Resistors Formulas
Resistor formulas cover how resistance combines in series and parallel and how to size current-limiting resistors for components such as LEDs. These calculators add, combine, and reverse-solve resistor networks so you can pick standard values quickly. They are essential for biasing, current limiting, and building precise resistance values from common parts.
Resistors Formula Calculators
- Series Resistance Rtotal = R1 + R2 + ... + Rn
- Parallel Resistance 1/Rtotal = 1/R1 + 1/R2 + ... + 1/Rn
- LED Resistor R = (Vs − Vled) / Iled
- Resistor Power Derating Pmax = Prated × (Tmax−Tamb)/(Tmax−Trated)
- Resistive Attenuator Atten = 20 × log10(R2 / (R1 + R2))
- Resistor Tolerance Range R_max = R × (1 + tol)
- Resistor Thermal Noise (Johnson–Nyquist) Vn = √(4 × k × T × R × BW)
- Potentiometer Output Vout = Vin × Rpos / Rtotal
- Delta-to-Wye (Δ→Y) Transform R_Y = (Ra × Rb) / (Ra + Rb + Rc)
- Nearest E24 Resistor Value Round to nearest standard E24 value
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