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Voltage Divider Calculator

Science & Engineering

Vout=Vin·R2/(R1+R2), forward and reverse

Quick Answer

Voltage Divider Calculator: Vout=Vin·R2/(R1+R2), forward and reverse. Voltage Divider Calculator uses standard science & engineering formulas to compute accurate results instantly.

V
Ω
Ω
Ω
Solve for Vout
3.837 V

Calculation steps

  1. 1Unloaded: Vout = Vin × R2/(R1+R2)
  2. 2Vout = 12 × 4700/(10000+4700) = 3.837 V
Divider current0.82 mA
R1 power6.7 mW
R2 power3.1 mW

Design rules of thumb

RuleWhy
Load ≥ 10× R2 → droop < 10%Parallel combo stays close to R2
Divider current ≥ 10× load currentKeeps Vout stiff under load
Never power circuits from a dividerAny current draw collapses voltage; use a regulator
High R saves power but picks up noise1–100 kΩ is the usual sweet spot
A divider is perfect for reading sensors and scaling voltages into ADCs (e.g. 12 V battery into a 3.3 V microcontroller pin), but it is not a power supply: output impedance is R1||R2, so any load current shifts the voltage. Add an op-amp buffer or use a voltage regulator for power.

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How to Use

  1. Enter known quantities: fill values and confirm units in the Voltage Divider Calculator.
  2. Instant solution: unknowns solve live with the formula shown transparently.
  3. Use constant/material tables: standard physical constants and material data are listed on this page.
  4. Compare conditions: change inputs to compare scenarios.

Key Points

  • Voltage Divider Calculator is a free online science & engineering tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: Vout=Vin·R2/(R1+R2), forward and reverse.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Voltage Divider Calculator formula

Voltage Divider Calculator uses standard science & engineering formulas to compute accurate results instantly.

FAQ

How do I use the Voltage Divider Calculator?
Open the page and fill in the input fields — results update automatically. Vout=Vin·R2/(R1+R2), forward and reverse.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.

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Source & Updates

Based on CODATA recommended constants and standard physics formulas. Last updated: 2025-07

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. Voltage Divider Calculator[EB/OL]. https://www.yijiansuan.com/en/c/science/voltage-divider

Results provided by this tool are for reference only and do not constitute professional advice.