The amount of electricity a plugged-in microwave uses while not actively cooking or heating food is minimal. When the microwave is in standby mode or simply plugged in without running any cooking functions, it typically consumes a very small amount of power.
The power consumption of a microwave in standby mode can vary depending on the model and its energy efficiency. On average, microwaves in standby mode may use around 1 to 5 watts of electricity. However, keep in mind that this is a rough estimate, and the actual power consumption can vary from one microwave to another.
To put it into perspective, using 1 to 5 watts continuously for an entire day would amount to about 0.024 kWh to 0.12 kWh of electricity consumed. If you leave your microwave plugged in all year long in standby mode, it could use approximately 8.76 kWh to 43.8 kWh per year.
While the standby power consumption of a microwave is relatively low, it's still a good practice to unplug electrical devices when not in use for extended periods to reduce "phantom" or "vampire" power usage. This helps conserve energy and may lead to some cost savings over time. If unplugging the microwave between uses is inconvenient, you might consider using a power strip with an on/off switch to easily cut power to multiple devices at once when they are not needed.