Series / Parallel Resistor Calculator

The first two calculators below calculate series or parallel combinations of resistors. Enter the resistor value and press 'Add to Total'. Repeat until all resistors have been entered. Press 'Clear Total' to start a new calculation. The third calculator will find a resistor value to place in parallel with a given resistor value to produce a specified total. Preferred resistor values are also calculated, use the radio buttons on each calculator to select the preferred value series to use.

Resistors in Series - Calculate Total:

Enter resistance, press 'Calculate R' to add to total. Press 'Clear Total' to reset.        Ohms Kilohms Megohms				Total R = ? Preferred Total R = ?
Select preferred series (optional): E12    E24    E48 E96    E192

Resistors in Parallel - Calculate Total:

Enter resistance, press 'Calculate R' to add to total. Press 'Clear Total' to reset.        Ohms Kilohms Megohms				Total R = ? Preferred Total R = ?
Select preferred series (optional): E12    E24    E48 E96    E192

2 Resistors in Parallel - Calculate One Resistor from Other and Total:

Enter R1 and the total resistance to calculate the value of the other resistor needed to produce the required total. R1:        Ohms Kilohms Megohms Total R: Ohms Kilohms Megohms		R2 = ? Preferred Total R = ?
Select preferred series (optional): E12    E24    E48    E96    E192

Formulae

Resistors in series:

R_TOTAL = R₁ + R₂ + R₃ + ...

Resistors in parallel:

1 / R_TOTAL = (1 / R₁) + (1 / R₂) + (1 / R₃) + ...