Taming a demanding lawn, whether it features rolling hills or dense, spring growth, often feels like a workout rather than a chore. Traditional push mowers can quickly lead to fatigue, especially when navigating expansive or uneven terrain.
Fortunately, the self-propelled category eliminates this physical strain by propelling itself forward, allowing you to simply guide the machine to achieve a professional-quality cut.
We have meticulously analyzed the market’s top 21-inch self-propelled models—including robust gas-powered options and high-torque cordless electric units—to help you find the perfect machine that matches your yard size and maintenance priorities.
Investing in the right self-propelled mower guarantees consistent results while maximizing your time and minimizing effort.
1. Greenworks 80V 21″ Self-Propelled Mower – Best Overall
This premium cordless electric mower stands out by delivering robust, gas-like performance paired with the convenience of an 80V battery system.
Equipped with a high-torque brushless motor and a durable 21-inch steel deck, this machine effortlessly cuts through thick grass with authority.
It features self-propelled rear-wheel drive and variable speed control, allowing users to adapt the mowing pace seamlessly to terrain and grass conditions.
Designed for eco-conscious homeowners with half-acre lots and beyond, the Greenworks 80V operates up to 3x quieter than comparable gas models.
The included 4.0Ah battery provides up to 45 minutes of runtime on mixed-height lawns, and LED headlights enable early morning or late evening operation without disturbing neighbors. This machine offers a perfect balance of power and eco-friendly efficiency.
Best For: Homeowners demanding cutting-edge cordless power and quiet, high-performance operation on medium to large suburban yards (up to 1/2 acre).
Key Specs:
| Battery Voltage | 80V |
|---|---|
| Deck Size | 21″ |
| Motor Type | Brushless |
| Battery Capacity | 4.0Ah |
Pros
- High-torque, gas-like cutting power
- Variable speed control for slopes
- Quiet, low-maintenance operation
- Advanced 4-in-1 versatility
- Built-in LED headlights extend use
Cons
- Higher initial purchase cost
- Reduced runtime in wet grass
- Battery degrades over time
2. PowerSmart 21″ B&S Self-Propelled – Best Budget Friendly
The PowerSmart 21-inch mower proves that reliable self-propelled performance doesn’t require a premium price tag.
Earning the “Best Budget Friendly” title, it utilizes a dependable Briggs & Stratton 140cc engine that ensures smooth startup and consistent power for medium to large lawns.
The 21-inch steel deck and rear-wheel drive provide solid traction, especially beneficial on dry, overgrown grass and mild slopes.
This gas mower delivers no-nonsense reliability and fundamental performance with its 3-in-1 functionality (bagging, mulching, rear discharge).
The single-lever, 6-position height adjustment makes customizing the cut height across the 1.5″ to 3.9″ range quick and uniform.
It’s an ideal gateway mower for buyers prioritizing self-propelled ease and dependable cutting without expensive features.
Best For: Cost-conscious buyers needing dependable, gas-powered performance and reliable startups for medium-sized yards.
Key Specs:
| Engine | B&S 140cc |
|---|---|
| Cutting Width | 21-inch |
| Function Modes | Bag/Mulch/Rear Discharge |
| Height Adjustment | 1.5″ to 3.9″ |
Pros
- Dependable B&S 140cc engine
- Strong cutting performance for price
- Rugged steel deck construction
- Runs indefinitely with fuel
- Effective single-lever height adjustment
Cons
- Noisy gas engine operation
- Small 1.4-bushel bag capacity
- Lacks variable speed control
3. Greenworks 60V 21″ Self-Propelled – Best Mid-Range
The Greenworks 60V model skillfully occupies the sweet spot between value and power in the electric category, delivering genuine cordless freedom without the cost of the 80V system.
This unit comes standard with dual 4.0Ah batteries, providing up to 45 minutes of continuous mowing—suitable for most 1/3 to 1/2 acre properties.
The 60V brushless motor delivers consistent torque, handling medium-height grass effectively. Its self-propelled rear-wheel drive is helpful for moving uphill, and the LED headlights extend the usable mowing window.
Furthermore, this mower integrates into the wider Greenworks 60V tool ecosystem. This is a smart investment for users seeking dependable, eco-friendly operation with the added benefit of battery redundancy and rapid recharging capability.
Best For: Users seeking an expandable, reliable electric platform with included battery redundancy and strong performance for medium lawns.
Key Specs:
| Battery Voltage | 60V |
|---|---|
| Runtime | 45Min |
| Batteries Included | 2X 4.0Ah |
| Compatibility | 75+ tools |
Pros
- Dual battery redundancy included
- Integrates into large tool ecosystem
- Brushless motor maintains strong torque
- LED lights for dusk mowing
- Excellent mid-range value proposition
Cons
- Less powerful than 80V models
- Runtime drops in very thick grass
- Battery replacement cost possible
4. BILT HARD 21″ Self Propelled Mower – Best for Large Yard
For homeowners facing expansive properties or seriously overgrown fields, the BILT HARD is engineered for raw, uncompromising power.
It features a substantial 201cc 4-cycle OHV engine that generates 9.0 ft·lb of torque—significantly more muscle than typical budget gas models.
This engine allows for effortless cutting through the tallest, wettest, or densest grass patches. Precision is handled by an 8-position, single-lever height adjustment system, ranging from 1.2″ to 3.75″. The reliable rear-wheel drive ensures confidence on sloped and uneven terrain.
A no-choke, no-primer start system ensures ignition reliability every time. This mower prioritizes brute reliability and cutting performance over convenience features like LED lights, making it the best choice for large, demanding yards.
Best For: Large properties (half-acre and above) or challenging terrain where maximum engine power and high torque are essential for heavy use.
Key Specs:
| Engine Type | 201cc 4-cycle OHV |
|---|---|
| Deck Size | 21 inch |
| Height Adjustment | 8 positions |
| Functions | 3-in-1 |
Pros
- Massive 201cc OHV engine power
- Superior cutting ability in dense grass
- 8-position precise height control
- Highly reliable, easy start system
- Excellent durability for large yards
Cons
- Heavier than electric alternatives
- Loud operation and emissions
- Bulky due to gas construction
5. PowerSmart 21″ B&S Self-Propelled – Best for Reliability
This PowerSmart model, built around the dependable Briggs & Stratton 140cc engine, is the ultimate workhorse for users who value simplicity and unflinching consistency.
It is designed to start consistently and perform without stalling, maintaining steady RPMs even when faced with moderately tough conditions.
The mower boasts a durable 21-inch steel deck and reliable rear-wheel drive with 10-inch rear wheels that navigate ruts and uneven ground smoothly.
Its strength lies in its minimal complexity; it runs indefinitely on fuel and requires only standard, basic maintenance.
While it lacks advanced features like variable speed, its rock-solid performance and simple 6-position height adjustment earn the trust of users looking for a no-fail machine that delivers clean cuts year after year.
Best For: Homeowners prioritizing consistent, long-term durability and minimal downtime over high-tech features, especially those who prefer unlimited runtime.
Key Specs:
| Engine | B&S 140cc |
|---|---|
| Deck Material | Steel |
| Cutting Options | 3-in-1 |
| Height Adjustment | 6 positions |
Pros
- Unflinching 140cc B&S engine
- Durable steel deck construction
- Simple, reliable starting mechanism
- Uninterrupted gas runtime
- Minimal, basic maintenance required
Cons
- Grass bag fills frequently
- Lacks variable speed adjustment
- Standard noise level for gas
6. MightyMow 40V 21″ Self-Propelled – Best for Easy Use
The MightyMow makes effortless cordless mowing accessible and affordable, perfect for those prioritizing convenience and light weight.
It utilizes an exceptional dual 20V battery system (totaling 40V with 2 x 8.0Ah capacity) to provide an impressive up to 60 minutes of self-propelled runtime.
The variable self-propelled function adjusts speed from 2.0 to 4.3 ft/s, allowing users to move at a comfortable pace without physical exertion, which is ideal for older users. Its brushless motor provides strong suction for efficient clipping collection.
While performance dips in very wet or tall grass, the MightyMow is designed for routine maintenance on small to medium lawns where its long battery life and intuitive 6-position single-lever height adjustment shine brightest. It offers the most battery longevity for the money.
Best For: Individuals prioritizing outstanding runtime, affordability, and ease of maneuverability for small to medium, primarily dry lawns.
Key Specs:
| Battery Voltage | 2x20V (40V) |
|---|---|
| Battery Capacity | 2 x 8.0Ah |
| Speed Range | 2.0 to 4.3 ft/s |
| Height Range | 1″ to 3″ |
Pros
- Exceptional dual 8.0Ah battery runtime
- Variable self-propelled speed control
- Easy, lightweight maneuvering
- Highly competitive, low price point
- Quiet, low-vibration operation
Cons
- Less durable plastic housing
- Struggles in damp, tall grass
- Lower voltage limits raw torque
Self-Propelled Lawn Mower Buying Guide
Engine Type: Power Source Consideration
The core choice is gas versus electric. Gas models, like the BILT HARD 21″, offer high torque and unlimited runtime, ideal for large yards and tough grass, but require more maintenance.
Electric mowers, such as the Greenworks 80V, are favored for being quieter, eco-friendly, and requiring low maintenance. For yards under half an acre, the convenience of electric often outweighs gas power.
Drive System and Terrain Handling
For lawns featuring slopes or uneven ground, the drive system is vital. Rear-wheel drive is featured in models like the PowerSmart and Greenworks, providing superior traction as weight shifts backward when mowing uphill.
Additionally, variable speed control—present on the Greenworks 80V—allows you to perfectly match the mower’s pace to your walking speed and the lawn conditions.
Cutting Deck Features and Versatility
Look for versatility in cutting functions, such as the 4-in-1 systems found in the Greenworks models, which include mulching, bagging, side discharge, and even leaf pickup. A wide 21-inch cutting width covers more ground quickly.
For simplicity, choose a model with a single-lever height adjustment, like the BILT HARD or MightyMow, allowing quick, uniform changes to cutting height