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The Stihl MS 251 chain size is a .325-inch pitch chain. On the 18-inch bar Stihl ships today, that’s a .050-inch gauge chain with 68 drive links, Stihl’s 23 RM3 68. Pitch, gauge and link count all have to match your bar, though, and not every MS 251 still wears the bar it came with. So before you order a chain, read the numbers stamped on your bar. It takes ten seconds and saves a return.
I run a Stihl MS 251 C with a 20-inch bar as my everyday saw, with an older Stihl MS 230 as my backup and a Stihl HT 131 pole saw for high limbs. Below is what each one takes, how to read any bar, and which file to sharpen with.
Stihl MS 251 chain size at a glance
What
MS 251 (current factory setup)
Pitch
.325 inch
Gauge
.050 inch (1.3 mm)
Drive links, 18-inch bar
68
Stihl chain
23 RM3 68 (Rapid Micro 3)
Round file
4.8 mm (3/16 inch)
Stihl also says the MS 251 can run 3/8-inch P chain if it has the matching bar and sprocket. If your saw came used, or someone swapped the bar, the chart above may not fit it. The bar is the only thing that tells you for sure.
How to read the numbers on your bar
Look at the flat part of the bar near where it bolts to the saw. Stihl stamps three numbers there.
Pitch is the spacing of the chain links: .325, 3/8 P, 1/4 P and so on.
Gauge is the thickness of the drive links that ride in the bar groove. It may be in millimeters: 1.1 mm is .043 inch, 1.3 mm is .050 inch, and 1.6 mm is .063 inch.
Drive links is how many links ride in the groove. That number, not the bar length, is what you order by.
If the stamp is worn off, take the old chain off, lay it flat, and count the drive links (the pointed links on the bottom). Then measure the groove or ask your dealer to check it. A chain with the wrong gauge will be loose in the groove or won’t seat at all.
Stihl MS 230 chain size
The MS 230 was my firewood saw on our 3-acre place, and it’s my backup now. Stihl’s owner’s manual for the MS 210, MS 230 and MS 250 lists the MS 230 with a 3/8-inch P pitch chain, a .050-inch (1.3 mm) groove, and bars of 12, 14 or 16 inches. The chains it names are Picco Micro Comfort 3 (63 PMC3) and Picco Duro (63 PD3), on a 6-tooth spur sprocket.
The drive-link count depends on your bar length, so read the bar or count the old chain. A 3/8 P chain takes a 4.0 mm (5/32 inch) round file.
Stihl HT 131 pole saw chain
Pole saws don’t share chains with your chainsaw. They run a smaller, narrower chain on a short bar, and the specs published for the HT 131 don’t all agree. Stihl’s current pole pruner lineup no longer lists the HT 131 (newer models such as the HT 135 have taken its place), so many owners are working from an older manual or none at all. Read the numbers on your pole saw bar the same way as above, and order to match them exactly.
Which file to sharpen with
The round file has to match the pitch, or you’ll grind the cutter to the wrong shape. These are the sizes Stihl lists for its 2-in-1 file guide.
Chain pitch
Round file
.325 inch (MS 251)
4.8 mm (3/16 inch)
3/8 inch P (MS 230)
4.0 mm (5/32 inch)
1/4 inch P
3.2 mm (1/8 inch)
A 2-in-1 file guide sharpens the cutters and lowers the depth gauges in the same stroke. For a homeowner who sharpens a few times a season, it’s the easiest way to keep a chain cutting straight.
For a Stihl saw itself, go to a local Stihl dealer. That’s where the warranty is handled, and my two dealers here in East Texas are always helpful and usually have parts in stock. If yours doesn’t have what you need, chains and files for the MS 251 and MS 230 are on Amazon. Match the pitch, gauge and drive-link count exactly, and buy from a listing that names those three numbers.
Buying a new saw instead? Start with our gas chainsaw buying guide, which covers sizing by your trees and why where you buy affects the warranty. If you own a Remington, our Remington RM4620 review lists its chain size too.
Stihl MS 251 chain size FAQ
What size chain does a Stihl MS 251 use?
A .325-inch pitch chain. On Stihl’s current 18-inch bar it’s .050-inch gauge with 68 drive links (Stihl 23 RM3 68). Check the numbers stamped on your bar before ordering, since bars get swapped.
Can I put a 20-inch bar on a Stihl MS 251?
Yes. I run a 20-inch bar on my MS 251 C. Order the chain to match that bar’s own stamped numbers, not the 18-inch chart, and ask your dealer if you’re unsure the bar suits your sprocket.
What file size do I need for a Stihl MS 251?
A 4.8 mm (3/16 inch) round file, the size Stihl lists for .325-inch chain.
What chain does a Stihl MS 230 take?
Stihl’s manual lists 3/8-inch P pitch and a .050-inch groove, with Picco Micro Comfort 3 or Picco Duro chain. Count your drive links or read the bar for the length.
Can I use a non-Stihl chain on my Stihl?
Yes, if the pitch, gauge and drive-link count all match your bar. Those three numbers are what make a chain fit, whatever brand is on the box.
