What would be a reasonable voltage at the tip of a spark plug?

A reasonable voltage at the tip of a spark plug typically ranges from 12,000 to 45,000 volts, depending on the engine design and operating conditions. In high-performance engines, voltages can even exceed 50,000 volts to ensure reliable ignition of the air-fuel mixture. This high voltage is necessary to create a spark that can jump the gap between the electrodes in the spark plug, igniting the combustion process.