5V to 3.3V Voltage Divider (1kΩ / 2kΩ)
Compute the unloaded and loaded output of a two-resistor divider, plus the current and the power in each resistor.
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About this tool
This page opens the voltage divider calculator with a 5V input, a 1kΩ top resistor (R1) and a 2kΩ bottom resistor (R2) already filled in — the output voltage, current and power below are computed live on load.
5V-to-3.3V is the single most common voltage divider search, because it is the classic mismatch between a 5V logic device (many Arduino boards, older sensors) and a 3.3V input (most modern microcontrollers, SPI/I2C peripherals). With R1 = 1kΩ and R2 = 2kΩ, the ratio R2 / (R1 + R2) = 2000/3000 gives exactly 0.667, so 5V in becomes 3.33V out — close enough to 3.3V for most digital logic thresholds.
One caveat this exact pairing exists to teach: a resistive divider is fine for a steady logic-level signal into a high-impedance input (like a GPIO pin), but it is the wrong tool for anything that draws real current — for that, see the loaded-divider preset below, or use a proper regulator or level shifter instead.
Example. The defaults, 5 V with R1 and R2 at 10 kΩ and no load, report an ideal output of 2.5 V, a loaded output of 2.5 V, current 250 µA, and 625 µW in each resistor. A 10 kΩ load drops the loaded output to 1.6666666666667 V.
Limit. Vin, R1, and R2 must be positive. A non-positive load is ignored. Tolerance, source impedance, and AC impedance are not in the formula.