LED Resistor Calculator
LED Resistor Calculator lets you series resistance drops the supply-to-LED voltage difference at the target current. Enter your own values or load the worked example.
- Copy or download the computed result
- Adjust supply voltage
- See the processing method and limits
Method and calculation
Series resistance drops the supply-to-LED voltage difference at the target current.
Inputs and settings
LED Resistor Calculator accepts Supply voltage (minimum 0.000001); LED forward voltage (minimum 0.000001); Target current (mA) (minimum 0.000001).
Worked example
LED Resistor Calculator example — Supply voltage: 5; LED forward voltage: 2; Target current (mA): 20. Computed output: { "ohms": 150, "resistorWatts": 0.06 }
Output and limitations
LED Resistor Calculator: Use finite inputs. Results use double-precision arithmetic.
Technical references: JavaScript numerical operations
LED Resistor Calculator FAQs
LED Resistor Calculator applies the following rule to your input: Series resistance drops the supply-to-LED voltage difference at the target current. The worked example on this page uses the same processor as the result button.
LED Resistor Calculator has these boundaries: Use finite inputs. Results use double-precision arithmetic. Start by checking the supply voltage field against the units or format shown.
LED Resistor Calculator provides this sample: { "ohms": 150, "resistorWatts": 0.06 }. Use the sample button to reproduce it, then replace the inputs with your own values.