Dew heater designer

Enter nominal diameter of scope or lens (mm):
Enter actual outside diameter (mm):
Enter power supply voltage (volts):
Enter resistor power rating (watts):
Enter individual resistor value (ohms):
Enter chosen number of resistors:

Your results are as follows:
Design heater power = 7.24 watts
Design heater current = 0.60333333333333 amps
Design total heater resistance = 19.889502762431 ohms
Design number of resistors required = 20
Individual resistor power = 0.36923076923077 watts
Resistor spacing = 17.592918860103 mm
Actual heater power = 7.3846153846154 watts
Actual heater current = 0.61538461538462 amps
Actual total heater resistance = 19.5 ohms