The right way to size a subpanel for a basement shop is to start with the load, not the panel size itself. Think about what you actually plan to run at the same time: lighting, receptacles, dust collection, a table saw, a compressor, a heater, or a welder if that applies. A shop can look small on paper but still need a surprising amount of power once you add up tools with motors and anything that makes heat.
A practical approach is to list the biggest loads and estimate their current draw from the nameplates. A 120-volt tool that draws 12 amps uses less than a 240-volt heater or saw, but the startup surge on motors matters too. If you know you’ll only ever run one big machine at a time, you may not need a huge subpanel. If you want room to grow, oversizing the panel itself a bit is often smarter than installing a panel that is already full. The real limit is usually the feeder and the service capacity, not just the box on the wall.
For many basement shops, a 60-amp subpanel is enough for lights, several general-purpose circuits, and a moderate tool setup. A 100-amp subpanel gives more breathing room and is often a better long-term choice if you expect heavier tools, electric heat, or future expansion. What matters most is matching the feeder breaker, feeder wire size, and panel rating as a complete system. A 100-amp subpanel does not mean you are actually using 100 amps all the time; it just means the equipment is capable of supplying that amount safely if the feeder is sized for it.
Also pay attention to how you distribute the circuits. It is better to split shop loads into separate circuits for lighting, receptacles, and dedicated machines rather than trying to do everything on one or two circuits. That way a tripped breaker does not shut down the whole shop. If you have tools with high startup current, a dedicated 240-volt circuit for each major machine is usually the cleanest setup.
One detail people miss is the subpanel layout itself. In a subpanel, neutral and ground need to be kept separate. The neutral bar must be isolated from the panel cabinet, and the grounding bar must be bonded to the enclosure only if it is the service equipment, which a subpanel is not. That is a common wiring mistake and can cause nuisance issues or safety problems.
If you are unsure, a licensed electrician can help you do a load calculation and confirm what your main panel can support. That step is especially important if your basement shop will include a heater, compressor, or welding equipment, because those can change the sizing decision quickly.
