---
title: "Solves Ohm's Law and the power equation given any two of four electrical quantities: voltage (V), current (I), resistance (R), and power (P). Uses V=IR, P=VI, P=I^2R, and P=V^2/R to derive the missing two values. Fundamental for every circuit design task: sizing resistors, estimating current draw, checking power dissipation, and verifying component ratings. Chain into led_resistor for LED circuits or voltage_divider for bias networks."
method: POST
path: "/api/ohms_law"
tags: ["pcb"]
---

# Solves Ohm's Law and the power equation given any two of four electrical quantities: voltage (V), current (I), resistance (R), and power (P). Uses V=IR, P=VI, P=I^2R, and P=V^2/R to derive the missing two values. Fundamental for every circuit design task: sizing resistors, estimating current draw, checking power dissipation, and verifying component ratings. Chain into led_resistor for LED circuits or voltage_divider for bias networks.

`POST /api/ohms_law`

## Request

- Base URL: `https://calc.engineer`
- URL: `https://calc.engineer/api/ohms_law`
- Auth: none declared

## Request body

- object
  - `voltage_v` number: Voltage in volts (V). Provide exactly 2 of the 4 parameters.
  - `current_a` number: Current in amps (A). Provide exactly 2 of the 4 parameters.
  - `resistance_ohm` number: Resistance in ohms. Provide exactly 2 of the 4 parameters.
  - `power_w` number: Power in watts (W). Provide exactly 2 of the 4 parameters.

## Response `200`

Computed result for ohms_law

- object
  - `result` object, required
    - `voltage_v` number, required: Voltage in volts (V).
    - `current_a` number, required: Current in amps (A).
    - `resistance_ohm` number, required: Resistance in ohms.
    - `power_w` number, required: Power in watts (W).
  - `tool` string, required
  - `version` string, required
  - `computed_at` string, date-time, required
  - `chain` object, required
    - `feeds` unknown[]
      - unknown
    - `accepts_from` unknown[]
      - unknown

## Other responses

- `400`: Validation error or invalid JSON
- `404`: Tool not found

---

[API](https://skmtc.dev/calc/apis/calc-engineer-api.md) · [All operations](https://skmtc.dev/calc/apis/calc-engineer-api/llms.txt) · [OpenAPI document](https://skmtc.dev/calc/apis/calc-engineer-api/revisions/8830480ec488?raw)