How do I read resistor color codes?

Four-band resistors: First two bands are digits, third is multiplier, fourth is tolerance. Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Gray=8, White=9. Example: Brown-Black-Red = 10 × 100 = 1000Ω = 1kΩ.

What determines a material's resistance?

R = ρL/A, where ρ is resistivity (material property), L is length, A is cross-sectional area. Longer wires have more resistance; thicker wires have less. Copper has low resistivity (good conductor); rubber has high resistivity (insulator).

Why do resistors heat up?

Power dissipation P = I²R = V²/R. The electrical energy lost to resistance converts to heat. A 100Ω resistor with 100mA flowing dissipates 1W as heat. Resistors are rated for maximum power—exceeding this causes overheating and failure.

What is a variable resistor (potentiometer)?

A potentiometer has three terminals with a sliding contact that varies resistance between terminals. Used for volume controls, dimmers, and position sensors. A rheostat is a two-terminal version that varies current. Values typically range from 1kΩ to 1MΩ.

Electric Resistance Converter

About Electrical Resistance Conversion

Electrical resistance measures how strongly a material opposes electric current flow. Higher resistance means less current flows for a given voltage. It's the electrical equivalent of friction. The fundamental relationship V = IR (Ohm's law) connects voltage, current, and resistance, enabling all circuit analysis. Resistance arises from collisions between moving electrons and atoms in the conductor. Materials with many free electrons (metals) have low resistance, while insulators impede electron flow with very high resistance.

The SI unit is the ohm (Ω), named after Georg Simon Ohm who discovered the proportional relationship between voltage and current. One ohm allows one ampere to flow when one volt is applied. Resistance converts electrical energy to heat (P = I²R), which is useful for heaters but problematic for power transmission. The temperature coefficient of resistance causes metals to increase resistance when heated and semiconductors to decrease, which temperature sensors exploit.

Our converter handles all standard resistance units from milliohms in power connections to gigaohms in insulation testing.

Common Electrical Resistance Conversions

From	To	Multiply By
Ω	kΩ	0.001
kΩ	Ω	1,000
Ω	MΩ	10⁻⁶
MΩ	Ω	10⁶
kΩ	MΩ	0.001
MΩ	kΩ	1,000
Ω	mΩ	1,000
mΩ	Ω	0.001
MΩ	GΩ	0.001
GΩ	MΩ	1,000

Electrical Resistance Unit Reference

Ohm (Ω) – The SI unit of electrical resistance, equal to one volt per ampere. Named after German physicist Georg Simon Ohm who published his law in 1827. The omega symbol (Ω) comes from the Greek alphabet. Standard resistor values span 0.1 Ω to 10 MΩ in E-series values (E12, E24, E96). Most circuit calculations naturally fall in the ohms-to-megohms range.

Kilohm (kΩ) – 1,000 Ω, the most common range for signal-level electronics. Voltage dividers, pull-up/pull-down resistors: 1-100 kΩ typical. Audio potentiometers: 10-500 kΩ. Input impedance of oscilloscopes: typically 1 MΩ (1000 kΩ). Resistor color codes easily span this range. Brown-black-orange = 10 kΩ.

Megohm (MΩ) – 1,000,000 Ω, the realm of high-impedance circuits and insulation. ESD protection resistors: 1-10 MΩ. Oscilloscope probe inputs: 10 MΩ. Human body resistance when dry: 0.1-1 MΩ. Insulation resistance testing starts at tens of megohms. Good insulation exceeds 100 MΩ. Poor insulation below 1 MΩ indicates failure risk.

Milliohm (mΩ) – 0.001 Ω, critical for power electronics and current sensing. Battery internal resistance: 1-100 mΩ. Current sense resistors: 1-100 mΩ. Connector contact resistance should be below 10 mΩ. At high currents, even milliohms cause significant power loss and heating: 100 A through 10 mΩ dissipates 100 W.

Gigohm (GΩ) – 10⁹ Ω, used in insulation testing and ultra-high-impedance applications. Good cable insulation: 10-100 GΩ per meter. Electrometer input resistance exceeds 100 GΩ. Measurements at this level require guarded connections and controlled humidity since surface contamination can provide parallel leakage paths.

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