{"uid":"cap_pae2AF8mnQE2_w5-1KApg","slug":"led-series-resistor-calculator-79a3ed7e","name":"LED Series Resistor Calculator","description":"Series resistor for an LED from supply voltage, forward voltage and current, with nearest E12 and E24 values and real current.","url":"https://electronics-calc.x402tookit.com/led-resistor?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["supplyV","forwardV","currentMa"],"properties":{"count":{"type":"integer","description":"LEDs in series (default 1)"},"supplyV":{"type":"number","description":"Supply volts"},"forwardV":{"type":"number","description":"LED forward voltage (red about 2.0, white and blue about 3.0-3.4)"},"currentMa":{"type":"number","description":"Desired LED current in mA"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"e12":{"type":["null","object"],"properties":{"above":{"type":["null","number"]},"below":{"type":["null","number"]},"closest":{"type":["null","number"]}}},"e24":{"type":["null","object"],"properties":{"above":{"type":["null","number"]},"below":{"type":["null","number"]},"closest":{"type":["null","number"]}}},"asOf":{"type":["null","string"]},"source":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"disclaimer":{"type":["null","string"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"recommended":{"type":["null","object"],"properties":{"ohms":{"type":["null","number"]},"series":{"type":["null","string"]},"actualCurrentMa":{"type":["null","number"]},"resistorPowerMw":{"type":["null","number"]}}},"exactPowerMw":{"type":["null","number"]},"ledsInSeries":{"type":["null","number"]},"resistanceOhm":{"type":["null","number"]},"voltageAcrossResistorV":{"type":["null","number"]}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_1-BxrHlHW_FYYPqE2dWQv","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Calculates the required series resistor for an LED given supply voltage, LED forward voltage, and desired current, returning exact resistance, nearest E12/E24 standard values, and actual current with that resistor.","exampleAgentPrompt":"I'm wiring a white LED to a 5V supply — the LED has a forward voltage of 3.2V and I want 20mA through it. What series resistor do I need, and what's the closest E12 and E24 standard value?","exampleUseCases":[{"title":"Arduino LED wiring resistor","prompt":"I'm hooking up a red LED to my Arduino's 5V pin. The LED forward voltage is about 2.0V and I want 15mA current. What series resistor should I use, and what standard E12 or E24 value is closest?"},{"title":"12V panel indicator LED","prompt":"I need to drive a blue LED from a 12V supply — forward voltage is 3.3V and I want 20mA. What resistor do I need and how much power will it dissipate?"},{"title":"Series LED string resistor","prompt":"I'm putting 3 white LEDs in series on a 12V supply. Each LED has a 3.1V forward drop and I want 10mA through them. Calculate the resistor I need and the nearest E24 standard value."}],"resultDescription":"Returns the exact calculated resistance in ohms, the voltage across the resistor, the nearest E12 and E24 standard resistor values (closest, above, and below), the actual LED current that would flow with the recommended standard resistor, and the power dissipated in the resistor in milliwatts, plus a human-readable summary and recommendation.","failureModes":["Missing required query parameters (supplyV, forwardV, currentMa) returns an error","Supply voltage less than or equal to forward voltage makes calculation impossible (zero or negative resistor)","Unrealistically high current values may return degraded or warned responses","Non-numeric parameter values cause validation errors","Requesting more LEDs in series than the supply voltage can support"],"whenToPreferThis":"Use this endpoint when you need a quick, authoritative LED series resistor calculation that also returns nearest real-world standard E12/E24 resistor values and actual resulting current — saving the extra step of looking up standard values manually. Ideal for electronics design agents, hardware prototyping assistants, or hobbyist tools. Prefer over generic Ohm's law calculators when you specifically need standard resistor series rounding and power dissipation for LED circuits.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-26T00:35:19.763Z","isFirstParty":false,"canonicalSlug":"led-series-resistor-calculator-79a3ed7e"}