Calculate the right generator size for your workshop. Select your tools, and we will factor in startup surge wattage to recommend the proper generator capacity.
Based on your tool selection, you need a generator with at least 5,000 running watts and 6,500 starting watts.
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Running watts (also called rated watts) is the continuous power a generator produces to keep equipment running. Starting watts (also called surge or peak watts) is the extra power needed for the first few seconds when a motor starts up. Motors with induction coils (table saws, compressors, etc.) can require 2-3x their running wattage to start. Your generator must handle the highest starting surge plus all other running loads.
Portable generators cost $400-$2,000, run on gasoline or propane, and can be moved to job sites. They require manual starting and fuel management. Standby generators cost $3,000-$15,000+ installed, connect permanently to natural gas or propane, and start automatically during outages. For most workshops, a quality portable generator in the 5,000-7,500W range offers the best balance of capability and value. Choose standby if you need whole-house backup or have frequent extended outages.
Gasoline is widely available and provides the most power, but degrades after 30 days without stabilizer and requires more maintenance. Propane stores indefinitely, burns cleaner, and requires less maintenance, but produces about 10-15% less power. Dual fuel generators let you use either fuel, offering flexibility - run on gas for maximum power, switch to propane for storage or cleaner operation. For workshop backup, dual fuel is often the best choice.
Inverter generators produce clean, stable power (under 3% THD) safe for sensitive electronics, run quieter (50-60 dB), are more fuel efficient at partial loads, and are typically lighter. However, they cost 2-3x more per watt. Conventional generators are louder (65-75 dB), less fuel efficient, but much more affordable and available in higher wattages. For a workshop, conventional generators work fine for most power tools. Choose inverter if you need to run CNC machines, computers, or sensitive electronics, or if noise is a concern.
The safest method is using a transfer switch installed by a licensed electrician. This prevents backfeeding power to utility lines (which can injure workers). For portable use, run heavy-duty extension cords rated for your load directly from the generator to tools. Never plug a generator into a wall outlet. Always operate generators outdoors at least 20 feet from buildings, and use a carbon monoxide detector. For frequent use, consider a manual transfer switch ($200-$500 installed) or an interlock kit for your electrical panel.
Fuel consumption varies by load and generator efficiency. As a rough guide: a 5,000W generator uses about 0.5-0.75 gallons per hour at 50% load. Inverter generators are more efficient at partial loads. Most portable generators have 4-8 gallon tanks providing 8-12 hours of runtime at half load. For all-day workshop use, plan for 4-6 gallons per 8-hour day at moderate loads. Keep stabilized fuel on hand and never refuel while the generator is running or hot.