Electrical · Analog circuits
Voltage Divider Calculator
Size node voltages from Vin and a resistor ladder — drag ground between taps and watch the schematic light up as your values land.
Series resistors
R₁ at top (Vin side), Rₙ at bottom
Result
Node voltages
Vnode = Vin − I · ΣR
Enter Vin and two resistor values — the schematic updates as you type each field.
Series resistor ladders, node voltages, and ground reference — the models this calculator uses.
A voltage divider is one of the most fundamental circuits in electronics: resistors in series with taps taken at the junctions. Current is uniform through the chain, so each resistor drops a share of the input voltage proportional to its resistance.
For n resistors in series from Vin at the top:
- Total resistanceR_total = R₁ + R₂ + … + Rₙ
- Circuit currentI = V_in / R_total
- Node voltageV_i = V_in − I · (R₁ + … + R_i)
- Two-resistor tapV_out = V_in × R₂ / (R₁ + R₂)
Moving ground changes the reference — nodes above GND go positive, nodes below go negative. This calculator shows every node relative to your chosen ground position.
| Tap ratio | Example R₁, R₂ | Typical use |
|---|---|---|
| 50% | 10 kΩ, 10 kΩ | Half-scale reference, symmetric bias |
| 33% | 20 kΩ, 10 kΩ | 3.3 V logic from 5 V rail |
| 10% | 90 kΩ, 10 kΩ | ADC scaling, attenuation |
| 66% | 10 kΩ, 20 kΩ | Higher tap for comparator thresholds |
- Sensor interfacing — scaling outputs to ADC input ranges
- Biasing circuits — setting DC operating points in amplifiers
- Level shifting — converting between logic or supply voltages
- Potentiometers — variable dividers for controls and trim
- Reference voltages — stable taps from a single supply
- Multi-tap ladders — several outputs from one Vin
A load in parallel with the lower leg forms a new equivalent resistance and shifts the tap voltage. Keep Rload ≫ the Thevenin resistance at the node — typically 10× or more for <10% error.
- Power dissipation — each resistor carries I²R; size wattage accordingly
- Tolerance — 5% resistors limit accuracy; use matched pairs for precision references
- Temperature — resistance drift affects ratio stability over temperature
- Input impedance — high-Z dividers are sensitive to leakage and bias current
- Potentiometers are variable voltage dividers — your volume knob is one.
- Arduino analog inputs expect 0–3.3 V or 0–5 V — dividers scale sensor outputs safely.
- Op-amp bias networks often use three-resistor ladders for dual supplies.
- Thevenin resistance at the tap sets how much a load will disturb your output.
- 1% resistor tolerance directly limits divider accuracy — match pairs when it matters.
- At RF, parasitic capacitance turns your divider into a frequency-dependent attenuator.