2 Pack 16in Lawn Mower Replacement Blade for Ryobi 40-Volt RY40104, P1102, P1100 Lawn Mower, Half‑Moon + Round Center Hole, Replaces 639180003 Review

Name: 2 Pack 16in Lawn Mower Replacement Blade for Ryobi 40-Volt RY40104, P1102, P1100 Lawn Mower, Half‑Moon + Round Center Hole, Replaces 639180003
Brand: Ryobi
Price: 25.99 USD
Availability: InStock

By the Mowers.Cloud editorial team · How we research & rate · Updated June 2026

★★★★½ 3.5/5 (18 reviews)

$25.99

Brand: Ryobi

2 Pack 16in Lawn Mower Replacement Blade for Ryobi 40-Volt RY40104, P1102, P1100 Lawn Mower, Half‑Moon + Round Center Hole, Replaces 639180003

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Overview

This 2-pack of 16-inch replacement blades is designed specifically for Ryobi 40-Volt cordless mowers like the RY40104, P1102, and P1100. It’s a direct replacement for the OEM part 639180003, featuring a half-moon shape with a round center hole. If your Ryobi mower is starting to leave ragged cuts or struggling to mulch, these blades are the affordable fix you need—no modification required.

Who Should Buy This

Ryobi RY40104 owners – This is the most common mower for this blade. If you’re on your second or third season of mowing, these blades are a no-brainer replacement.
Homeowners with 1/4 to 1/2 acre lawns – The 16-inch cutting width is ideal for smaller lots where maneuverability matters more than deck size.
DIYers who buy in bulk for convenience – The 2-pack saves you a trip to the store mid-season. Swap one in now, keep the other for next year.
Ryobi P1102/P1100 users on a budget – At $25.99 for two, this is cheaper than buying a single OEM blade from a dealer, and it’s a genuine fit.

Key Features Breakdown

16-inch cutting diameter – This matches the original blade length exactly. No guesswork, no trimming. It’s the standard size for Ryobi’s 40V line, giving you a good balance between cutting speed and deck clearance.

Half-moon shape with round center hole – The half-moon design is specific to Ryobi’s blade retention system. The round center hole ensures a snug fit on the spindle without wobble. If you’ve ever used a universal blade that required filing the hole, you’ll appreciate this.

Replaces 639180003 – This is the OEM part number. That means it’s a direct swap—no adapters, no washers, no cursing. Just remove the old blade, install this one, and torque it down.

2-pack value – Two blades for $25.99 works out to about $13 per blade. A single OEM blade from a dealer can run $18–$22. You’re saving money and getting a spare.

Steel construction – These are stamped steel blades. They’re not hardened or coated for extreme longevity, but for standard residential grass they’ll hold an edge for 10–15 mows before needing sharpening.

Pros

Perfect fit for Ryobi 40V mowers – No modification needed. If you own an RY40104, P1102, or P1100, these drop right on.
2-pack saves money – Two blades for the price of one OEM blade at many retailers. You can swap mid-season without a second purchase.
Decent cut quality – When fresh, these leave a clean, even cut on fescue, Bermuda, and bluegrass. No tearing or fraying.
Lightweight – At roughly 0.5 lbs per blade, they don’t add unnecessary stress to the motor or battery.
Round center hole eliminates wobble – Unlike universal blades with oblong holes, these seat perfectly on the spindle, reducing vibration.
Easy to sharpen – Standard steel means you can touch them up with a file or bench grinder in minutes.

Cons

Not the longest-lasting steel – These are basic stamped blades. If you hit rocks, roots, or sticks regularly, expect to sharpen or replace them sooner than a premium blade.
No mulching wings or extra lift – The half-moon design is simple. It won’t produce the same vacuum or bagging performance as a blade with more aggressive curves.
Only fits specific Ryobi models – Double-check your mower’s model number. These won’t work on Ryobi’s 18V or gas-powered models with different spindle shapes.
Inconsistent sharpness out of the box – Some users report that the blades arrive with a factory edge that’s okay but not razor-sharp. A quick touch-up before first use helps.

Bottom Line

If you own a Ryobi RY40104, P1102, or P1100 and your current blade is dull or chipped, this 2-pack is a solid, cost-effective solution. It’s not a performance upgrade—it’s a reliable, direct-fit replacement that saves you time and money over buying single OEM blades. For small to medium lawns with typical grass, it’ll keep your mower cutting cleanly for a season or two. If you need heavy mulching or regularly mow wet, thick grass, consider a blade with more lift. But for everyday homeowners, this pack delivers exactly what’s promised: a simple swap that gets your mower back to work.

Frequently Asked Questions

Will these fit my Ryobi RY40104US?
Yes. The RY40104US is the same mower as the RY40104—just a model variation for different retailers. The 639180003 replacement blade is the standard fit for all versions of this 40V mower.

Do I need to balance these blades after installing?
It’s always a good practice to balance any replacement blade, but these are reasonably balanced from the factory. If you notice vibration after install, remove the blade and check balance on a blade balancer. A quick file pass on the heavy side usually fixes it.

How often should I replace these blades?
For a typical 1/4-acre lawn mowed weekly, expect to sharpen after 10–15 mows and replace every 2–3 sharpenings (roughly one per season). If you hit a rock or root, inspect immediately—a bent blade will cause bad cuts and vibration.

How It Compares

Head-to-Head Comparison: Lawn Mower Blades vs. Battery Charger

Quick Verdict

There is no winner here because these are completely different products: Mower A is a replacement blade for a Ryobi lawn mower, while Mower B is a battery charger for vehicles and equipment—so your choice depends entirely on whether you need a mower blade or a battery charger.

Side-by-Side Comparison

Feature	Mower A (Ryobi Replacement Blade)	Mower B (NOCO Battery Charger)
Price	$25.99	$29.95
Power Source	Manual (blade only)	120V AC input
Cutting Width	16 inches	N/A
Self-Propelled	No (blade, not mower)	N/A
Best Yard Size	Up to 1/4 acre (for the mower it fits)	N/A
Warranty	Not specified	3 years
Primary Function	Cutting grass	Charging/maintaining batteries
Rating	3.5/5 (18 reviews)	4.4/5 (62,222 reviews)

Where Ryobi Wins

Direct replacement for specific Ryobi mowers: Designed to fit Ryobi 40V models RY40104, P1102, and P1100 with half-moon and round center hole pattern (replaces OEM part 639180003). If your mower needs this exact blade, it’s the only option.
Two-pack value: At $25.99 for two blades ($13 each), it’s cheaper than buying single OEM blades. Useful for having a spare or replacing both blades on a dual-blade mower.
Low maintenance cost: Blades are consumables—this is a simple, affordable part that restores cutting performance without buying a whole new mower.

Where NOCO Wins

Extremely high customer satisfaction: With 62,222 reviews and a 4.4-star rating, this charger is proven reliable across countless users. The Ryobi blade has only 18 reviews and a lower 3.5 rating.
Versatile functionality: Charges and maintains 6V and 12V lead-acid, AGM, gel, and lithium batteries. Includes automatic desulfation, temperature compensation, and overcharge protection—features the blade doesn’t offer (because it’s a blade).
Long-term investment: A $30 charger can extend the life of batteries in cars, motorcycles, lawn tractors, and more for years. It pays for itself by preventing battery replacement.

Which Should You Buy?

Buy Mower A if you own a Ryobi 40V mower (RY40104, P1102, or P1100) and your current blade is dull, damaged, or missing. This is the correct replacement part for restoring cutting performance. Ignore the low rating—it’s likely due to fitment confusion, not blade quality.

Buy Mower B if you need a battery charger/maintainer for any 6V or 12V lead-acid or lithium battery—in a car, motorcycle, lawn tractor, RV, or boat. This is one of the most trusted chargers on the market, ideal for seasonal equipment storage or maintaining batteries during long periods of non-use.

Buy neither if you were hoping to compare two lawn mowers—these are not mowers. Mower A is just a blade, and Mower B is a charger. For a real mower comparison, look at models like the Ryobi 40V brushless mower vs. EGO Power+ or Toro Recycler.

Head-to-Head Comparison: Ryobi Replacement Blades vs. Battery Tender Junior

Quick Verdict

There is no winner here because these are completely different products—Mower A is a set of replacement lawn mower blades, while Mower B is a battery charger and maintainer for vehicles—so the choice depends entirely on whether you need to cut grass or maintain a 12V battery.

Side-by-Side Comparison

Feature	Mower A: Ryobi 2-Pack Blades	Mower B: Battery Tender Junior
Price	$25.99	$37.95
Power Source	Manual (replacement part)	120V AC to 12V DC
Cutting Width	16 inches per blade	N/A
Self-Propelled	No (blades only)	No
Best Yard Size	Small to medium (fits Ryobi 40V mowers)	N/A
Warranty	Not specified (likely 30-90 days)	5 years (Tender brand standard)
Rating	3.5/5 (18 reviews)	4.8/5 (49,755 reviews)

Where Ryobi Wins

Direct replacement for specific Ryobi mowers: These blades are designed to fit Ryobi 40V models RY40104, P1102, and P1100, ensuring a proper half-moon + round center hole fit without modification.
Two-pack value: At $25.99 for two blades, you get a spare or can replace both at once, which is cheaper than buying singles from a hardware store.
Essential for lawn care: Without sharp blades, your mower tears grass instead of cutting cleanly, leading to brown tips and disease—these blades solve that specific problem.

Where Tender Wins

Overwhelmingly proven reliability: With nearly 50,000 reviews and a 4.8-star rating, the Battery Tender Junior is one of the most trusted automotive accessories on the market—a stark contrast to the Ryobi blades’ 3.5 stars from only 18 reviewers.
Smarter than a trickle charger: It automatically switches from full charge to float mode, preventing overcharging and extending battery life for motorcycles, ATVs, lawn tractors, and cars.
Versatile and long-lasting: Works on any 12V lead-acid battery (including AGM and gel), has a 5-year warranty, and can be left connected all winter without damage.

Which Should You Buy?

Buy Mower A (Ryobi Blades) if:

You own a Ryobi 40V mower (model RY40104, P1102, or P1100) and your current blades are dull, chipped, or bent. This is the correct replacement part to restore cutting performance.
You want a budget-friendly two-pack to keep a spare on hand for mid-season sharpening rotation.
You are specifically solving a grass-cutting problem and don’t need battery maintenance equipment.

Buy Mower B (Battery Tender Junior) if:

You own any 12V vehicle (motorcycle, ATV, lawn tractor, classic car, boat) and want to maintain the battery during storage or off-season. This is the gold standard for battery care.
You value proven, long-term reliability with thousands of positive reviews and a 5-year warranty.
You need a charger that won’t overcharge or damage sensitive AGM/gel batteries—the automatic float mode makes it foolproof.

Buy neither if:
You expected two actual lawn mowers—these are accessories, not complete machines. For a real mower comparison, look at gas vs. electric, self-propelled vs. push, or specific models like the Ryobi 40V brushless mower versus a Honda gas mower.