22" and 24" are the two most-sold disc blade diameters in North America. If you're staring at a worn blade and thinking "close enough, I'll just order the next size up" — don't. The two-inch difference matters more than you'd think. Here's what actually changes when you go from 22 to 24, and how to decide which one your machine takes.
The rule: match the OEM diameter, don't upsize
Every disc harrow is engineered around a specific blade diameter. The gang bearings, frame geometry, hitch height, and hydraulic reach are all calibrated for that size. If your machine came from the factory with 22" blades, running 24" blades will:
- Change the cut depth by ~1" (the extra radius sits deeper in the ground)
- Change the operating angle (bigger blades ride at a shallower angle for the same gang setting)
- Add weight per blade (a 24" is roughly 15-20% heavier than a 22")
- Stress the bearings harder (more moment arm on the gang shaft)
The reverse — downsizing from 24 to 22 — leaves the blade closer to the frame, which changes hitch geometry and can cause the blades to no longer clear the frame at the ends of the gang.
Which machines use 22"
- Most vertical-tillage tools: JD 2623, Case IH True-Tandem 330/335, Krause Excelerator 8000, Great Plains Turbo-Till, Sunflower 6631
- Lighter tandem discs and vintage 3-point disc harrows
- Some coulter gangs on chisel plows
Which machines use 24"
- Modal tandem discs: Case IH 3900/3950, Krause 4900, Sunflower 1233/1234
- Most heavy tandem discs at mid-capacity
- Some vertical-tillage tools at the heavy end of the range (Krause TL6200)
Cut depth: what the two inches actually do
At a typical 18-degree gang angle, a 22" blade cuts about 4-5" deep in loose soil. A 24" blade at the same angle cuts about 5-6". That extra inch of depth is meaningful if you're doing primary tillage on tough ground — but on a vertical-tillage tool where the whole point is 2-3" of shallow, high-speed residue mixing, the deeper cut is a downside.
Vertical tillage prefers 20-22" blades because they run shallower at high speed, mixing residue into the top of the soil profile instead of burying it. Full-tillage disc harrows prefer 22-26" for real primary-tillage cut depth.
Wear rate: 24" lasts longer per inch
A blade is retired when its diameter drops below the manufacturer's minimum — usually 2" below the new-blade spec. That means a new 22" is retired at 20", and a new 24" is retired at 22". Both blades have 2" of useful edge. But the 24" has more mass in that 2" of edge, and it wears more slowly per hour because the same soil load is distributed across a larger circumference. In practice, a 24" blade lasts roughly 20-30% longer than a 22" of the same alloy and thickness.
Weight and handling
A 22" x 6mm carbon steel blade weighs about 20 lbs. A 24" x 6mm blade weighs about 26 lbs. Doesn't sound like much, but if you're changing a full 36-blade gang set on your own with a floor jack and a persuader, the difference between hauling 720 lbs of blades and 940 lbs of blades matters. Plan accordingly.
Cost per acre
A 22" blade in plain carbon runs about $70-85. A 24" runs about $85-105. The 24" is roughly 20% more expensive but roughly 25% longer-lived. Cost per acre works out very slightly cheaper on the 24" in equivalent soil, but the biggest variable isn't diameter — it's alloy (see our boron vs. carbon guide).
Shop by size
- 22-inch disc blades — vertical tillage and light tandems
- 24-inch disc blades — the modal size, most tandem discs
- 20-inch disc blades — vertical tillage and coulter setups
- 26-inch disc blades — heavy tandem and offset discs