Electric Resistance Converter
Convert electrical resistance between ohm, kiloohm, megohm, milliohm and microhm, volt per ampere, reciprocal siemens, the CGS units abohm and statohm, and the quantized Hall resistance. Pick two units, enter a value and read the result instantly.
Select two units to see the conversion factor.
This tool converts electrical resistance (Ω) only. It is not resistivity (Ω·m), not conductance (S) and not thermal resistance (K/W).
Electric Resistance Formula
Every resistance unit is a fixed multiple of the ohm. Result = value × (source factor ÷ target factor). Metric prefixes are exact powers of ten: 1 kΩ = 1,000 Ω, 1 MΩ = 1,000,000 Ω, 1 mΩ = 0.001 Ω and 1 µΩ = 0.000001 Ω. A volt per ampere and a reciprocal siemens are both exactly one ohm. The CGS units are exact too: 1 abohm = 10⁻⁹ Ω, and 1 statohm = c² × 10⁻⁵ Ω ≈ 8.98755 × 10¹¹ Ω, derived from the exact speed of light. The quantized Hall resistance is h/e² ≈ 25,812.807 Ω, from the exact SI values of h and e.
What Is Electrical Resistance?
Electrical resistance measures how strongly an object opposes the flow of electric current. It is defined by Ohm’s law, R = V ÷ I: the voltage across the object divided by the current through it. The SI unit is the ohm (Ω), the resistance that passes one ampere when one volt is applied. Resistance depends on the material and on the shape of the object: a longer or thinner wire has more resistance, and so does a hotter metal.
Resistances in practice run from the micro- and milliohms of busbars, shunts and contact joints, through the ohms of heaters and speakers and the kiloohms of resistors in electronic circuits, to megohms for insulation and high-impedance inputs. A 4.7 kΩ resistor is 4,700 Ω, an insulation reading of 500 MΩ is 5 × 10⁸ Ω and a 0.5 mΩ shunt is 0.0005 Ω. Insulation testers commonly read in megohms and gigohms, battery internal resistance in milliohms.
The volt per ampere and the reciprocal siemens (1/S) are just other ways to write the ohm. The abohm (the EMU of resistance) and the statohm (the ESU of resistance) are CGS units: the abohm is a billionth of an ohm, and the statohm is enormous, about 9 × 10¹¹ Ω. The quantized Hall resistance is a natural constant, h/e² ≈ 25.8 kΩ, the step size of the resistance in the quantum Hall effect, which is used to realise the ohm in standards laboratories.
Do not confuse resistance with related quantities. Resistivity is a property of a material in Ω·m, and resistance follows from it by R = ρ × L ÷ A (Electric Resistivity Converter). Conductance is the reciprocal, in siemens (Electric Conductance Converter). Thermal resistance in K/W is the heat-flow analogue and a different quantity (Thermal Resistance Converter).
Supported Units
This converter supports the following 12 resistance units. The last column gives the value of each unit in the base unit, the ohm. The volt per ampere and the reciprocal siemens equal the ohm. The abohm equals the EMU of resistance, and the statohm equals the ESU of resistance.
| Unit | Symbol | Value in Ω |
|---|---|---|
| Ohm | Ω | 1 |
| Kiloohm | kΩ | 1,000 |
| Milliohm | mΩ | 0.001 |
| Megohm | MΩ | 1,000,000 |
| Microhm | µΩ | 1e-6 |
| Volt per ampere | V/A | 1 |
| Reciprocal siemens | 1/S | 1 |
| Abohm | abΩ | 1e-9 |
| EMU of resistance | EMU | 1e-9 |
| Statohm | statΩ | 898,755,178,700 |
| ESU of resistance | ESU | 898,755,178,700 |
| Quantized Hall resistance | R_K | 25,812.80746 |
How to Use the Electric Resistance Converter
- Type the electric resistance in the value box. Decimals and scientific notation such as 0.0025 or 2.5e-3 are accepted.
- Choose the From unit and the To unit.
- The result appears instantly, or press Convert Now. Very large or very small results are shown in scientific notation.
- Use Swap Units to reverse the conversion, Copy Result to copy the answer, open Show this value in all units for a full list, and Clear to start again.
Step-by-step by hand
- Find the size of each unit in the common base unit (Ω): 1 kΩ = 1,000 Ω and 1 Ω = 1 Ω.
- Divide the source size by the target size to get the conversion factor: 1,000 ÷ 1 = 1,000, so 1 kΩ = 1,000 Ω.
- Multiply by your value: 4.7 kΩ × 1,000 = 4,700 Ω.
Resistance of ordinary conductors cannot be negative, so only zero and positive numbers are accepted.
Common Resistance Conversions
- Resistor value: 4.7 kΩ equals 4,700 Ω.
- Insulation test: 500 MΩ equals 500,000 kΩ and 500,000,000 Ω.
- Current shunt: 0.5 mΩ equals 500 µΩ.
- Battery internal resistance: 25 mΩ equals 0.025 Ω.
- Quantum Hall standard: 1 quantized Hall resistance equals 25.81280746 kΩ.
- CGS to SI: 1 abohm equals 1e-9 Ω, and 1 statohm equals 898,755,178,700 Ω.
Ohm to Other Resistance Units
Quick reference for frequently used values
| Ohm (Ω) | Milliohm (mΩ) | Kiloohm (kΩ) | Megohm (MΩ) |
|---|---|---|---|
| 0.001 | 1 | 1e-6 | 1e-9 |
| 0.1 | 100 | 0.0001 | 1e-7 |
| 1 | 1,000 | 0.001 | 1e-6 |
| 10 | 10,000 | 0.01 | 1e-5 |
| 100 | 100,000 | 0.1 | 0.0001 |
| 1,000 | 1,000,000 | 1 | 0.001 |
| 4,700 | 4,700,000 | 4.7 | 0.0047 |
| 100,000 | 100,000,000 | 100 | 0.1 |
| 1,000,000 | 1,000,000,000 | 1,000 | 1 |
Where and Why This Conversion Is Used
- Electronics: resistor values, pull-up and bias networks, input impedances.
- Power engineering: busbar and joint resistance in mΩ and µΩ, grounding and earth-fault values in ohms.
- Insulation and safety testing: megohm and gigohm readings from insulation testers.
- Batteries: cell internal resistance in milliohms.
- Metrology and physics: quantum Hall standards and CGS texts.
Limitations
- Resistance changes with temperature. A unit conversion does not correct for it.
- For AC circuits, impedance includes reactance as well as resistance. This tool converts units of resistance only.
Important Differences Between Related Electrical Measurements
- Resistance, Ω belongs to one particular object. Resistivity, Ω·m belongs to a material. For a uniform wire, R = ρ × L ÷ A, so the same copper has different resistance as a 1 m wire and a 100 m wire.
- Resistance vs conductance: conductance, in siemens, is 1 ÷ R. A 100 Ω resistor has a conductance of 0.01 S, or 10 mS.
- Electrical vs thermal resistance: ohms oppose current under a voltage. K/W opposes heat flow under a temperature difference. The names are alike and the quantities are not.
- Resistance vs impedance: impedance is the AC generalisation that adds capacitive and inductive reactance. At DC the two are the same.
Each converter on this site changes units within one quantity only, and none of them mixes quantities. The related tools are: Charge, Current, Linear Charge Density, Surface Charge Density, Volume Charge Density, Linear Current Density, Surface Current Density, Electric Field Strength, Electric Potential, Electric Resistance, Electric Resistivity, Electric Conductance, Electric Conductivity, Electrostatic Capacitance and Inductance.