What Size Generator Do You Need to Run a Bench Grinder?
By the Generator Size Calculator Team · Updated · 5 min read
Quick answer: Honda lists a bench grinder at 720 running and 1,000 starting watts for 6 inch, 1,400 and 2,500 for 8 inch and 1,600 and 3,600 for 10 inch. That points to a 2,000-watt inverter for a 6 inch grinder, 2,500 watts for 8 inch and 3,000 watts for 10 inch. The big wheels have a large start-up surge, so the starting watts decide the size.
Bench grinder watts by size
| Bench grinder | Running watts | Starting watts | Extra start-up surge |
|---|---|---|---|
| 6 inch | 720 | 1,000 | 280 |
| 8 inch | 1,400 | 2,500 | 1,100 |
| 10 inch | 1,600 | 3,600 | 2,000 |
These are Honda's typical figures. A grinder under load draws more than one spinning freely, so your label or a plug-in watt meter is the best check. See starting vs running watts for the difference.
Which generator size to choose
| Bench grinder | Generator for the grinder alone |
|---|---|
| 6 inch (720 / 1,000 W) | 2,000 W inverter |
| 8 inch (1,400 / 2,500 W) | 2,500 W |
| 10 inch (1,600 / 3,600 W) | 3,000 W |
Sizes keep the running load under 80% of the rating and assume a starting capacity about 25% above it. A typical 2,000-watt inverter gives about 1,600 running watts, which is too little for an 8 inch grinder at the 80% rule, so that one is better on a 2,500-watt generator. Compare with what size generator a workshop needs.
Example: grinder, lights and a radio
| Load | Running watts |
|---|---|
| Bench grinder, 8 inch | 1,400 |
| Work lights | 200 |
| Radio | 100 |
| Running total | 1,700 |
The grinder's start-up surge is 1,100 watts, so the peak is about 2,800 watts. A 3,000-watt generator carries 1,700 running watts under its 80% mark (2,400 watts), and its approximate 3,750-watt starting capacity covers the peak. The lights and radio are example values, so use your own.
List the grinder, a drill and lights to see the total.
Tips for a clean start
- Start the grinder first, with nothing else running, then add lights.
- Use a short, heavy cord. See the extension cord calculator.
- Do not stall the wheel. A heavy push raises the draw. Let the wheel do the work.
Run the generator outdoors, at least 20 feet from doors, windows and vents. Never in a garage or shed, even with the door open. Never run one inside a workshop. See how far a generator should be from your house.
Frequently asked questions
How many watts does a bench grinder use?
Honda lists an 8 inch bench grinder at 1,400 running and 2,500 starting watts. A 6 inch grinder is 720 and 1,000, and a 10 inch grinder is 1,600 and 3,600.
Can a 2000-watt generator run a bench grinder?
A 6 inch grinder, yes. An 8 inch grinder at 1,400 running watts is above the roughly 1,280-watt 80% mark of a typical 2,000-watt inverter, so a 2,500-watt generator is safer.
Can a 3500-watt generator run a 10 inch grinder?
Yes. A 10 inch grinder starts at 3,600 watts, which is within the roughly 4,400 starting watts of a 3,500-watt generator.
Why does a grinder need so many starting watts?
The motor has to spin a heavy wheel up to speed, so it draws a large current for a moment.
Can I run a grinder and a drill together?
Only if the generator covers both running loads plus the larger surge. Most people use one tool at a time.
Related calculators
Sources: Running and starting watts from the Honda generator wattage guide (bench grinders). Generator sizes apply the 80% running rule and an assumed starting capacity about 25% above the running rating. The lights and radio in the example are assumed values.