LED Resistor Size Calculator

We are often asked what value resistor is needed when using a LED on a higher voltage. With this calculator, you can have a single or combination of LED's.


  LED Current Limiting Resistor Calculator  
  Maximum LED Forward Current   mA  
  Typical LED Forward Voltage Drop V  
  Supply Voltage     V  
  Number of LED's in Series (Chain)    
  Number of Chains in Parallel      
  Total Current Drawn     mA  
  Voltage Across Resistor   V  
  Resistor Value     Ohms  
  Power Disapated in Resistor   W  
  How to use LED Resistor Size Calculator  
  1. From the LED data sheet, identify the maximum LED current  
  (IF) or enter a lower value if desired  
  2. From the LED data sheet, identify the typical forward voltage  
  (VF) and enter this value    
  3. How many LED's do you have connected in series, enter this  
  number, minimum 1  
  4. How many chains of LED's do you have connected in  
  parallel, enter this number, minimum 1  
  5. Under results, the first two values are for info only. The third  
  value is the resistor value, you would normally choose the  
  nearest preferred value above this number.  
  6. The last result indicates the power dissipated in the resistor,  
  you need to make sure that the resistor chosen has a power  
  rating above this figure. Standard resistors are typically 0.25, 0.5  
  or 0.6W but power resistors above this are available such as 1W,  
  Disclaimer: Whilst we have taken evey care to ensure this calculator gives the correct answer, Technobots cannot be held responsible for any errors and their consequencies.