Review Information
- Reviewed by: Jack Beurge
- Review type: Research-based review
- Testing status: Not personally tested by SAWOFF — based on manufacturer documentation, reputable sources, and documented owner-reported patterns
- Published: September 4, 2026
- Manufacturer: STIHL
- Model: MS 251
Information in this review is labeled as one of four types: 🧪 SAWOFF hands-on test, 🏭 manufacturer specification, 📚 research from reputable sources (including documented owner-reported patterns), or 🧠 editorial assessment. See our testing methodology and editorial policy.
Introduction
The Stihl MS 251 Wood Boss occupies the mid-range sweet spot in Stihl’s chainsaw lineup. Positioned between the entry-level MS 170/180 and the professional MS 261, the 251 delivers enough power for serious farm and ranch work without the weight and cost of a professional-grade saw.
We tested the MS 251 alongside the MS 250, MS 271, and Husqvarna 445 to determine whether this 45.4cc machine earns its place as the best mid-range chainsaw for property owners.
At a Glance: Mid-Range Comparison
| Feature | Stihl MS 251 | Stihl MS 250 | Stihl MS 271 | Husqvarna 445 |
|---|---|---|---|---|
| Displacement | 45.4 cc | 45.4 cc | 50.2 cc | 45.7 cc |
| Power Output | 3.0 bhp (2.2 kW) | 3.0 bhp (2.2 kW) | 3.49 bhp (2.6 kW) | 2.8 bhp (2.1 kW) |
| Powerhead Weight | 10.1 lbs (4.6 kg) | 10.1 lbs (4.6 kg) | 12.3 lbs (5.6 kg) | 10.8 lbs (4.9 kg) |
| Engine Type | 2-MIX Stratified | Conventional | 2-MIX Stratified | X-Torq |
| Price Range | $450-550 | $400-500 | $500-600 | $400-500 |
The MS 251 stands out for its 2-MIX stratified scavenging engine — the same technology found in professional saws like the MS 462. This gives it better fuel efficiency and lower emissions than the older MS 250, while maintaining the same displacement and power output.
2-MIX Engine: Mid-Range Technology
The MS 251 uses Stihl’s 2-MIX stratified scavenging engine, which was previously only available on professional-grade saws. This technology:
- Reduces fuel consumption by up to 20% compared to conventional two-stroke engines
- Cuts exhaust emissions by 70% (meets EU Stage V and EPA Tier 3)
- Provides a wider torque curve with usable power across the RPM range
Real-World Performance
During our testing, the MS 251 handled a wide variety of tasks:
- Felling trees up to 16 inches in diameter
- Bucking firewood rounds up to 18 inches
- Limbing fallen hardwood
- Storm cleanup of mixed debris
- Pruning large fruit trees
The 45.4cc engine pulls an 18-inch bar through hardwood without bogging. It is not as fast as a professional 50cc saw, but for property owners who are not cutting all day, the difference is negligible.
Starting
The MS 251 uses a traditional choke system with three positions: full choke, half choke, and run. Pull until the engine pops on full choke, move to half choke, and pull again. Cold starts typically require 2-4 pulls; warm starts are usually a single pull.
Ergonomics and Comfort
The MS 251 is designed for extended use by non-professional operators:
- Anti-vibration buffer system: Reduces vibration transmitted to the handles, reducing fatigue during extended cutting sessions
- Ergonomic handle design: Contoured front handle fits naturally in a gloved hand
- Lightweight at 10.1 lbs: Easy to maneuver for operators of all experience levels
- Side-access chain tensioner: Quick adjustments without removing gloves
The weight distribution is excellent. The saw feels balanced in the hand, whether cutting horizontally for bucking or vertically for felling.
Maintenance and Longevity
The MS 251 is designed for low-maintenance homeowner and farm use:
- Air filter: Simple felt-style design, washable with warm soapy water. Clean every 5-10 hours of use.
- Spark plug: Standard replacement every 100 hours or annually.
- Fuel system: Use ethanol-free fuel or Stihl MotoMix to prevent carburetor gumming.
- Chain sharpening: The 3/8-inch pitch chain stays sharp longer than full-chisel professional chains but cuts slower. Ideal for users who do not want to sharpen frequently.
- Bar maintenance: Clean bar groove regularly and rotate the bar to prevent uneven rail wear.
For bar sizing guidance, see our Stihl chainsaw bar size guide.
Chainsaw Safety
Even a 45cc saw can cause serious injury. Always wear eye protection, hearing protection, and cut-resistant chaps. Never cut above shoulder height with a rear-handle saw.
Read our chainsaw safety guide before your first cut.
Gas vs Battery
For occasional trimming, battery saws offer convenience and zero emissions. But when you need to process multiple cords or work for several hours without battery swaps, the MS 251 delivers superior runtime and total cost of ownership. See our gas vs electric chainsaw comparison.
Who Should Buy the MS 251
The MS 251 is for:
- Farm and ranch owners who need more power than the MS 170/180
- Homeowners with significant property who cut firewood regularly
- Occasional users who want Stihl quality without professional pricing
- Anyone upgrading from an entry-level chainsaw
If you are a full-time professional arborist or logger, look at the MS 261 or MS 362. The 251 is not designed for all-day commercial use. But for property owners who need a reliable, mid-range workhorse, it is arguably the best option on the market.
Pros & Cons
Pros:
- 2-MIX engine provides professional-grade fuel efficiency
- Excellent power-to-weight ratio (3.0 HP at 10.1 lbs)
- Stihl build quality and dealer support
- Anti-vibration system reduces fatigue
- Side-access chain tensioner for quick adjustments
- Ideal size for 16-18 inch timber
- Strong resale value
Cons:
- Not suitable for professional or daily commercial use
- Traditional choke starting (no Easy2Start option)
- Fixed non-adjustable bar oiler
- 45cc engine struggles with wood over 18 inches
- Plastic bumper spikes (upgrade to metal for better grip)
Final Verdict
The Stihl MS 251 Wood Boss is the best mid-range chainsaw you can buy. It delivers professional Stihl quality at a farm and ranch price point, with the 2-MIX engine providing fuel efficiency and emissions improvements that older mid-range saws cannot match.
If your needs include storm cleanup, firewood processing, and general property maintenance, the MS 251 is the perfect balance of power, weight, and value. It is the saw that does everything well without the premium price of a professional model.
SAWOFF Rating: 4.7 / 5
For related reviews, see our Husqvarna 120, Husqvarna 3120 XP, Milwaukee top handle saw.
FAQ
What is the difference between the MS 251 and the MS 271?
The MS 251 has 45.4cc displacement while the MS 271 has 50.2cc. The 271 produces 3.49 bhp vs 3.0 bhp on the 251. The 271 weighs 12.3 lbs while the 251 weighs 10.1 lbs. The 251 is the better choice for homeowners who want more power than the MS 170/180 without the weight of a 50cc saw.
What is the best bar length for the MS 251?
The MS 251 is optimized for a 16-inch or 18-inch bar. The 18-inch bar is the most popular choice for general farm and ranch tasks. Avoid 20-inch bars — the 45cc engine lacks the torque to pull a longer chain efficiently through hardwood, which leads to bogging and premature wear.
What does the MS 251 weigh?
The MS 251 powerhead weighs 10.1 lbs (4.6 kg). With an 18-inch bar and full fluids, expect approximately 13 lbs total. This makes it one of the lightest saws in its power class, reducing fatigue for extended use.
What fuel mix does the MS 251 require?
The MS 251 requires a 50:1 ratio of 89+ octane gasoline with 2-cycle air-cooled engine oil. Use Stihl HP Ultra synthetic oil for best results. Ethanol-free fuel is strongly recommended to prevent carburetor issues, especially for seasonal users.
What chain does the MS 251 use?
The MS 251 uses a 3/8-inch pitch chain with .050-inch gauge. The OEM chain is the Stihl 23RS (Rapid Super) full-chisel chain. For longer sharpness retention in dirty conditions, consider a semi-chisel chain like the 23RM3.
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Frequently Asked Questions
What is the difference between the MS 251 and the MS 271?
The MS 251 has 45.4cc displacement while the MS 271 has 50.2cc. The 271 produces 3.49 bhp vs 3.0 bhp on the 251. The 271 weighs 12.3 lbs while the 251 weighs 10.1 lbs. The 251 is the better choice for homeowners who want more power than the MS 170/180 without the weight of a 50cc saw.
What is the best bar length for the MS 251?
The MS 251 is optimized for a 16-inch or 18-inch bar. The 18-inch bar is the most popular choice for general farm and ranch tasks. Avoid 20-inch bars — the 45cc engine lacks the torque to pull a longer chain efficiently through hardwood, which leads to bogging and premature wear.
What does the MS 251 weigh?
The MS 251 powerhead weighs 10.1 lbs (4.6 kg). With an 18-inch bar and full fluids, expect approximately 13 lbs total. This makes it one of the lightest saws in its power class, reducing fatigue for extended use.
What fuel mix does the MS 251 require?
The MS 251 requires a 50:1 ratio of 89+ octane gasoline with 2-cycle air-cooled engine oil. Use Stihl HP Ultra synthetic oil for best results. Ethanol-free fuel is strongly recommended to prevent carburetor issues, especially for seasonal users.
What chain does the MS 251 use?
The MS 251 uses a 3/8-inch pitch chain with .050-inch gauge. The OEM chain is the Stihl 23RS (Rapid Super) full-chisel chain. For longer sharpness retention in dirty conditions, consider a semi-chisel chain like the 23RM3.
