Ohm's Law Calculator

Use the Ohm’s-law head tool for V/I/R/P relationships, then move to resistor networks, divider, reactance or filter tools when the circuit model changes.

Voltage

Current

Resistance

Power

Enter any two known valuesV = IR · P = VI

—Voltage

—Current

—Resistance

—Power

For a simple resistive relationship. Real devices may be non-ohmic, temperature dependent, or frequency dependent.

Educational / low-voltage electronics calculator. Real components have tolerances and non-ideal behavior. Do not use this page as a substitute for qualified design or safety guidance for mains/high-energy electrical systems.

Electrical model check

Verify the circuit relation, units, and result

ideal lumped low-voltage relationship

V = IR · P = VI = I²R = V²/R

Reading the current calculator inputs…

Use two compatible known quantities; component limits and temperature are separate.

Low-voltage educational scope. This review does not provide mains wiring, live-work, conductor-sizing, protection-device, or safety-certification instructions.

Electrical uncertainty cluster

Calculate the nominal circuit, then expose what input spread can change

Nominal equations are only the center point. Use component tolerances and measurement uncertainty to inspect a min/base/max operating envelope, then verify real component ratings and datasheets separately.

Ohm's Law SMD resistor codes Battery runtime

All 24 electrical tools

LED ResistorSupply, Vf and resistor spread → current envelope mAh → WhBattery rating spread → energy envelope Voltage DropCurrent, run and conductor spread → delivered voltage Voltage DividerVin and resistor spread → output envelope Capacitor NetworkPart tolerance → equivalent-capacitance sensitivity Resistor BandsDecoded tolerance → current and power consequences Parallel ResistorsBranch tolerance → Req/current/power envelope W / V / AKnown-input spread → solved-value envelope

Match the calculator to the circuit model

Ohm’s law, dividers, RC/RL timing, reactance and battery estimates answer different questions. Keep units and assumptions visible instead of combining unrelated quantities.

Low-voltage educational scope

WebToolArc does not certify wiring, component safety, mains installations or high-energy systems. Use component datasheets and qualified guidance where safety matters.

Governing electrical relation

V = IR · P = VI = I²R = V²/R — ideal lumped low-voltage relationship.

How to cross-check the result

Substitute the solved quartet into V=IR and P=VI. Both identities should agree within rounding.

Real-component boundary

Use two compatible known quantities; component limits and temperature are separate. Component tolerance, temperature, parasitics, datasheet limits, installation rules, and hazardous-energy safety are not inferred by this idealized calculator.