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Resistor Ratio Calculator

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Resistor Ratio Calculator | E-Series Voltage Divider Tool
SER
TYPE
R
Please enter valid ratio.
RESULTS
Single

Series

Parallel

Input Parameters Specification

Resistor SeriesSelect E12, E24, E48 or E96 standard resistor values to search practical resistor combinations.
Ratio TypeChoose direct resistor ratio R1 / R2 or voltage divider mode for Vout / Vin resistor network design.
Desired RatioEnter the target ratio for precision divider selection, gain setting, sensor scaling or feedback network design.
Inverse OptionUse inverse mode when the required circuit ratio is easier to express as the reciprocal target value.

Practical Operational Examples

Voltage Divider Case

Ratio Type: Voltage Divider
Desired Ratio: 0.35
Series: E24
Use for Vin to Vout divider scaling.

Resistor Ratio Matching

Ratio Type: R1 / R2
Desired Ratio: 2.5
Series: E96
Find low-error standard resistor pairs.

Diagrams & Theory

A resistor ratio or voltage divider uses two resistors to convert input voltage into a predictable output voltage. E-series matching helps reduce ratio error using real-world resistor values.

Vin R1 R2 Vout

Formulas & Mathematical Logic

Direct resistor ratio: Ratio = R1 / R2
Voltage divider ratio: Vout / Vin = R2 / (R1 + R2)
Equivalent divider resistor ratio used by search: R1 / R2 = ratio / (1 - ratio)
Error percentage compares the selected standard resistor combination against the desired ratio.

The calculator searches standard E-series values and compares single resistor, series-pair and parallel-pair denominator combinations to reduce practical matching error.

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About this tool

Resistor Ratio Calculator is a free online calculator tool. Use it to get instant, accurate results for your electronics calculations.