How to Measure a Chainsaw Bar and Chain
Measure a chainsaw bar from the front of the saw body, where the bar comes out, to the tip of the farthest cutter, then round up to the nearest even inch. That’s the called length, the size the bar is sold as (for example 16 in). To buy a matching chain you also need three numbers: pitch, gauge and drive link count. They are usually stamped on the bar near the saw body.
Called length vs true length
| Measurement | How to measure | Used for |
|---|---|---|
| Called length | From the saw body to the tip of the farthest cutter, rounded up to an even inch | Buying a bar; the size shown on the box (14, 16, 18, 20 in…) |
| True length | The whole bar, end to end, off the saw | Rarely needed; a few inches longer than the called length |
So a bar that measures 15-1/4 in from the body to the cutter tip is a 16 in bar.
How to measure the bar
- Switch off the saw and, for a gas saw, pull off the spark plug cap; for a battery saw, remove the battery.
- Wear gloves; the chain is sharp even when still.
- Hook a tape measure at the point where the bar leaves the saw body.
- Measure to the farthest cutter at the bar tip.
- Round up to the nearest even inch.
The three chain numbers
| Number | What it is | Common sizes | How to find it |
|---|---|---|---|
| Pitch | Spacing of the chain’s links | 1/4, .325, 3/8 low profile, 3/8, .404 in | Distance across three rivets ÷ 2, or the bar stamp |
| Gauge | Thickness of the drive links, which must fit the bar groove | .043, .050, .058, .063 in | Bar stamp; or slide a gauge tool or drill bit into the bar groove |
| Drive links | The number of links that sit in the bar groove | For example 56, 60, 62, 66, 72 | Count them, marking the first link |
All three must match the bar and the saw’s sprocket. A chain that’s the right length but the wrong pitch or gauge won’t run safely, even if it fits on the bar.
Counting drive links: mark one drive link with a marker, then count every link that points down into the bar groove until you get back to the mark.
Choosing a new bar length
When you replace the bar, you can stay with the same length or change within the range your saw’s maker allows. A bar about 2 in longer than the wood you usually cut is the common rule; 16 vs 18 inch chainsaw compares the two most popular sizes.
After fitting a new bar or chain
- Set the chain tension: it should pull away from the bar slightly by hand but not hang loose underneath.
- Fill the bar oil tank and check that oil reaches the chain; see can you use used motor oil for chainsaw bar oil.
- Recheck the tension after the first few cuts, because a new chain stretches.
Related guides
Frequently asked questions
What is the difference between called length and true length?
Called length is the usable cutting length, measured from the saw body to the tip and rounded to an even inch; it's the size the bar is sold as. True length is the whole bar, including the part inside the saw, and is a few inches longer.
Where is the chain size printed?
Usually on the bar near the saw body: pitch, gauge and often the drive link count. Some chains also have the pitch and gauge stamped on the drive links.
How do I measure chain pitch?
Measure the distance between three consecutive rivets and divide by two. Common pitches are 1/4, .325, 3/8 low profile, 3/8 and .404 in.
Related guides
- Guide
How to Sharpen a Chainsaw: File vs Electric Sharpener
How to sharpen a chainsaw chain with a round file or an electric sharpener: file size by chain pitch, filing angles, depth gauges and when to sharpen.
- Guide
Can You Use Used Motor Oil for Chainsaw Bar Oil?
Why used motor oil makes poor chainsaw bar oil: it lacks tackifier, carries metal and soot, and can void the warranty. Better alternatives listed.
- Guide
16 vs 18 Inch Chainsaw: Which Bar Length Do You Need?
16 vs 18 inch chainsaw bars compared: wood size each cuts, engine size, weight, control and safety, and the simple rule for choosing a bar length.