LED series-resistor calculator API

Size the current-limiting series resistor for an LED (R = (Vsupply − Vforward) / Iforward), snapping to the nearest E24 value and reporting resistor power. Answers 'what resistor for a 2V LED at 20mA on 5V','nearest standard resistor for my LED','what wattage resistor does the LED need'.

Price$0.01per request

MethodPOST

Route/v1/calc/eng-led-resistor

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

calcengineeringelectricalledresistorcurrent-limite24hardware

API URLhttps://x402.hexl.dev/v1/calc/eng-led-resistor

Integration docs

Example request

{
  "supplyV": 5,
  "forwardV": 2,
  "currentMa": 20
}

Example response

{
  "supplyV": 5,
  "forwardV": 2,
  "currentMa": 20,
  "resistanceOhm": 150,
  "nearestE24Ohm": 150,
  "resistorPowerW": 0.06,
  "formula": "R = (Vsupply - Vforward) / I"
}

Input schema

{
  "type": "object",
  "required": [
    "supplyV",
    "forwardV",
    "currentMa"
  ],
  "properties": {
    "supplyV": {
      "type": "number",
      "description": "supply volts",
      "examples": [
        5
      ]
    },
    "forwardV": {
      "type": "number",
      "description": "LED forward voltage",
      "examples": [
        2
      ]
    },
    "currentMa": {
      "type": "number",
      "description": "desired LED current (mA)",
      "examples": [
        20
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}