It actually depends on your choice; different birdbaths are available with different amounts of wattage. If you live in extremely cold weather, you’ll need a powerful device. And for summer, spring, or warmer regions, you’ll require something moderate. For instance, when you ran when you run a 50-watt birdbath heater per day, you’ll have to spend 10 cents on it every day. However, you can also get a thermostatically controlled and energy-saving device to reduce your electricity bills.