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Resistance divider calculator

Enter any three value calculations and click the Calculate button.

Vin = Input voltage
Vout =
The output voltage

Input voltageVin: V
TandemResistanceRa: Ω
Parallel resistance Rb: Ω
The output voltageVout: V

Resistance partial pressure calculation formula

Calculation formula of resistance shunt partial pressure total resistance

Let R1 and R2 be connected in parallel, and the current through them is I1 and I2.
U1=U2
I1*R1=I2*R2
I1/I2=R2/R1
I1/(I1+I2)=R2/(R1+R2) I2/(I1+I2)=R1/(R1+R2)
Let R1 and R2 be connected in series, and the voltages passing through them are U1 and U2.
I1=I2
U1/R1=U2/R2
U1/U2=R1/R2
U1/(U1+U2)=R1/(R1+R2) U2/(U1+U2)=R2/(R1+R2)

Resistance partial pressure formula

The so-called partial pressure formula is to calculate how the individual resistors in series divide the total voltage and how much voltage is divided.

The fractional voltage is calculated as: the percentage of the total resistance is the percentage of the divided voltage. The formula is: U = (R / R total) × U source

For example, the 5 ohm and 10 ohm resistors are connected in series in the middle of the 10V circuit, and 5 ohms account for 1/3 of the total resistance of 5+10=15 ohms, so the voltage of the ohm is also 1/3, that is
10/3 volts.

Voltage dividing circuit

When the ammeter is connected with its connected resistor, it has a partial voltage effect. At this time, it is externally connected (the current resistance of the ammeter is generally less than one ohm, but if the resistance connected to it is only a few ohms, the partial voltage effect is used), such as the connected resistor. If there are dozens of ohms or more, you can ignore the partial pressure effect of the ammeter and use the internal connection.

Resistance parallel total resistance

Two resistors in parallel
Parallel resistance =R1*R2/(R1+R2)
Total resistance after three or more resistors are connected in parallel
R=R1*R2*R3/(R1R2+R1*R3+R2*R3)