Short Answer: Buy corded if you grind metal for more than 30 minutes at a stretch, do production welding, or want the most power for the least money. Buy cordless if you use a grinder intermittently, work on jobsites without power, or value the convenience of no cord. In 2026, cordless grinders have enough power for most tasks — the remaining advantage of corded is unlimited runtime.
Head-to-Head Comparison
| Factor | Corded | Cordless | Winner |
|---|---|---|---|
| Peak Power | 11-15 amps (continuous) | Comparable peak, lower sustained | Corded |
| Runtime | Unlimited | 10-30 min (grinding) | Corded |
| Portability | Needs outlet + cord | Go anywhere | Cordless |
| Weight | 4-6 lbs | 4-7 lbs (with battery) | Corded |
| Safety Features | Basic | E-brake, anti-kickback, drop detect | Cordless |
| Cost (tool only) | Check current | Check current | Corded |
| RPM (4.5" models) | 10,000-11,000 | 8,500-9,000 | Corded |
| No-cord hazard | Trip/cut risk | No cord | Cordless |
Power: Corded Still Wins (Barely)
A typical corded 4.5-inch angle grinder draws 11 amps continuously — that is about 1,300 watts of sustained power. A cordless 18V grinder on a 6.0 Ah battery can match that wattage in short bursts, but the battery chemistry limits sustained output. Under continuous heavy grinding, the cordless tool manages about 80-90% of the corded tool's cutting speed. For most tasks — grinding welds, cutting rebar, removing rust, shaping metal — you will not notice the difference. The gap becomes apparent during extended heavy grinding on thick steel plate or continuous cutting of material with a cut-off wheel. If you are grinding for 30+ minutes straight, the corded tool maintains a consistent cutting speed that the cordless tool gradually loses as the battery discharges. The exception is 36V cordless grinders (like the DeWalt FLEXVOLT or Metabo HPT MultiVolt). These match or exceed corded power output in every measurable way. But they carry premium bare-tool prices and require expensive high-capacity batteries.Runtime: The Real Difference
This is where corded grinders have an undeniable advantage. Plug in a corded grinder and it runs until you unplug it. A cordless grinder on a 5.0 Ah battery gives you approximately:- Light grinding (paint removal, rust): 20-30 minutes
- Moderate grinding (weld cleanup): 12-20 minutes
- Heavy grinding (cutting, thick stock): 8-15 minutes
Safety: Cordless Wins
Modern cordless grinders include safety features that most corded grinders lack: Electronic brake. Stops the disc in under 2 seconds when you release the trigger. Corded grinders coast for 5-10 seconds. A spinning disc on a tool you just set down is a hazard. Anti-kickback clutch. If the disc binds, the clutch disengages the motor to prevent the tool from wrenching out of your hands. Some corded grinders have mechanical slip clutches, but the electronic versions on cordless tools respond faster. Drop detection. Some cordless models (Milwaukee, DeWalt) detect if the tool is dropped and shut off the motor instantly. This prevents a running disc from bouncing across the floor. No cord. This might be the biggest safety advantage. A cord running across a work area while you operate a spinning disc is a genuine hazard — tripping, snagging, and accidental cutting of the cord are all real risks.Cost: A Closer Look
The upfront cost comparison is misleading if you only look at tool prices. Corded scenario: a good corded grinder (DeWalt DWE402, Makita GA4530) is the cheapest route. Plug it in and grind. There is nothing else to buy. Cordless scenario (already own batteries): $100-180 for a bare tool. If you are on the Milwaukee M18 or DeWalt 20V MAX platform and already have batteries, the total cost is just the bare tool. Cordless scenario (starting from scratch): $180-300 for a kit with battery and charger. If you do not own any batteries, the entry cost is significantly higher — and you are locked into that battery platform for future tools. The long-term cost of cordless also includes battery replacement. Lithium-ion batteries degrade over 3-5 years of regular use. A corded grinder from 2010 still runs the same as the day you bought it.Use Case Recommendations
Buy Corded If You:
- Grind or cut metal for 30+ minutes continuously
- Do production welding and need to clean welds all day
- Want the most power for the lowest cost
- Work in a shop with outlets nearby
- Do not already own a cordless battery platform
Buy Cordless If You:
- Work on jobsites, farms, or locations without power
- Use a grinder intermittently (a few minutes at a time)
- Already own batteries on a major platform (Milwaukee, DeWalt, Makita)
- Value modern safety features (e-brake, anti-kickback)
- Cut pipe or rebar at various locations
Buy Both If You:
- Do metalwork seriously — a corded grinder for bench work and a cordless for field work
- This is the most common setup in professional fabrication shops
