How do I measure my chainsaw bar?

Measuring the bar of your chainsaw is an important step in maintaining your equipment and ensuring optimal performance. The length and width of the bar determines the size of wood it can cut and the power required to operate it efficiently. With a few simple steps, you can accurately measure your chainsaw bar to know the correct replacement size when the time comes.

What is a chainsaw bar?

The bar of a chainsaw is the long metal arm that supports and guides the saw chain. It provides the structure that enables the chain to cut efficiently through wood. Most bars are made of high-strength steel and range in length from 10 inches for small electric saws to over 3 feet for large gas-powered models. The bar mounts to the body of the saw via bolts and includes a groove along its outer edge where the cutting chain rests and travels around the bar. As the chain rotates around the bar, the cutting teeth slice into the wood to make the cut.

Why measure the bar?

There are a few key reasons you’ll want to measure your chainsaw bar:

• To determine the correct replacement size when the bar needs to be changed out due to wear and tear
• To match the power of the chainsaw to an appropriate bar length
• To understand the maximum cutting capacity of your saw
• To select the right length of replacement saw chain

Having the precise measurement allows you to choose the right bar and chain combinations to keep your chainsaw operating safely and efficiently.

What you’ll need

Measuring your chainsaw bar is a quick and easy process requiring minimal tools:

• Chainsaw (turned off and cooled down)
• Tape measure or folding ruler
• Cloth or rag
• Notepad and pencil (optional)

Make sure the saw is turned off and has cooled completely before handling it. It’s also a good idea to disconnect the spark plug wire. For accuracy, use a cloth or rag to wipe any dirt, sawdust, oil, or debris from the bar before taking measurements.

Measuring the length

To measure the length of the bar:

1. Lay the chainsaw on a flat, stable surface with the bar facing upward.
2. Locate the bolts where the bar attaches to the saw body. These indicate the mounting points for the bar.
3. Using your tape measure or ruler, measure the distance between the mounting bolt centers on each end of the bar.
4. Round your measurement to the nearest whole inch or half-inch.
5. Record the length for reference.

This gives you the overall cutting length of the existing bar. Most bars are measured by the inch and range in length between 10″ on smaller saws to over 3 feet on high-powered gas models. Know the length when looking for a replacement.

Measuring bar thickness

In addition to length, you’ll also want to measure bar thickness or gauge. This determines the groove size and how thick the bar steel is. Most common gauges are:

• .050 inches
• .058 inches
• .063 inches

To find the gauge:

1. Locate the gauge stamping usually found along the top edge of the bar.
2. If no stamping is present, use calipers to measure the groove width.
3. Compare to a bar gauge chart to determine thickness.

Match this measurement when purchasing replacement bars so the groove properly fits the chain.

Tips for accurate measurement

Follow these tips for getting precise bar measurements:

• Clean the bar first – Remove any debris that could affect reading the tape measure or ruler.
• Lay bar flat – Place on a level surface and don’t eyeball the measurement.
• Avoid bending – Applying pressure can flex the bar and alter accuracy.
• Measure between mounting holes – This gives overall cutting length, not just the steel.
• Round to nearest 1/2″ – This accounts for minor variability in manufacturing.
• Note thickness stamp – Helps match groove size for chain replacement.
• Use quality tools – A quality folding ruler or tape measure improves precision.
• Confirm gauge with calipers – If stamping isn’t visible, this verifies thickness.

Taking these steps when measuring will give you the information needed to select the right replacement bar. It also provides the data to properly balance bar length with chainsaw power and capabilities.

How to read the measurements

Once you’ve measured, you’ll want to understand the meaning of the length and gauge figures. This helps determine the correct replacement and saw capabilities.

Length

The length measurement indicates the cutting capacity of the chainsaw based on the existing bar. Longer bars allow deeper cuts into wood but require more engine power. For example:

• 10″ to 16″ bars – Best for light pruning and small limbs
• 16″ to 20″ bars – All-around residential cutting tasks
• 20″ to 28″ bars – Professional cutting and felling smaller trees
• 30″ to 36″ bars – Large tree felling and milling operations

Match bar length to chainsaw engine displacement. Too long of a bar without enough power causes bogging and poor performance. Refer to manufacturer guidelines for ideal bar lengths based oncc or horsepower.

Gauge

The gauge or thickness relates to bar groove width. This must match the drive links on the chain. Common gauges include:

• .050″ – Light duty consumer saws
• .058″ – General purpose and mid-size professional saws
• .063″ – Large gas-powered chainsaws

Using a mismatch chain and bar causes premature wear from a loose fit. The chain can also come off the bar more easily. Always match gauge size for optimal cutting and safety.

How to change a chainsaw bar

Once you know the correct replacement bar size, here are the basic steps to swap it out:

1. Disconnect spark plug wire.
2. Remove bar nuts and take off old bar.
3. Clean sawdust and debris from bar slot.
4. Install new bar in slot properly aligned.
5. Replace nuts and tighten fingertight plus 1/4 turn.
6. Check for free movement of chain around bar.
7. Adjust chain tension for proper tightness.
8. Reconnect spark plug wire when finished.

Consult your operator’s manual for detailed bar installation instructions. Proper alignment and tension are critical for safe operation and optimal sawing performance.

Frequently asked questions

Why does my bar have two length measurements?

Some bars are stamped with two numbers, such as 18/20. The first number indicates the actual cutting length in inches. The second represents the overall “nose-to-tail” length end to end.

What does .325 mean on my bar?

.325 refers to the pitch or spacing between the drive links on the matching chainsaw chain. The chain pitch must align with the sprocket teeth and bar groove.

Can I mount a 20-inch bar on a 45cc saw?

It’s not recommended. A 20-inch bar requires 50cc or larger displacement for optimal power. Check manufacturer guidelines for proper bar sizing.

Is there a standard chain length?

Yes, chains are typically sized based on the number of drive links. Consult a chain length chart or your operator’s manual for guidelines on your model.

Should I buy the bar and chain together?

Yes, purchasing them as a set ensures proper sizing between bar groove, chain gauge, and chain length.

Conclusion

Learning how to properly measure your chainsaw bar is the first step to replacing it when worn or upgrading to maximize your saw’s capabilities. Take accurate length and gauge measurements, then match to an appropriate replacement bar based on your saw’s engine size. With the right bar and chain combination, you can improve cutting performance and extend the life of your chainsaw.