Mower Blade Offset and Pitch Explained
2026-11-10 · 7 min read
Mower blade offset is the step between the centre-hole plane and the cutting edge, while pitch is the blade's built-in angle of attack, and both decide cut height and deck clearance rather than just the fit. Get either wrong and the blade mounts but cuts at the wrong height or fouls the housing.
Why do offset and pitch matter?
Offset and pitch matter because a blade can be the right length and hole yet still cut badly if its step and angle are wrong. Offset sets where the cutting plane sits relative to the spindle; pitch sets how aggressively the blade meets the grass. Together they decide cut height, discharge and whether the blade clears the deck.
Most fit problems people call "wrong blade" are actually wrong offset or pitch, not wrong length. Our blade measuring guide shows how to record both, and the model index lists the profile details for each blade we cut.
What is blade offset?
Blade offset is the vertical step between the centre-hole plane and the cutting plane, because some blades are flat while others are cranked or stepped to sit at a set height. A flat blade has zero offset; a cranked blade drops the cutting edge below the hole plane. Offset is what keeps the blade at the designed cut height.
| Offset type | Cutting plane vs hole | Typical use |
|---|---|---|
| Flat (0 offset) | Level with hole | Many walk-behind decks |
| Cranked / stepped | Below hole plane | Rider and zero-turn decks |
| High-lift stepped | Below hole, with sail | Bagging decks |
These offset styles put the cutting edge at the height the deck was designed around, so matching the step matters as much as matching the length. A 942-0610a mulching blade and a 942-04308 high-lift blade show two different offset profiles in our range.
What is blade pitch?
Blade pitch is the fixed angle of attack built into the blade, because the metal is twisted or angled so the leading edge meets the grass at a set rake. Pitch is what lifts and discharges the clippings; too little and the blade scalps or recirculates, too much and it draws excess power. Pitch is designed, not adjusted in the field.
Most deck blades run a small positive pitch that lifts clippings into the chute, while mulching blades use a different rake to recut. The 482877 mulching blade carries the profile and pitch tuned for fine recutting on a 48-inch deck. Matching the pitch to the job is part of choosing the right blade type.
How do you measure offset and pitch?
Measure offset by checking the step from the centre-hole plane down to the cutting plane, and measure pitch by laying the blade on a flat surface and reading the angle of the cutting face. Offset is a height difference; pitch is an angle, so they need different checks. Both are easier to record from the old blade than to guess from the deck.
Take a side photo of the old blade resting on a flat board, with the centre hole plane and one cutting tip visible, so the step reads clearly. Our measuring guide lists the full set of facts to send, and the model index shows the profile each of our blades uses.
Can you change offset or pitch on a blade?
You cannot safely change offset or pitch on a finished blade, because both are set during forging and heat-treat and grinding them off weakens the steel. A blade that needs a different step or rake needs a different profile, not a modified one. Ordering the correct profile is the only reliable fix.
This is why confirming offset and pitch from the old blade matters before you order, especially for rider and zero-turn decks where the step is pronounced. Send the number or a photo and we will confirm the profile, including its offset and pitch, before any cutting begins.
What steel and hardness should an offset blade use?
An offset blade should be cut from 40Mn manganese steel and hardened to a 45–50 HRC band, which holds the edge through grit yet resists cracking on hidden stone. The offset and pitch set the cut; the steel and heat-treat set how long it lasts.
We run production in Guangde, Anhui, where the plant has made blades since 2008 and now employs more than 800 people with a daily capacity of 50,000 pieces. The same heat-treat control is detailed on our quality page, which is the part of production that most affects working life.
Frequently Asked Questions
Can a flat blade replace a cranked blade?
A flat blade should not replace a cranked blade, because the missing step puts the cutting edge at the wrong height and can foul the deck housing. The offset is part of the fit, so match the step to the original profile rather than substituting a flat blade.
Does pitch affect bagging performance?
Pitch affects bagging performance, because more angle of attack lifts clippings harder into the chute, while too little pitch lets them recirculate. High-lift blades use a steeper rake for bagging; mulching blades use less. Match the pitch to how you handle clippings.
How do I know if my blade offset is wrong?
You know the offset is wrong when the blade mounts but cuts unevenly, scalps one side, or rattles against the deck housing. Those are signs the cutting plane sits at the wrong height, not that the length or hole is wrong.
Are your offset blades original equipment parts?
We are an independent manufacturer and not an authorised dealer, so our blades are not original factory parts. They are made to match the original specifications of the part number you send, cut from 40Mn steel and held in the 45–50 HRC band.
What is the minimum order for custom offset blades?
The minimum order is 300 pieces per profile, which covers the setup and heat-treat run for a made-to-sample blade. Send the old blade or its number and we will confirm the offset, pitch, profile and run size before cutting.
More on this: How Mower Blades Are Made: From Steel to Sharp Edge · 10B38 Boron Steel vs 40Mn Mower Blades
Blade part numbers linked to this article
The model pages below carry the deck size, centre hole, thickness and replacement numbers for the blades discussed above.