Bar length is one of the most misunderstood specs on a chainsaw. Longer doesn’t always mean better—in fact, a bar that’s too long for your saw’s power will slow you down, burn fuel, and wear out your engine. Here’s how to choose the right bar length for your job and your saw.
Bar Length by Task and Engine Size
Different jobs need different bars. And different saws handle different bars. Use this table to find the right match:
| Bar Length | Best For | Engine Size | Common Models |
|---|---|---|---|
| 8–10 inch | Pruning, light trimming, branches up to 2–3 inches thick. Residential garden work. | Under 30cc / Battery (up to 20V) | Makita DUC254, Milwaukee 3004-20, Ryobi OCS1830 |
| 12 inch | Light domestic use, small logs, general garden maintenance. Firewood prep (small rounds). | 30–35cc / 20V battery | DeWalt DCM565, Stihl MSA 120, Makita DUC302 |
| 14 inch | General domestic work, small to medium logs, firewood (most common home size). | 35–40cc / 36V battery | Makita DUC353, Husqvarna 120i, DeWalt DCMCS575 |
| 16 inch | All-round workhorse for most jobs. Felling small trees, firewood, medium logs. Semi-pro domestic. | 40–50cc / 60V battery | Stihl MS170, DeWalt DCMCS575, Milwaukee 2727-20, Makita DUC405 |
| 18 inch | Semi-professional. Larger trees, consistent firewood production, larger logs. | 50–60cc | Husqvarna 445, Stihl MS250, Makita EA3200 |
| 20 inch | Professional felling, large timber, sustained cutting in commercial work. | 60–70cc | Husqvarna 455 Rancher, Stihl MS362, Makita EA4300 |
| 24 inch+ | Milling, large timber felling, professional arboriculture, heavy-duty logging. | 70cc+ | Stihl MS660, Husqvarna 576XP, professional-grade saws only |
The key principle: match bar length to your saw’s power. A 16-inch bar on a 30cc saw will boil the engine. A 10-inch bar on a 60cc saw is overkill and wastes fuel. Find the middle ground for your saw’s displacement.
Why Bar Length Matters
Your bar length determines:
- Maximum cutting depth: You can only cut logs as thick as your bar is long. A 14-inch bar handles logs up to 14 inches thick.
- Engine load: Longer bars require more power. If your bar is too long for your engine, the motor has to work harder, burns more fuel, and wears faster.
- Control and safety: Shorter bars are lighter and easier to handle, especially overhead. Longer bars offer reach but are heavier and harder to control.
- Fuel efficiency: A properly-sized bar maximises cutting speed and fuel economy. An oversized bar drags the engine down.
- Comfort: For all-day work, bar length affects arm fatigue. A 16-inch bar on a 50cc saw all day is better than struggling with an 18-inch bar on a 35cc saw.
Battery Chainsaw Bar Lengths
Cordless chainsaws (battery-powered) typically run shorter bars than equivalent petrol saws. This is because battery motors have lower torque than petrol engines of the same physical size.
Typical battery chainsaw sizes:
- 20V battery saws: 10–12 inch bars. Light domestic use only.
- 36V battery saws: 12–14 inch bars. General domestic and light semi-pro work.
- 60V battery saws: 14–16 inch bars. Professional-grade performance, all-day cutting.
- 80V+ battery saws: 16–18 inch bars. Premium professional cordless saws.
If you’re comparing a battery saw to a petrol saw, expect the battery saw to have a 1–2 inch shorter bar but similar cutting speed due to modern motor efficiency.
Can You Put a Different Size Bar on Your Chainsaw?
Yes, but within limits. Your chainsaw’s bar mount and sprocket are designed for a specific bar length and pitch. You can usually go up or down one size, but larger changes risk problems.
Going shorter: If you fit a 14-inch bar to a saw that came with a 16-inch bar, it will work fine. The engine will actually perform better because it’s less loaded.
Going longer: Fitting an 18-inch bar to a saw designed for 16 inches is possible on some models, but you risk:
- Stalling the engine under load (it’s working too hard)
- Premature engine wear
- Losing cutting speed
- Poor chain tensioning (longer bars can have slack in the chain at idle)
Check your manual or contact the manufacturer to see what bar sizes are approved for your model. Going more than 2 inches beyond the original spec is not recommended.
Understanding Bar Mount Types
Different manufacturers use different bar mounting systems. This means bars from one brand won’t always fit another brand’s saw, even if the size and pitch match.
Common mount types:
- Standard mount: The most common type. Most aftermarket bars fit here. Used by Husqvarna, Stihl, many generic brands.
- Proprietary spline mounts: Some Stihl models use a unique spline system that locks the bar in place. Only Stihl bars fit.
- Side-mount: Older chainsaws. Less common now, but bars are still available.
When buying a replacement bar, always verify it’s compatible with your specific saw model. Check the manual or ask the dealer.
Matching Bar to Chain: The Drive Link Connection
Here’s the critical part: when you change bar length, you must also change your chain.
Chains are measured by drive link count (the number of teeth). A 14-inch bar typically needs 50–52 drive links. A 16-inch bar needs 55–57. A 12-inch bar needs 40–43.
Why? The drive links must fill the groove all the way around the bar. Too few links and the chain rattles and falls off. Too many and the chain jams or snaps.
So if you’re upgrading from a 14-inch to a 16-inch bar, you need to:
- Fit the new bar to your saw (if compatible).
- Buy a new chain with the correct pitch and gauge for your new bar’s drive link count.
- Adjust chain tension after installation.
This is why ordering the exact bar size first is important—it determines which chain you need.
Choosing the Right Bar: Decision Tree
What will you use the saw for?
- Light pruning and trimming: 10–12 inch bar. Even a battery saw works here.
- General garden work and small firewood: 14 inch bar. This is the sweet spot for home use.
- Regular firewood production or felling small trees: 16 inch bar. Worth the investment if you use it weekly.
- Professional or semi-professional work: 18–20 inch bar. Your saw’s displacement and your budget decide between these.
- Heavy-duty milling or large timber: 22–24 inch bar on a 60cc+ engine. Professional equipment only.
If you’re unsure, start with a 14–16 inch bar. This size handles 95% of domestic chainsaw jobs without overworking your engine.
Watch: Video Guide
Frequently Asked Questions
What’s the longest bar I can fit on my chainsaw?
Check your user manual. Most manufacturers list approved bar sizes for each model. As a rough rule, you can usually add 2 inches to the factory bar size, but not more. Going beyond that risks engine damage and poor cutting performance.
Will a 16-inch bar fit on a 40cc saw?
It might fit physically, but it won’t perform well. A 40cc saw is designed for a 12–14 inch bar. A 16-inch bar will stall the engine and slow down your cutting. Stick to bars within your engine’s recommended range.
Is a longer bar always more expensive?
Generally, yes. A longer bar requires a longer chain, which means more material and more money. A 14-inch bar might cost £20–30, while an 18-inch bar could be £40–60. Factor this in when choosing your bar length.
Can I use a 3/8-inch pitch chain on a .325-inch bar?
No. Pitch is hardwired into your bar’s sprocket. A 3/8-inch chain on a .325-inch bar will slip, jam, or break. Always match pitch exactly.
Do battery chainsaws have shorter bar ranges than petrol saws?
Yes. Battery motors generate lower torque, so they work best with 12–16 inch bars. High-end 60V+ battery saws can handle 16–18 inches, but consumer 20V saws are limited to 10–12 inches.
What happens if my chain is too loose on the bar?
The chain will rattle, slip off during cutting, and wear the bar. If this happens, your drive link count is wrong. The chain is either too short (too few drive links) or the bar is too long for the chain. Replace the chain with the correct drive link count.
Should I buy a spare bar for my chainsaw?
If you use your saw regularly (more than weekly), yes. Having a second bar allows you to rotate between them while one is being sharpened or repaired. This saves downtime during busy cutting season.
Can I mix brands? (e.g., a Makita bar on a DeWalt saw?)
Not usually. Bar mounts are specific to each brand and model. A Makita bar won’t fit a DeWalt mount. Always use bars designed for your exact saw model. Generic aftermarket bars may work if they’re sold as compatible with your model.
