What Inverter Size Do I Need to Run Power Tools?

Power tools need well, a lot of power. So it should not come as a surprise that you must have a good sized inverter to run these. While some suggest using a generator for power tools, an inverter will work fine if it has enough power, and that is what we will show here.

A 4000 watt inverter can run several power tools like a jig saw, drill press and bench grinder. Routers and drills require 1500 watts to start up, but large table and circular saws may need up to 4000 watts to run effectively.

Calculate Inverter Size For Power Tools

The inverter size must be 30% to 50% larger than the surge watts required by the power tool. If a jig saw uses 900 watts on startup, the inverter has to be at least 1200 watts.

If you can get an inverter that is twice the size of the power tool startup/surge watts, that is even better. It might sound like too much, but remember that power tools -like any electronics – are subject to sudden power spikes.

If that happens it is best to have an inverter that can handle a lot of power like the Cantonape Pure Sine Wave 4000 . Never run an inverter to its stated limit. If your load is 1500 watts, the inverter has to have a few hundred watts in reserve.

To calculate an inverter for power tools:

Surge watts + 30% = inverter size

You can replace the 30% with 50% or any percentage. What is important is to give the inverter reserve power, not just for the surge watts but if you want to use other appliances or electronics.

The larger the inverter capacity, the more tools and devices you will be able to use. Your inverter may be able to run all the power tools you need, but what about other devices? If your workshop runs on inverter power, the lights will consume power too.

Include in your calculation everything that will run off the inverter. Not just the power tools but the lights, fan, appliances etc. This will give you a more accurate picture of what inverter size you will really need.

What are Surge Watts?

A surge watt refers to the power required by a power tool, refrigeratoror another device to start up. This is different from the running watts, which is the power being used as the device runs continuously.

A circular saw may require 3000 watts to start, but when it runs will use 1500 watts. The surge watts is only for a second, but your inverter must supply it otherwise the saw will not run.

Surge watts are usually double the running watts, but some instances it could be triple. Because there are so many different types of power tools, you have to check each one for the surge watt requirement, if applicable.

Inverter Size Guide For Power Tools

This guide is for the most commonly used power tools. These tools come in various sizes, so the power requirement for yours may be higher. Check the specs in your product to be certain. high end power tools may also have additional power requirements if you attach peripherals or other accessories.

Power Tool	Amps Draw Per Hour	Watts Per Hour	Inverter Size
Bench Grinder	2-6	250-800	1500W
Circular Saw 5 1/2	12-15	1500-3000	4000W
Drill Press	4-12	500-1500	2000W
Handheld Drill	3-5	300-500	1000W
Jigsaw	4-7	550-900	1500W
Orbital Disk Sander	3-5	360-500	1000W
Reciprocating Saw	4-12	500-1500	2000W
Router	6-12	720-1500	2000W
Small Angle Grinder	7-10	840-1200	2000W
Table Saw	15	2000-3000	4000W

Circular saws are also available in 7 1/2, and its startup watts is around 4500 watts. There are larger sizes for the other tools here as well, so make the proper adjustments in your calculations.

The inverter sizes in the chart assume you will only be using it to run the power tools. If you have a solar powered shed and it is connected to the system, you will need a bigger inverter.

If you have a 4000 watt inverter, you can run a circular saw and other power tools comfortably. As long as there is enough inverter power available to provide the surge watts, your power tools will run.

But if the inverter carries other loads like lights, a fan etc. the remaining power may not be enough for the surge watts. You have to calculate how many watts your inverter has left before loading your power tools.

How Long Can My Inverter Run Power Tools?

This is difficult to answer because people use power tools in different ways. Because they are used intermittently, we can only estimate the actual usage.

A 3000 inverter can run a 1000W jigsaw for 6 hours if the tool is used for 30 minutes in an hour. If you use the jigsaw for 15 minutes an hour, the runtime will be even longer.

Circular saw, bench grinders and other power tools can be compared to running a welder on solar power in that the watts per hour does not tell the real story. A router can use up to 1500 watts an hour, but only if it runs continuously for 60 minutes.

But most power tools are not used that way. Usually you turn on a table saw, cut some wood for a few minutes and turn it off. After a few minutes you cut another piece and so on. The same goes for other tools.

While the watt hour requirements are high, it is unlikely the demand would be reached. It could happen of course if you use different tools. You might start with a circular saw then a belt sander followed by a drill etc. In this case you can easily reach thousands of watts, but again it is unlikely the power tools will reach their maximum watt they are stated for.

Also keep in mind that surge watts are only for a second or even less. A circular saw with 3000 surge watts is not going to tie up the inverter. It just needs a second to startup and then it will only use 1500 watts max.

Compared to a refrigerator, motor or freezer, we cannot give an average of how long an inverter will last. This is because power tool usage differs widely from case to case. On one day you might use several tools to build a desk. On another you might only need a drill to make a small repair.

The most practical way to go about this is to get the largest inverter you can afford. Your inverter can never be too big for these tools. And if you find yourself with extra inverter power available you can always use it to run other appliances.

Pure Sine Wave or Modified Wave Inverter?

A pure sine wave inverter is recommended for power tools. It is more energy efficient than modified sine wave inverters and it does a better job of reducing energy loss. We suggest the heavy duty Giandel 4000 as it is one of the best pure sine wave inverters available.

Older modified sine wave inverters can generate energy losses up to 30%. Given the power demand of these tools, you need an inverter that is as effective as possible. If you have an energy efficient solar system, the inverter should be too.

Another reason to use pure sine wave is modern power tools may not even run on modified sine inverters. You might be able to make some of them work, but the tool will not produce optimum results. And forcing a table saw or any power tool to run on something it was not designed for could damage the equipment.

Do I Need Batteries to Run Power Tools on an Inverter?

An inverter in a grid tied system does not need a battery to run any appliance or tool. An off the grid system however, requires batteries to power the inverter.

A grid tied system means the inverter and solar panel system are connected to the company electrical grid. The grid functions as the battery, as that is where any excess solar power is stored. The inverter is connected to this system so you can use any power tool – or any electronic device – without using batteries.

An off the grid system is independent from any power utility. The house or RV generates its own power from a solar panel system, generator, batteries, wind turbine or another power source.

You can connect an inverter to a solar panel but you need a battery to run the inverter and your devices when the sun sets. The battery bank size will depend on how many power tools and appliances you want to run.

Because power tools require a lot of energy it is not practical to use them for extended periods running on batteries. If you have a large battery bank it will not be a problem. But if you use the system to run household appliances, it may not be enough. Invest in a powerful battery system to run power tools off the grid. If you want to use solar panels to run power tools, check out this guide.

Conclusion

Because power tools consume a lot of watts, some think it is impractical to use them on a solar inverter. But as shown here it is possible. If you can run a refrigerator or air conditioning system on an inverter, you can do the same with any power tool.