We stock the more common chain types and may have a chain on the shelf or can make one from scratch.

For existing chains that are still in good shape, we can sharpen these for you for very little cost @ $6 a chain or $8.50 if still mounted on your saw. This service is done on Tuesdays and Fridays before we open for regular business. So if you want a chain sharpened on Tuesday, you need to get it in our hands by at least the day before. Otherwise if you bring a chain in during business hours on Tuesday for example, your chain will be sharpened on Friday.

We can also examine your chain bar and recommend if we should service it or tell you what a replacement would cost. Usually bars are okay but they can wear down and may have been bent during use. These can lead to dangerous situations so always examine, or have us examine your bar to make sure it is as safe as it can possibly be.

AND PLEASE USE QUALITY CHAIN BAR OIL! Regular motor oil is NOT a substitute.

Motor oil viscosity will mean your chain and bar will spray much of it into the air. Not necesarily visible when it sprays like this. You will be breathing toxic motor oil. The environment and even the very tree you might be trimming will suffer too. Eventually your chain bar, cog gear, oil pump and chain will fail far earlier than normal use and proper lubrication. Do the right thing for you and your saw.

If you are interested in additional information, a great place to start is at this link: STIHL chain saw chain