What Size Generator Do You Need For Construction?

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The general sizes of generators you typically need for construction sizes are small (up to 5000 peak watts), medium (up to 12000 peak watts), and big (12000+ peak watts to much much more).

As you can expect, these are very rough estimations. Construction sites can vary immense amounts in power needs.

To get a somewhat better idea, you can look at the power need estimations of the construction site tools in the chart below and follow the steps after that.

However, you don’t want to take these numbers too seriously either.

Individual tool strengths and brands can still vary a lot in terms of the watts, amps, and volts they need.

In turn, the size of the construction site generator you need can definitely vary too.

To play it safe, you would want to figure out the exact power needs of your construction site(s) and choose a generator with that information.

Construction site wattage chart

To get a more precise idea of what size generator you need for your construction site you want to know what power consumption you can expect from your individual tools.

In the chart below, you can find some rough general guidelines for the wattage requirements you can expect according to websites like Honda, Lowes, Northern Tool, and Don Rowe.

Construction Site ToolRunning WattsAdditional
Starting Watts
Starting Watts
Air Compressor (1/2 HP)9756251600
Air Compressor (1 HP)140036005000
Airless Paint Sprayer60012001800
Angle Grinder900900
Battery Charger (15 amp)500200700
Band Saw12001200
Belt Sander (3″)120024003600
Bench Grinder (8″)140011002500
Circular Saw (7.25″)140023003700
Coffee Maker600600
Concrete Vibrator (1 HP)10801080
Concrete Vibrator (3 HP)24002400
Disc Sander12001200
Electric Drill (3/8″)440160600
Electric Drill (1/2″)600300900
Fan Duty (1/4 HP)6505501200
Halogen Lights9090
Hammer Drill7003001000
Heat Gun15001500
Impact Driver500500
Impact Wrench700700
Jack Hammer12601260
Jig Saw700700
Miter Saw180033005100
Multi Tool400400
Orbital Sander500500
Quartz Halogen Work Light
(1000 Watt)
Radial Arm Saw100010002000
Rebar Cutter24002400
Reciprocating Saw12008002000
Rotary Hammer (15 amp)18001800
Sump Pump (1/3 HP)8005001300
Sump Pump (1/2 HP)105011002150
Table Saw (10″)200020004000
Wall Chaser20002000
Wood Router16501650
Construction site wattage chart

Keep in mind that individual brands and sizes often vary in power needs.

The numbers above are often leaning toward the stronger models since a construction site is more serious than a DIY session.

Additionally, this chart does not include amp or volt requirements (although portable generators often take care of these).

When in doubt, you want to check with your favorite brands or retailers about the power needs.

What size generator do you need for construction work?

You typically need at least a 5000 peak watt generator for construction work but often even bigger generators are necessary too.

With the wattage chart above, some extra research, and a few steps, you can find out what size generator you need for your construction work projects.

  1. Note down your construction site tools and find out the most watt-intensive combination that will run at the same time.
  2. Count up the running watts of these devices and add at least a 10% safety margin. Your generator will need at least this many continuous watts.
  3. Add the highest amount of additional starting watts and add at least a 10% safety margin to this number. Your generator will need at least this many peak watts.

In theory, you can replace step 3 with a thought process where you turn on your tools in the “optimal” way in terms of the biggest starting watts first.

This could potentially make it so you can work with a smaller generator.

That being said, the bigger your construction site, the harder it becomes to coordinate this optimal start sequence.

In turn, the extra power safety margin is likely not a bad idea.

What kind of generator do you need for a construction site?

You typically just need a non-inverter generator that can run on gasoline, diesel, or propane for your construction site.

However, inverter generators or other low THD generators may be necessary if you want to safely power electronics like a laptop, printer, and coffee machine.

On the flip side, many construction site tools can run on high THD power too.

This can save you some money since high THD portable generators tend to be more budget-friendly.

When it comes to portable generator fuel types, your main options are gasoline, dual fuel (propane too), and tri fuel (propane and natural gas too).

There are also bigger diesel generators if these align with your construction site needs and guidelines.

Your choice of fuel type for your construction site generator will depend on safety guidelines, your location, and your preferences.

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Mats is the founder and head editor of Generator Decision. With a combination of critical thinking, tireless research, and a healthy interest in electronics he helps people find the right generators and how to use these. At this point in the journey, Mats has done research on hundreds of portable generators.