# Voltage Divider Calculator

A voltage divider lets you convert an input voltage to a lower output voltage. For example a 5V input can be converted to a 3V3 output quite easily. The basic setup is made of two resistors:

But choosing the right resistors is quite tricky. You could take the formula and try some values in order to approximate the values or use the calculator formula:

 Input Voltage V Desired Output Voltage V

Possible resistor values for input voltage of 5V and output voltage of 3.3V, ordered by error:
R1 R2 Actual Error Power Disipation
330Ω 680Ω 3.366V 0.066V 0.025W
47Ω 100Ω 3.401V 0.101V 0.170W
47kΩ 100kΩ 3.401V 0.101V 0.000W
4.7kΩ 10kΩ 3.401V 0.101V 0.002W
470Ω 1kΩ 3.401V 0.101V 0.017W
4.7Ω 10Ω 3.401V 0.101V 1.701W
220Ω 470Ω 3.406V 0.106V 0.036W
22kΩ 47kΩ 3.406V 0.106V 0.000W
2.2kΩ 4.7kΩ 3.406V 0.106V 0.004W
10kΩ 22kΩ 3.438V 0.138V 0.001W
100Ω 220Ω 3.438V 0.138V 0.078W
1kΩ 2.2kΩ 3.438V 0.138V 0.008W
220Ω 330Ω 3.000V 0.300V 0.045W
2.2kΩ 3.3kΩ 3.000V 0.300V 0.005W

Please note: Don't use a voltage divider for high voltages, as the entire current has to pass the resistors, which will hurt them a lot. Alternatives are voltage regulators! And even more important: You shouldn't use low value resistors in real world voltage dividers. The power disipation column states how much energy is converted into heat and should be as low as possible.