Medium-duty chainsaws in the 50 to 60 cubic centimeter class commonly accept a 72-drive-link chain on a 20-inch bar. These saws—popular among homeowners, farmers, and rural property owners—typically use a 3/8-inch pitch chain with a 0.050-inch gauge. Brands such as Stihl, Husqvarna, and Echo offer models that match this configuration, though the exact specifications can vary between manufacturers and even between different bars on the same saw model.

Before purchasing a replacement chain, you must verify four key factors: the chain pitch, the bar gauge, the drive link count, and the bar mount type. A 72-link chain designed for one pitch or gauge will not fit a bar expecting a different configuration, even if the bar length is identical. This article explains what each specification means, which chainsaws commonly use this combination, and how to confirm compatibility before you buy.

Understanding the Question: What Do ’72 Link’ and ’20-Inch Bar’ Mean?

A labeled diagram illustrating a chainsaw bar and chain with drive links and cutting length visible.

When someone asks what chainsaw takes a 72-link chain on a 20-inch bar, they are looking for either a replacement chain match or confirmation that their saw uses this configuration. To answer the question properly, you need to understand what these terms actually describe.

A drive link is the individual tooth-like component on the bottom of a chainsaw chain that engages with the sprocket to move the chain around the bar. The drive link count represents the total number of these components on a complete chain loop. A chain with 72 drive links will have 72 of these engagement points arranged in a continuous circle around the bar and sprocket.

The 20-inch measurement refers to the usable cutting length of the bar, not the total physical length of the bar from tip to mount. This is an important distinction because bars marketed as “20-inch” may have slightly different actual lengths depending on the manufacturer, which can affect the required drive link count.

The reason the same 20-inch bar can use different link counts comes down to three variables: the chain pitch, the bar gauge, and the specific bar mount configuration. Pitch determines how far apart the cutting teeth are spaced. Gauge determines how thick the drive links are, which must match the bar groove width. These factors combine to determine how many links fit around a given bar length.

Medium-duty gas-powered chainsaws in the 50 to 60cc range frequently use a 72-drive-link chain when equipped with a 20-inch bar. These saws strike a balance between power for moderate cutting tasks and manageable weight for homeowner and light professional use.

Models commonly associated with this configuration include several popular options from major manufacturers. The Stihl medium-frame saws in the Farm Boss and Rancher-style classes often use this combination when equipped with the standard 3/8-inch pitch, 0.050-inch gauge chain. Similar configurations appear across Husqvarna’s homeowner and farm-oriented models in the 50 to 60cc class. Echo’s medium-duty offerings in comparable displacement ranges also frequently use this setup.

The typical chain specification for these saws is a 3/8-inch pitch with 0.050-inch gauge and 72 drive links. This combination provides good cutting performance while maintaining chain speed and control suitable for the power output of mid-range saws.

However, you should note that the same bar length from different manufacturers—or even different bars from the same manufacturer—may require different link counts. Some 20-inch bars using 0.325-inch pitch chains may also use 72 drive links, while the same bar length with 3/8-inch pitch might require 70 links depending on the specific mount and groove configuration. Always verify your saw’s exact requirements rather than assuming based on bar length alone.

Understanding these four specifications will prevent you from buying the wrong chain. Each factor must match your bar and saw requirements.

Chain Pitch

Chain pitch refers to the distance between three consecutive rivets divided by two, measured in inches. The two most common pitches for mid-range saws are 0.325 inches and 3/8 inches. The 3/8-inch pitch is more prevalent on medium-duty saws because it offers a good balance of cutting speed and chain strength. The 0.325-inch pitch is slightly narrower and is often found on lighter-duty saws or specific bar configurations.

A 3/8-inch pitch chain will not physically fit a bar and sprocket designed for 0.325-inch pitch, and vice versa. The cutting teeth and rakers are also spaced differently, so using the wrong pitch would result in poor cutting performance or damage.

Bar Gauge

Bar gauge describes the thickness of the drive links, which must match the width of the groove in your guide bar. Common gauges are 0.043 inches, 0.050 inches, and 0.058 inches. Most medium-duty saws using a 20-inch bar with 3/8-inch pitch utilize 0.050-inch gauge.

If you install a chain with the wrong gauge, it will either be too loose (causing safety hazards and poor performance) or too tight (causing excessive wear and potential damage). The chain must fit snugly in the bar groove while still being able to rotate freely.

The drive link count must exactly match what your bar requires. For a 20-inch bar on a medium-duty saw, common counts include 70, 72, and occasionally other numbers depending on the specific bar and pitch combination. The link count is determined by the bar length, pitch, and gauge working together.

A chain with too few links will not reach around the bar. A chain with too many links will bunch up and potentially damage the bar or cause the chain to skip off the sprocket.

Bar Mount

The bar mount refers to how the bar attaches to the saw’s sprocket nose or clutch. Different manufacturers use different mounting systems, and some saws within the same brand use different mounts for different bar lengths. The mount affects how the chain sits in the bar and how the drive links engage with the sprocket.

Using a chain designed for a different mount type—even if the pitch, gauge, and link count appear correct—can result in poor chain retention or premature wear. Always confirm that your replacement chain is designed for your specific bar mount configuration.

Step-by-Step: How to Verify Compatibility Before Buying

Following these steps will help you confirm the exact chain specifications for your chainsaw before making a purchase.

Step 1: Locate Your Current Chain’s Specifications

Look at the side of your cutting chain where the manufacturer stamps the specifications. You will typically see a three-part code: pitch, gauge, and drive link count. For example, you might see “3/8 P .050 72” indicating a 3/8-inch pitch, 0.050-inch gauge, 72-drive-link chain.

If the chain has been heavily used or filed, the stamps may be worn. In this case, move to Step 2.

Step 2: Check Your Owner’s Manual

Your chainsaw’s owner’s manual lists the recommended chain specifications for each bar length the saw can accept. This information is specific to your model and accounts for the exact bar mount and sprocket configuration. The manual will typically list the chain size in the format “pitch-gauge-drive links” or similar.

If you do not have the manual, most manufacturers provide PDF versions on their websites if you search by model number.

Step 3: Measure Your Bar

Measure the cutting length of your bar from the tip to the point where it emerges from the saw body. This is the 20-inch or other length measurement. Do not measure the total physical length of the bar, as this will give you an incorrect number.

Compare this length to what your manual or current chain specifications claim. If they match, you have confirmation. If they differ significantly, you may have the wrong bar length or need to verify your measurements.

Step 4: Verify Pitch and Gauge

If you need to determine pitch and gauge without stamped information, you can measure them directly. For pitch, measure the distance between the centers of three consecutive rivets and divide by two. For gauge, measure the thickness of a drive link with calipers.

However, visual comparison with a known chain of the correct specification is often easier and more reliable for most users.

Count the drive links on your current chain by marking one link with a piece of tape, then counting every drive link as the chain passes through your hands until you return to the tape. This number—72 in your case—must be matched exactly.

Common Compatibility Mistakes to Avoid

Understanding these frequent errors will help you avoid wasting money on the wrong chain or potentially damaging your equipment.

Mistake 1: Assuming Bar Length Determines Everything

Many buyers assume that any 72-link chain will fit any 20-inch bar. This is incorrect because pitch, gauge, and mount also affect compatibility. A 72-link chain designed for a 0.325-inch pitch bar will not fit a 3/8-inch pitch bar of the same length, even though the link count matches.

Mistake 2: Ignoring the Gauge

The bar gauge must match exactly. A 0.050-inch gauge chain on a 0.058-inch gauge bar will be dangerously loose. Conversely, forcing a 0.058-inch chain into a narrower groove will cause binding and excessive wear on the bar rails.

Mistake 3: Mixing Pitch Types

Some users try to use a 0.325-inch pitch chain on a 3/8-inch pitch system because the chains look similar. The different tooth spacing means the chain will not engage properly with the sprocket and guide bar, creating a serious safety hazard and poor cutting performance.

Mistake 4: Overlooking Bar Mount Differences

The same manufacturer may offer multiple bar mount options for the same bar length. An interchangeable bar mount may use a different link count than a mounted bar from the same manufacturer, even with identical pitch and gauge specifications.

Mistake 5: Buying Based on Other People’s Recommendations

While knowing that certain saw models commonly use 72 links on a 20-inch bar is helpful, your specific saw and bar combination may differ. Always verify against your owner’s manual or the physical specifications of your current chain rather than assuming a recommendation from a friend or online forum applies to your exact situation.

Frequently Asked Questions

Can a 72-link chain fit all 20-inch bars? No. The link count must match the pitch, gauge, and mount requirements of your specific bar. A 72-link chain for a 3/8-inch pitch, 0.050-inch gauge bar will not fit a bar requiring a different configuration.

What happens if I use the wrong pitch chain? Using a chain with the wrong pitch will prevent proper engagement with the sprocket and guide bar. This can cause the chain to skip, bind, or come off the bar entirely, creating a serious safety hazard.

Why does my 20-inch bar use 70 links instead of 72? Different bar mounts and gauge specifications affect how many links fit around a given bar length. A 20-inch bar with a narrower gauge or different mount may require fewer links to achieve the same cutting length.

Is it safe to use a chain with slightly different specifications? No. Even small mismatches in gauge or pitch can cause safety issues and equipment damage. All specifications must match exactly for safe and effective operation.

Where can I find my exact chain specifications? Check your owner’s manual or look for the stamped specifications on the side of your current chain. If these are unavailable, contact the saw manufacturer with your model number.

Summary

Chainsaws that commonly take a 72-link chain on a 20-inch bar are typically medium-duty models in the 50 to 60cc class, often from Stihl, Husqvarna, and Echo. These saws typically use 3/8-inch pitch chains with 0.050-inch gauge, but the exact link count depends on the specific bar mount and configuration.

Before purchasing a replacement chain, verify the pitch, gauge, drive link count, and bar mount match your specific saw and bar combination. Check your owner’s manual or the specifications stamped on your current chain. Never assume that a chain fitting a friend’s saw with similar specifications will fit yours—small differences in any of these four factors can make a chain incompatible.

When in doubt, consult your saw’s owner’s manual or contact the manufacturer directly with your model number. Taking a few minutes to verify specifications can prevent injury, equipment damage, and the cost of returning an incompatible chain.