Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
A replacement lawn mower blade has to match the mower it goes on in several ways at once, and "universal fit" on the packaging does not make that check unnecessary. The overall length has to match, measured from tip to tip rather than along the curved cutting edge. The center hole has to match the mower's spindle, and any smaller side holes have to match too. The blade type — a mulching blade, a high-lift blade or a standard blade — has to suit how your mower discharges or bags clippings. Getting any one of these wrong is not a minor inconvenience: a blade that is longer than the mower deck can strike the housing while the blade spins.
This page shows you how to find the model and serial number your mower's manufacturer needs to look up the exact blade, and how to measure an old blade you already have on hand as a cross-check. It does not give you a single length or hole size that applies to every mower, because none exists — Toro alone lists a distinct blade for dozens of different deck widths. It also does not cover removing the old blade or fitting the new one; that is a separate job with its own hazards. If your measurements do not match what the manufacturer lists, the safest step is to ask the manufacturer or an authorized dealer rather than guess.
Necessary equipment
| Item | Note |
|---|---|
| Ruler or tape measure | A ruler or a tape measure gives the blade length and the hole size. |
| Vernier caliper optional | A caliper gives an exact reading of the center hole. |
| Pen and paper | Pen and paper record every measurement together. |
| Phone with a camera optional | A photograph is a backup record of the identification plate. |
| Operator manual for your mower | The manual gives the plate location and the blade part number. |
| Heavy gloves | Heavy gloves protect your hand from the sharp edge. |
Find the model and serial number
Estimated 3 min to 6 min
- Find the identification plate on your mower.<1mReport a problem with step 1, Find the model and serial number
- The plate can be on the deck, the handle or the frame.
- Read the model number from the plate.<1mReport a problem with step 2, Find the model and serial number
- Read the serial number from the plate.<1mReport a problem with step 3, Find the model and serial number
- If you cannot find the plate, open the operator manual.1mReport a problem with step 4, Find the model and serial number
- Take a photograph of the plate with a phone.<1mReport a problem with step 5, Find the model and serial number
- A photograph keeps every character together.
Find the blade for your mower
Estimated 4 min to 12 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
DO NOT BUY A BLADE BECAUSE IT SAYS UNIVERSAL.
A universal blade can be the wrong blade for your mower.
- Open the manufacturer parts lookup for your mower.1mReport a problem with step 1, Find the blade for your mower
- Enter the model number and the serial number.
- Find the blade that matches your exact model.<1mReport a problem with step 2, Find the blade for your mower
- A riding mower can carry a separate tag for the mower attachment.
- Read the blade type on the parts list.<1mReport a problem with step 3, Find the blade for your mower
- A mulching blade cuts clippings into small pieces.
- A high-lift blade moves the grass toward a catcher or a chute.
- A low-flow blade suits a dry or a dusty lawn.
- A recycler blade has wings that force clippings into the lawn.
- Write the blade part number on paper.<1mReport a problem with step 4, Find the blade for your mower
- If the lookup shows no result, speak to an authorized dealer.1mReport a problem with step 5, Find the blade for your mower
Measure the old blade as a check
Estimated 4 min to 6 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
- Make sure the old blade is separate from the mower.<1mReport a problem with step 1, Measure the old blade as a check
- This page gives no removal procedure for the blade.
WEAR HEAVY GLOVES BEFORE YOU TOUCH THE BLADE.
A sharp edge can cut your skin.
- Put on the heavy gloves.<1mReport a problem with step 2, Measure the old blade as a check
- Find the two ends of the blade.<1mReport a problem with step 3, Measure the old blade as a check
- A mower blade often has a different shape at each end.
- Measure from the tip of one end to the tip of the other end.<1mReport a problem with step 4, Measure the old blade as a check
- Measure through the center hole.
- Do not measure along the curved edge.
- Write the length measurement on paper.<1mReport a problem with step 5, Measure the old blade as a check
- Measure the diameter of the center hole.<1mReport a problem with step 6, Measure the old blade as a check
- The center hole fits over the mower spindle.
- Write the center hole measurement on paper.<1mReport a problem with step 7, Measure the old blade as a check
- Look for a small hole on each side of the center hole.<1mReport a problem with step 8, Measure the old blade as a check
- Not every blade has side holes.
- If the blade has side holes, measure the distance between them.<1mReport a problem with step 9, Measure the old blade as a check
- Write the side hole measurement on paper.<1mReport a problem with step 10, Measure the old blade as a check
- Look at the shape of each end of the blade.<1mReport a problem with step 11, Measure the old blade as a check
- A curled or a notched end often marks a mulching blade.
- A raised or a twisted end often marks a high-lift blade.
Compare every measurement before you buy
Estimated 2 min to 6 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
DO NOT BUY A BLADE LONGER THAN YOUR MOWER DECK.
A blade longer than the deck can strike the housing. A broken piece can injure you.
- Compare the length of the new blade with the width of your mower deck.<1mReport a problem with step 1, Compare every measurement before you buy
- Compare your measurements with the manufacturer's parts list.<1mReport a problem with step 2, Compare every measurement before you buy
- If a measurement does not match, speak to the manufacturer or an authorized dealer.1mReport a problem with step 3, Compare every measurement before you buy
Record your findings
Estimated under a minute
- Keep your written measurements with the model and serial number.<1mReport a problem with step 1, Record your findings
- Take the record with you when you buy a new blade.<1mReport a problem with step 2, Record your findings
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- replacement mower blade
- Also called: what size blade fits my mower, new lawn mower blade, blade for my mower, correct mower blade
- center hole
- Also called: centre hole, mower blade centre hole size, arbor hole, spindle hole, blade bore
- mounting hole pattern
- Also called: bolt pattern, hole pattern, side holes
- mulching blade
- Also called: mulcher blade, gator blade, high lift vs mulching blade
- high-lift blade
- Also called: high lift blade, hi-lift blade, hi-flow blade, bagging blade, 2-in-1 blade
- universal blade
- Also called: universal lawn mower blade, universal fit blade, will any blade fit my mower
- blade measurement
- Also called: how to measure a lawn mower blade, measuring a mower blade, blade length measurement
When to use a professional
If a measurement does not match the manufacturer's parts list, speak to the manufacturer or an authorized dealer. If the lookup shows no result for your model, speak to the manufacturer. This page gives no removal procedure and no installation procedure for the blade. A service dealer can remove the old blade and fit the new blade. If the deck or the spindle has damage, speak to a service dealer.
Common questions
What size blade fits my mower?
There is no single size that fits every mower, so this is not a question a general chart can answer safely. Toro, for one, tells shoppers directly to verify the model and serial number on their own machine before they buy a part, because dozens of deck widths each take a different blade. The fastest route is the manufacturer's parts lookup, keyed to your model and serial number rather than to the mower's brand or a general size class. If you already have the old blade in hand, measuring it as a cross-check is worthwhile too.
How do I measure a lawn mower blade to buy a replacement?
Measure the straight distance between the tip of one end of the blade and the tip of the other, through the center hole, not along the curved cutting edge, which reads shorter. Fisher Barton, a major manufacturer of OEM mower blades, explains that most blades are not the same shape at each end, which is why a tip-to-tip measurement is the standard rather than a straight edge-to-edge one. Also record the center hole's diameter and, if your blade has them, the distance between any smaller side holes. All three numbers, plus the blade's lift or mulching style, are what a replacement has to match.
What is the center hole on a mower blade, and does its size really matter?
The center hole is the opening that fits over the mower's spindle, and it has to match closely enough that the blade sits true when it is tightened down. Too large and the blade can wobble off-center; too small and it will not seat on the spindle at all. Fisher Barton's own measuring guidance treats the center hole as one of the two or three most important numbers on the whole blade, alongside the overall length.
Is there really such a thing as a 'universal' lawn mower blade?
Treat that word with suspicion. Toro's own guidance is blunt about it: using an ordinary blade in a Toro mower, its documentation warns, can cause unexpected wear and breakage to the machine while leaving the grass frayed and unhealthy. A blade marketed as universal may fit the bolt and still be the wrong length, the wrong center hole or the wrong lift type for your specific deck; "universal" usually means the mounting hardware is adjustable, not that every dimension is a safe match. Check the length, the center hole and the hole pattern yourself regardless of what the packaging claims.
What is the difference between a high-lift blade and a mulching blade?
A high-lift blade, which Toro also calls a Hi-Flow blade, is built to pull grass upward and push it out through a discharge chute or into a bagger, and it moves more air than the other common blade styles. A mulching blade is built to keep clippings under the deck longer, cutting them into finer pieces that settle back into the lawn instead of leaving the deck at all; Toro's Atomic and Recycler blades are both variations on this idea. A low-flow blade sits at the other end of the spectrum, designed for sandy or dusty conditions where a high-lift blade's extra suction just stirs up debris. Your mower's manual or its manufacturer's parts listing will say which type the deck was designed around, and swapping types changes how clippings are handled, not just how the blade looks.
I can't find the model or serial number plate on my mower. What do I do?
Check your owner's manual or quick start guide first; Toro explicitly tells owners to check there when the physical plate cannot be found or has worn away. If that does not turn up an answer, Toro's own advice is to bring the machine to an authorized service dealer, who can identify it from the equipment itself. Do not guess at a part number from memory or from a similar-looking machine online; a wrong guess is how the wrong-length blade ends up under the deck.
Can I install a blade that's a little longer than the original, as long as it fits the mounting bolt?
No; treat that as a hard no, not a judgment call. A blade longer than the mower deck can strike the housing once the mower is running, and a piece breaking off at that point is a real hazard, not just a fit issue. The bolt pattern matching is not enough on its own: length, center hole and hole pattern all have to match together, and length is the one most likely to cause damage if it is wrong. If you cannot confirm the length from the manufacturer's listing, treat that blade as the wrong blade rather than assuming a close match is safe.
Related procedures
- How to find and record the model and serial number of every appliance in the house
- Find the exploded parts diagram for a machine you own, and read a part number off it
- Level a riding mower deck side to side and front to rear on flat ground
- What size blade fits my circular saw, and does the RPM rating on the blade matter?
- What chain fits my chainsaw? How to check pitch, gauge, and drive link count
- What size filter do I need, and is a generic or cross-reference filter really the same as the OEM part?
- How to clean or change the air filter on a lawn mower
- How to change the spark plug on a lawn mower
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
- Tier 1Find Your Toro Model & Serial Number Plate
- Tier 1Toro Model & Serial Number Lookup Help
- Tier 1Genuine Parts, Blades
- Tier 120.5 Inch Low Flow Blade (140-4854)
- Tier 120.5 Inch Hi-Flow Blade (138-8893-03)
- Tier 122.5 Inch 60V Atomic Mower Blade (144-3177-03)
- Tier 122 Inch Recycler Blade (59534P)
- Tier 1How to Measure Lawn Mower Blades
Revision history
Current version 1 · updated 2026-08-03 · next review due 2027-08-03
- v1 · 2026-08-03First draft. Scope is identification only: finding the model and serial number, using the manufacturer's parts lookup, and measuring an already-removed blade as a cross-check by length (tip to tip, not along the cutting edge), center hole diameter, and side-hole spacing. Blade part number, length, center hole, hole pattern and lift/mulching type all publish as consult-the-manufacturer instructions, never as a guessed number, because these are per-model values and Toro's own product pages repeat the same instruction to verify the model and serial number rather than rely on a general chart. Sourced to seven Toro manufacturer pages (the model/serial plate locator, the parts lookup help page, the genuine-parts blades page, and four blade product pages covering Low Flow, Hi-Flow, Atomic and Recycler types) and to Fisher Barton, the OEM manufacturer that supplies rotary mower blades to most major brands, for the tip-to-tip measuring method and the center-hole/side-hole instructions — the manufacturer confirmation the backlog entry asked for before that method could be stated with authority. Scope deliberately excludes removing the old blade or fitting the new one; that combined job carries its own torque value and its own hazards and belongs to the operator manual or a service dealer, not this record. No competitor page was opened while drafting; a small number of retailer measuring guides were noted only to confirm that Fisher Barton, a manufacturer, states the same method independently, per the backlog's sourcing note. All seven Toro sources and Fisher Barton are newly proposed and are in data/sources-additions-identify-the-correct-replacement-mower-blade.json pending admission.
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.