A chainsaw bar’s length is its effective cutting length — measure from the tip to where the bar enters the saw body, then round up to the nearest even inch.
Ordering the wrong replacement bar is a costly mistake that keeps your saw idle. The trick is knowing that a “16-inch bar” isn’t 16 inches total — it’s the usable cutting portion. Here’s how to measure yours in under two minutes with a tape measure, so the next bar you pick fits and cuts correctly.
Why The Effective Cutting Length Matters
The number printed on a chainsaw bar’s side (like 16″ or 20″) refers to the effective cutting length — the portion of the bar that actually engages the wood. The bar’s total tip-to-tail length is roughly 2–3 inches longer than that number, because the tail contains mounting slots and hardware that sit inside the saw body. Measuring the total length is the most common mistake, and it guarantees you buy the wrong size.
How To Measure Chainsaw Bar Length: The 3-Step Method
You don’t need to remove the bar for this measurement. A standard tape measure is the only tool required.
- Set the saw on a flat surface. A workbench or the ground works — just make sure the saw is stable and the bar is fully exposed. Leave the bar mounted unless the instructions for your specific model call for removal for extra accuracy.
- Lay the tape measure from the tip of the bar. Run the tape straight back along the bar’s center until you reach the point where the bar meets the chainsaw body. Stop there — do not include the saw’s mounting hardware, nuts, or the outer edge of the power head. You want the distance from the tip to the bar-body interface.
- Round up to the nearest even inch. Chainsaw bars are manufactured only in even-inch increments. Standard sizes run 10, 12, 14, 16, 18, 20, 22, 24 inches and beyond.
One visual cue: an 18-inch bar will have a usable cutting length of roughly 18 inches, but its total tip-to-tail length is about 20.5 inches. The mounting slot takes up the difference.
What To Measure For The Chain (Pitch, Gauge, Drive Links)
Matching the bar length alone isn’t enough — the chain must also match three other specs. Here is the breakdown of each dimension and how to measure it.
| Chain Spec | What It Measures | How To Measure |
|---|---|---|
| Pitch | Distance between three consecutive rivets, divided by 2 | Measure 3 rivets center-to-center with a ruler; divide that number by 2. Common values: 3/8″,.325″,.404″. |
| Gauge | Thickness of the drive link (the part that rides in the bar groove) | Use a dial caliper to measure the flat top of a drive link. Standard sizes:.050″,.058″,.063″. |
| Drive Links (DL) | Total count of links that fit inside the bar groove | Count along the chain’s interior; mark the start link so you don’t lose your place. 66 DL +.325 pitch +.058 gauge = 16-inch bar in most cases. |
If your bar’s stamped markings have worn off, counting the drive links is the most reliable fallback method. The pitch and gauge numbers must match exactly between the chain and the bar sprocket nose — mismatched chain specs cause poor cutting and can snap the chain under load.
Where To Find The Bar Length Stamped On The Bar
Most chainsaw bars have the length printed or stamped directly on the tail end — the part hidden inside the saw body. When the saw is off and cool, remove the bar cover and slide the bar partway out. Look for a number followed by a ″ or IN after a model or part code. For example, a bar labeled “Husqvarna H30-18” confirms it is an 18-inch bar. If the stamp is illegible, the three-step measurement method above is your backup.
Our tested picks for the best 18-inch chainsaw bar cover the most popular replacement size for home-use and professional saws, with verified fit specs for each model.
Common Mistakes That Lead To The Wrong Bar
- Measuring total bar length. This is the #1 error. Always measure the effective cutting length from the tip to where the bar meets the saw body, not the very back of the mounting slot.
- Including mounting hardware. Nuts and chain-tension bolts are part of the saw, not the bar. The measurement ends at the bar body itself.
- Skipping the round-up step.
- Assuming a “16-inch bar” is 16 inches total. The total length is always longer than the labeled size. A 16″ bar measures roughly 18.5 inches from tip to tail.
Safety And Compatibility Checks Before You Buy
A bar that fits the mounting pattern is not automatically safe. Every chainsaw model has a certified bar-length range. Installing a bar longer than that range increases the leverage on the engine and clutch, which can cause unsafe kickback or damage the saw’s bearings. Check your owner’s manual or consult the manufacturer’s dealer support if the bar markings are gone. The chain must also match the bar’s sprocket nose and groove — always verify pitch, gauge, and drive-link count together.
Quick-Reference Table: Common Bar Sizes And Their Real Dimensions
| Labeled Size (″) | Effective Cutting Length (″) | Typical Total Length Tip-To-Tail (″) |
|---|---|---|
| 14 | 14 | ~16.5 |
| 16 | 16 | ~18.5 |
| 18 | 18 | ~20.5 |
| 20 | 20 | ~22.5 |
| 22 | 22 | ~24.5 |
| 24 | 24 | ~26.5 |
Use this table as a quick cross-check: if your total tip-to-tail measurement matches the “Typical Total Length” column, you have the right labeled size.
FAQs
Can I measure the bar while it’s still on the saw?
Yes. Leaving the bar mounted is the recommended approach for accuracy. Simply set the saw on a flat surface, lay the tape from the tip to where the bar meets the saw body, and round to the nearest even inch.
What if the bar has no readable numbers?
Use the three-step tape-measure method to find the effective cutting length, then count the chain’s drive links to confirm. Combining the measured length with the drive-link count almost always identifies the correct bar size.
How does bar length affect cutting power?
A longer bar lets you cut through thicker logs in a single pass but puts more strain on the engine. A shorter bar gives more leverage and control. Stick to the bar-length range listed in your saw’s manual to keep the engine running in its safe power band.
Do electric and petrol chainsaws use the same bar measurement?
Yes. The effective-cutting-length method applies to both gas and electric saws with replaceable bars. The only difference is the power head’s certified bar-length range — electric models often top out around 18–20 inches.
Does the chain pitch affect the bar length I need?
No. Pitch, gauge, and drive-link count determine which chain fits the bar, but the bar length is a separate measurement. You match the chain to the bar’s length, not the other way around.
References & Sources
- RGC Construction. “Chainsaw Bar and Chain Sizing Guide.” Covers effective cutting length, pitch, gauge, and drive-link measurement method.
- Husqvarna US Support. “How to measure the chainsaw bar length.” Official manufacturer procedure for petrol chainsaw bar measurement.
- Lowe’s. “Chainsaw Chains and Bars Sizing.” Retailer guide with step-by-step measurement and common-mistake warnings.