18 in. Bar

A powerful and fuel-efficient chainsaw that’s comfortable to use.

The STIHL MS 251 WOOD BOSS® Chainsaw is powerful, fuel-efficient and easy to use. Ergonomically designed to bring you maximum comfort during use, this tool produces 50 percent less emissions (as compared to previous models) for a smaller impact on the environment. The MS 251 WOOD BOSS® packs features like a Master Control Lever™ and easy-to-refill fuel and oil tanks, so you can worry less about st...Read More
Print Spec Sheets
MS 251 WOOD BOSS® Specifications
DISPLACEMENT 45.6 cc (2.78 cu. in.)
ENGINE POWER 2.2 kW (3.0 bhp)
POWERHEAD WEIGHT 4.9 kg (10.8 lbs.)
FUEL CAPACITY 390 cc (13.2 oz.)
CHAIN OIL CAPACITY 198 cc (6.7 oz.)
GUIDE BAR LENGTHS (Recommended ranges) 40 to 45 cm (16" to 18")
STIHL recommends #3634 (26 RM3 68) OILOMATIC® saw chain and 18" 3005 008 4717 STIHL ROLLOMATIC® E guide bar combination. The actual listed guide bar length can vary from the effective cutting length based on which powerhead it is installed on.
Model Features
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    Built in the USA
    Indicates products that are built in the United States from domestic and foreign parts and components.

    More Information

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    Reduced-Emission Engine Technology - Caring for Nature
    The STIHL Inc. “Caring for Nature” seal identifies its powered products that are more environmentally conscious, producing zero or low exhaust emissions. STIHL Inc. defines “low exhaust emissions” as being cleaner than EPA and/or CARB exhaust emission standards.

    More Information

  • Zoom
    Toolless fuel and oil caps with retainers
    Simply lift the lever and twist the caps to remove or tighten. There‘s no need to use a tool to tighten or loosen.
  • Zoom
    Master Control Lever™
    The Master Control Lever™ is an easy to use single lever, operating the choke, starting throttle lock and on-off switch. The operator must pull the throttle trigger before moving the Master Control Lever™ to the choke position.
Standard Features
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    Common Features for Chainsaws
    View the features common to many STIHL chainsaws.

Important Information
* The actual listed guide bar length can vary from the effective cutting length based on which powerhead it is installed on.
WARNING! Improper use of any power tool may cause serious or fatal injury. Read, understand and follow carefully the operating and safety instructions in your instruction manual before using such products.

STIHL products sold through U.S. STIHL Dealers are for distribution in the United States only.
Click to view the STIHL Limited Warranty Time Periods
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    •2.6 oz. bottle makes 1 gallon mix

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    Bar and Chain Oil
    STIHL Bar and Chain oil is formulated to adhere to the bar and chain, and to reduce wear. Special agents in the oil formulation help keep sap and pitch from clinging to the bar and chain.

    Available in quart and gallon bottles, 5 gallon pails and 55 gallon drums, in both summer and winter weights.

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    Complete Filing Kits
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    Chain Pitch File Diameter File Guide
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    Sharpening Kit
    Part Number
    in. mm in. mm Part Number
    3/8 PMN 9.32 5/32 4.0 0811 411 8073

    5605 750 4327

    5605 007 1026

    3/8 PM
    5/32 4.0 0811 411 8091

    5605 750 4327

    5605 007 1027

    0.325 8.25 3/16 4.8 0811 412 8088

    5605 750 4328

    5605 007 1028

    3/8 9.32 13/64 5.2 0814 243 3384 5605 750 4329

    5605 007 1029

    0.404 10.26 7/32 5.5 0811 412 8108 5605 750 4330

    5605 007 1030

For Your Safety
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    The lightweight STIHL Woodcutter Helmet System is an excellent choice for budget-conscious non-professional users with chainsaws and pole pruners. Designed for comfort, the vented shell provides cooling air during use, and the 6-point mount suspension provides comfortable support. The STIHL Woodcutter Helmet System is Class G certified and includes NRR 22 hearing protection.
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    Durable and hardworking, STIHL Pro Mark™ Dynamic Gloves deliver professional-grade hand protection. The palm and inner fingers are made of full grain tanned leather, so you can work with comfort without sacrificing a firm hold. Featuring multiple layers of cut-retardant materials – Avertic Pro and Dyneema fabrics by Engtex® – these gloves will help deliver protection without compromising the dexterity you need while operating a chainsaw. Accented with an orange rip-stop nylon backing, these dynamic gloves offer style and protection. Water repellant, breathable and featuring a Velcro wrist closure, STIHL Pro Mark™ Dynamic Gloves are as ready for the woods as you.
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Are You Ready for a STIHL?

MS 251 WOOD BOSS® is rated 4.3 out of 5 by 368.
Rated 5 out of 5 by from Easy to use The MS251 is a great machine.I feel very comfortable with it. I have the wood boss with an 18 inch chain. It just kept cutting with no jamming or kicking. I was amazed how it went through a 32 inch diameter stump in no time at all.The cut around the stump was fairly even.I went through 2 Pine stumps about 32 inches diameter,2 Locust stumps about 16 inches and a 24 inch Gum tree stump with the same blade and it still kept going with no problem.The last Stump was a 30 inch diameter Pine that was still a bit damp and the chain started to dull.Not a bad performance for an impressive first time with this saw. I recommend it.
Date published: 2018-08-09
Rated 5 out of 5 by from This is a handy compact chainsaw Used the saw extensively for two weeks after the purchase and it has performed flawlessly. Starts easy, is light enough for long hours of limbing trees and has enough power to fall trees up to 24" (mine has an 18" bar). I was even able to cut rounds out of larger tree trunks (+/- 30").The chain adjustment was simple, as was re-fueling and oiling with bar oil.
Date published: 2018-08-08
Rated 1 out of 5 by from Hard to start Hard (ie won’t start). Used it once. Was hard to start out of the box. Wouldn’t run at idle. Adjusted carb as directed to keep it running at idle, but still wouldn’t idle. Now, 4 weeks later, it won’t start period.
Date published: 2018-08-06
Rated 5 out of 5 by from Better than expected! So much better than I could have hoped for. Power for days, and very efficient, both in terms of fuel and in making short work of any project.
Date published: 2018-08-05
Rated 5 out of 5 by from Awesome machine Highly recommend this saw with a 16 inch bar and chain works great on any type of trees....has enough power to do any job around the house also use it for tree stand work as well. Buy one u can’t go wrong.
Date published: 2018-08-05
Rated 4 out of 5 by from Good chainsaw Starts first try every time. Great quality. Easy to operate.
Date published: 2018-07-31
Rated 5 out of 5 by from Amazing saw for the price Got this saw when a buddy of mine had 4 trees blow down in his yard. Got to his house with a husquvarna and that was a joke. Went to the Stihl dealer told the salesman what I was doing and he said this saw here is the one for you and man was he right. Im only 22 years old but this saw is light and the vibration control system it has is amazing. My buddies dad has this same saw and his is 5 years old and you can tell a huge difference in the vibration in the saw after running it for 30 mins. My buddy and I cut those trees up in 2 evenings after work and loaded up a 16 ft long 6 ft wide trailer with wood 4 times. The saw performed flawlessly. The bad thing is it burns fuel like crazy. I wish Stihl had put a bigger tank on this saw. Also if you plan on cutting up more than one mature hardwood tree definitely buy more chains it will make life easier in the long run. I could go on about this saw all day. Overall just an amazing saw and it cannot be beat by any other brand.
Date published: 2018-07-29
Rated 5 out of 5 by from All around great saw Gave my bro my 30 y.o. Av028 after he tuned it up. Stihl a darn good saw after all these years. Bought an MS 251 Wood Boss for myself. I expect another 30!
Date published: 2018-07-23
Rated 5 out of 5 by from Stihl good after 3 years Had this saw for 3 years now. Use it probably 6-10 times a year. I only use non-ethanol 89 or higher. Always use the right amount of oil and dump out old gas. Usually starts with 3 or 4 pulls for me.I have had it bog down a few times on me, but I am not cutting down tree after tree so I don't need the power of the big heavy saws. For it's size and weight I would say it's still pretty powerful. No real complaints. The bar will need to be cleaned every so often as well. It will clog up with shavings if you ever use a dull chain. That will keep the oiler from working and will get your bar hot. Keep a sharp chain to make big chips instead of saw dust and you will be ok. I was a beginner when buying this one. Had only used a chain saw a dozen or so times. So the saw has been easy to maintain and clean. Not sure what all the start issues are for everyone else.
Date published: 2018-07-22
Rated 5 out of 5 by from Best all-round performer for a home-guy I have used & still have, a range of STIHL chainsaws, which I have collected over the years. This particular baby, gives me the most satisfaction for general all-round home & forest applications. I use from 14"-18" bars & find it has sufficient power across the range.
Date published: 2018-07-20
Rated 1 out of 5 by from Hard to rate because it is hard to start I purchased a still ms251 April 24 2018 , this is the most difficult saw to start l have ever owned ! Twice in that time l have not been able to start the saw at all . I am inclined to sell this saw to someone very cheaply and purchase another brand !
Date published: 2018-07-18
Rated 5 out of 5 by from Excellent all around saw Nothing but good things to say after 5 years of ownership. Have trimmed trees to cutting up trees after hurricanes. Never let me down (knock on wood)LISTEN to the salesperson on how to START and MAINTAIN the saw.My MS251 requires me to move the start lever all the way down, pull until it tries to fire up (after 3 pulls - EVERY SINGLE TIME) then move the lever up 1 notch, then its 3 more pulls and it starts every time. Which I might add, is exactly what the dealer told my when I bought it. any deviation from that procedure and you might as well go find something else to do for an hour or so...Side note: I have used the Stihl premix fuel from day one. Its a little pricey but Im not a professional chainsaw user, so i dont mind the extra cost for the piece of mind that it can sit in the saw for months and cause zero damage.
Date published: 2018-07-15
Rated 5 out of 5 by from Great product for my jobs Great saw makes for easy removal of debris. Shopped several brands and glad to choose STIHL
Date published: 2018-07-13
Rated 3 out of 5 by from after a week its getting disappointing I have owned the saw for about 2 weeks now, At first is would start on the second pull. Now is about 10 pulls. Starts like my Stihl weed wacker. :-(
Date published: 2018-07-12
Rated 5 out of 5 by from Funky Start, but worth the effort Recently made a slight upgrade from the MS180 to get a little more power and larger bar/chain. I'm glad I went with the Wood Boss. Lots more saw (watch out for that kickback!), for not a lot more money. Not too heavy, and very comfy to operate. Starting is a little tricky due to all of the springs mounting the powerhead, but once you get passed that, its great. Much larger oil and fuel capacity which is nice, as I constantly had to refuel the 180. A word of advice, go for the MotoMix. Oldschoolers won't endorse it, but it saves a lot of time, mess, and headaches. Need to store it for months on end? No need to drain the fuel and run it dry, since it doesn't break down and gum up your carb! Great saw for the money and I'm happy to have made the upgrade. I really feel like I'm going to be hanging on to this saw for quite a while.
Date published: 2018-07-10
Rated 2 out of 5 by from Had to go back to Stihl only 3 weeks after purchase I purchased this saw less than a month ago Used it a couple of times (about 3-4 hours total) and It would not start. Took it back to store where purchased and they could not get it started either and said that it was something with the ignition and it had to go back for factory repair. I am very disappointed, especially since Stihl came so highly rated by my friends.
Date published: 2018-06-25
Rated 5 out of 5 by from I Love the saw Great saw! Does the job quickly and efficiently I really recommend it really really great saw
Date published: 2018-06-22
Rated 4 out of 5 by from one hot restart issue other than that runs like a dream I have used a lot of hand saws and chainsaws hands down the best gift my wife has given me except for our kids
Date published: 2018-06-15
Rated 4 out of 5 by from Great Saw, but I have had issues starting it. Great Saw, but I have had issues starting it. Once it starts, it has been great.
Date published: 2018-06-14
Rated 5 out of 5 by from Wood Boss I"ve owned other chainsaws, but nothing compares to a stihl. I love it.
Date published: 2018-06-12
Rated 5 out of 5 by from Best Product This is working as we expected. We are maintaining this machine easily
Date published: 2018-06-09
Rated 5 out of 5 by from This is a great saw. Far exceeds expectations. Its an awesome saw........................................................
Date published: 2018-06-04
Rated 2 out of 5 by from No Power. Broke the 2nd day I used it. I am a homeowner so did not need a professional saw, but wanted to replace my roughly 20+ year old Poulan 260 Pro that I bought at Lowes. It had always started easy and cut great, but several parts were wearing out so I decided to run up the road an buy a new saw. The salesman pointed me to the 251 when I told him I wanted an 18" bar. It started easy enough (despite the many reviews that say it does not), and for small limbs, it cuts just fine. Try taking down a 10" diameter tree or cutting a stump at the base and forget it. Binds up and bogs down. To make matters worse, the bolt that holds on the bar unscrewed from the frame when I went to remove the outer nut to change the chain (which dulled after 3 stumps). I will return it next week. As I side note, I got my old Poulan running and buzzed thru about 12 stumps and took another tree down without any hesitancy or having to change the chain. Very disappointed especially for the price (not to mention no case or extra chain).
Date published: 2018-06-02
Rated 5 out of 5 by from The perfect saw for small to medium jobs This saw is a work horse. It's light weight and easy to use.
Date published: 2018-06-02
Rated 5 out of 5 by from This saw replaced my 028. Saw . My Wood Boss has been performing like a champ, Cut a lot of fire wood! Purchased this 2 Year’s ago. Have a larger Stihl saw ,but this Wood Boss is my go to 98% of the time. Great products!
Date published: 2018-05-29
Rated 4 out of 5 by from Excellent option in a smaller saw I owned a Stihl 026 for about 15+ years. It delivered reliable service to maintain trails, remove blowdowns and general utility work on a 325 acre tree farm/hunting property. I replaced it in July 2017 with a MS-271 that I used twice before dislocating a shoulder in an unrelated accident. The 271 became simply too much saw and I researched lighter options that would still get my jobs dome. The MS-251 is a very nice compromise...lighter saw by almost 2 pounds w/18-inch bar vs the 271. The engine has good power if you give it time to do its work..doesn't match the 271 but I am prepared for the trade off. Cuts up to 14 inch spruce with no problems but light enough for limbing & bucking for trail work.
Date published: 2018-05-25
Rated 3 out of 5 by from Continual breakdowns I've gone through three Stihl saws in two weeks. The first two were lighter weight and we’re extremely hard to start. The first one froze up and the pull cord broke. The second one wouldn’t restart after an hour of use. I upgraded to the 251 and it worked great until the chain kept falling off. I took it back to the store and the trained Stihl tech said I was doing something wrong. He showed me how to tighten it (which I'd already done correctly) and then cut a log. The chain fell off. He tightened it again and got the same results. He then took it in for warranty repairs. I just picked it up and I'm hoping I can actually cut some wood. As a side note, the clerk who got the saw for me said she wouldn't start it for me because “it's the hardest saw she's ever tried to start” and didn’t want to risk dislocating anything.
Date published: 2018-05-24
Rated 1 out of 5 by from Really hard to start! I have only had the saw 4 days, it started fine on day 1, took several pulls on day 2, on day 3, when I was running out of time on my "rental" splitter, and had only 2 cuts to make to finish up, it would not start! I followed the Hellebucks, sales persons instructions- (he did say that some customers have had starting issues with Stihl chainsaws- I thought how could a brand new Stihl, with its reputation be harder to start than my previous saws (both Poulan) so I was forwarned. -put on full choke, listen for what he called 'burp" --switch to half choke, pull to start, ---let warm for a few seconds and hit the throttle to disengage choke. Could not start to save my soul! After 45min. of trying, waiting for 10-15 min in between tries, I gave up on the saw, barely muscled the wood into the splitter and paid the extra fee for bringing it back late.The moral of this long-sad story is I would not recommend this saw to anyone, and unless I brought home a defective saw (quality control?) the Stihl reputation does not continue for me.
Date published: 2018-05-23
Rated 5 out of 5 by from Nice saw, runs clean Great saw. I picked up the original MS 250 when they had a deal on them, and that was a nice saw but it got stolen by some loser. I eventually picked up a 251, and to be honest, it runs cleaner and it's noticeable. Fumes probably aren't a big issue for a lot of people, but it was a difference I noticed between the saws. Starts easy, but let her warm up in idle for a while or she'll stall out.
Date published: 2018-05-18
Rated 1 out of 5 by from Hard to start This is my 3rd and probably last Stihl chain saw. On its second use it took 10 minutes to get started. Used it for a while and then shut it off. Half hour later I tried to use it again and would not start. Took a long time and 40-50 pulls to get it started. Worse running chani saw I ever owned. Taking back to dealer to see if they can fix it.
Date published: 2018-05-17
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