Research-based guide · Updated October 11, 2026. We use manufacturer specifications and care instructions. We have not personally tested the products discussed here.
Quick verdict: Shortlist the RYOBI AC04020 only when your exact mower calls for this replacement. “20-inch” describes a size, not universal compatibility. This is a fit and buying guide; we have not measured cut quality or compared blade life.
Manufacturer-listed compatibility
RYOBI identifies these model pairs on its AC04020 page. Check the model label on your machine and its current parts list; retailer kit names and mower-body numbers can differ.
| RYOBI-listed model pair | Your check |
|---|---|
| RY40180 / RY40108 | Match the complete model number |
| RY40190 / RY40109 | Match the complete model number |
| RY401110 / RY401011 | Match the complete model number |
| RY401120 / RY401012 | Match the complete model number |
| RY40LM30 / RY40LM03 | Match the complete model number |
If your mower is not listed, stop and find its specified part. A similarly sized RYOBI mower can use a different blade or multi-blade arrangement. We do not recommend modifying a blade or using reducing washers to force a fit.
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Sharpen or replace?
Have a serviceable, dull blade assessed for sharpening and balancing under the mower’s instructions. Replace a bent, cracked or excessively worn blade with the approved part. A poor cut can also come from deck buildup, cutting height or mowing conditions, so a new blade is not a guaranteed cure.
Before you order
- Find the mower model and serial label.
- Confirm AC04020 in the relevant parts information.
- Check that the seller supplies the intended genuine part and appropriate condition.
- Read the installation instructions for orientation, hardware and torque, or arrange service.
Remove the battery and start key as directed, wait for all movement to stop and follow the manual before blade work. Use the specified hardware and torque rather than a generic online value.
How to compare an aftermarket blade
Compare documented fit for the exact mower and the specified blade arrangement, not appearance or width alone. We have not tested this blade against aftermarket alternatives, so we do not claim better steel, longer service life or superior cutting results.
The replacement-parts guide explains the wider shopping checks. Use the maintenance checklist for deck cleaning and seasonal inspection.
Common questions
Will it fit every RYOBI 20-inch mower?
No. Use the manufacturer’s model list and your mower’s parts documentation.
Does a replacement blade remove the need for sharpening?
No. Future maintenance depends on use and blade condition.
Can I install it on another brand?
This guide establishes no cross-brand compatibility. Use the blade approved for that mower.
Source: RYOBI AC04020 product and compatibility information.
