RB 40V 9" Mini Cordless Lawn Mower with Battery & Charger for Small Yards | Ultra-light with brushless motor. 3 cutting heights. One-hand steering. Upright storage for tiny spaces, small lawns, patios. Review

Overview

The RB 40V 9" Mini Cordless Lawn Mower is a purpose-built machine for the smallest of cutting jobs—think postage-stamp lawns, tight patios, and awkward nooks where a full-size mower feels like overkill. With its ultra-light 9-inch deck, brushless motor, and single-hand steering, this mower is designed for homeowners who need a quick, quiet trim without wrestling with a gas can or a heavy machine. It’s best for anyone with under 1,000 square feet of grass who values compact storage and simple operation.

Who Should Buy This

Small-lot homeowners with tiny front yards – If your lawn is more of a green doormat than a sprawling field, this mower saves you from dragging out a 40-pound gas beast. Perfect for yards under 500 square feet.

Apartment or condo dwellers with patio grass – Got a strip of turf on a balcony or a tiny courtyard? This mower’s 9-inch width and upright storage let you tuck it in a closet after a 5-minute cut.

Homeowners who hate gas and oil – If you’re tired of stale fuel, carburetor cleanings, and the smell of exhaust, the RB’s 40V battery system is a no-brainer. Just charge and go.

Seniors or anyone with limited strength – At under 15 pounds with one-hand steering, this mower is genuinely easy to push, turn, and lift. No yanking a starter cord or wrestling with a heavy deck.

Key Features Breakdown

9-inch cutting deck – This is a mini mower, not a standard one. The narrow deck means you can weave between flower beds, under shrubs, and along tight fence lines. But it also means more passes on anything larger than a postage stamp. For a 300-square-foot patch, you’ll finish in under 10 minutes.

40V brushless motor – Brushless motors are more efficient and longer-lasting than brushed ones. This one delivers consistent power to the blade without bogging down on thin grass, though thick or wet grass will test its limits. The 40V battery (included) gives about 20-25 minutes of runtime—enough for most small jobs.

3 cutting heights – Adjustable via a single lever, with positions roughly 1, 1.5, and 2 inches. That’s limited compared to full-size mowers, but for a mini mower, it covers the basics. You won’t be scalping your lawn, but you also can’t go super high for a “lawn meadow” look.

One-hand steering – The handle is a simple T-bar that lets you steer with one hand while you hold a drink or a phone in the other. It’s genuinely easy to maneuver and pivot, especially in tight spaces.

Upright storage – The mower folds flat and stands on its end, taking up about the same floor space as a small suitcase. If you live in an apartment or have a packed shed, this is a game-changer.

Ultra-light design – At roughly 13 pounds without the battery (just under 15 with it), you can easily carry it up stairs, load it into a car trunk, or hang it on a wall hook.

Pros

• Truly lightweight and portable – You can lift it with one finger. No other cordless mower under $200 comes close.
• Great for tight spaces – The 9-inch deck fits where standard 14- to 20-inch mowers can’t, like between raised garden beds or under a low deck.
• Quiet operation – At around 70 decibels, it’s quieter than a gas mower and won’t annoy neighbors. You can even mow early on a Saturday.
• Simple one-hand steering – The T-bar handle makes turning effortless, especially on small, irregularly shaped lawns.
• Compact upright storage – Folds flat and stands vertically, so it hides in a closet or corner without taking up floor space.
• Brushless motor efficiency – No brushes to wear out, and the battery lasts longer per charge than a brushed motor would.

Cons

• Limited runtime – The 40V 2.0Ah battery gives about 20-25 minutes of cutting. For a 1,000-square-foot lawn, you might need a second battery to finish without recharging.
• Small deck means more passes – On anything larger than 500 square feet, you’ll be walking back and forth a lot. This is not a time-saver for medium lawns.
• No grass bag included – The mower mulches clippings back into the lawn, which is fine for light trimming, but if you want to collect clippings, you’ll need to buy a separate bag (not included).
• Not for thick or tall grass – The brushless motor is decent, but the 9-inch blade and low cutting height struggle with dense, overgrown grass. You’ll need to take multiple passes or cut more frequently.

Bottom Line

The RB 40V 9" Mini Cordless Lawn Mower is a niche tool that excels at exactly what it promises: quick, quiet, one-hand trimming of tiny lawns, patios, and tight spaces. It’s not a replacement for a full-size mower—don’t buy it for a quarter-acre lot—but for anyone with under 500 square feet of grass who values compact storage and zero gas hassle, it’s a near-perfect solution. The lack of a grass bag and limited runtime are real trade-offs, but the price is fair, the build is solid, and the convenience is unmatched. If your lawn fits on a postage stamp, this mower is a clear buy.

Frequently Asked Questions

Can I use this mower on a standard 1/4-acre lawn?
No, not effectively. The 9-inch deck and 20-minute runtime mean you’d need to recharge the battery 3-4 times and make dozens of passes. It’s designed for lawns under 1,000 square feet—think tiny front yards, patios, or narrow strips.

Does the battery work with other RB tools?
Yes, the RB 40V battery is shared across their line of outdoor tools (trimmers, blowers, etc.). If you already own RB 40V gear, you can swap batteries, which is a nice bonus.

How do you adjust the cutting height?
There’s a single lever on the side of the deck. You push it to one of three positions (low, medium, high). It’s tool-free and takes about 3 seconds. Just make sure the mower is off when you adjust it.