Resistance Converter
Convert between different units of electrical resistance measurement including ohms, kilohms, megohms, abohms, statohms, and more. Essential for electrical engineering and electronics applications.
Conversion Settings
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Conversion Result
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Enter a value — the conversion updates as you type
Common Resistance Conversions
⚡ Resistance Fundamentals
Definition: Opposition to direct current flow; 1 Ω = 1 V/A
Conductance: Reciprocal of resistance (G = 1/R, measured in siemens)
Temperature Effect: Most materials' resistance changes with temperature (copper ≈ +0.39 %/°C)
AC vs DC: Impedance (Z) includes reactance for AC circuits and is also measured in ohms
Resistivity vs Resistance: ρ is a material property in Ω·m; R = ρL/A is the property of a specific part
🔬 Resistance by Application
🎯 Resistor Standards & Tolerances
Preferred Values: E12 series (±10 %, 12 values per decade), E24 series (±5 %, 24 values per decade)
Power Ratings: 1/4 W, 1/2 W, 1 W and 2 W are common for through-hole parts
Tolerance: ±1 %, ±5 % and ±10 % are typical for general-purpose parts, and dominate the real error budget
Temperature Coefficient: Usually specified in ppm/°C — 100 ppm/°C over 50 °C is a 0.5 % shift
🧮 Exact Factors Used by This Converter
SI prefixes: pΩ, nΩ, μΩ, mΩ, Ω, kΩ, MΩ, GΩ, TΩ — powers of ten, exact
Abohm (CGS-EMU): 1 abΩ = 10⁻⁹ Ω exactly, so 1 abΩ and 1 nΩ are the same resistance
Statohm (CGS-ESU, also written s/cm): 1 statΩ = 8.987551787368176 × 10¹¹ Ω
Not included: Wb/A (that is the henry) and resistivity units such as Ω·m, Ω·cm and mm²·Ω/m — different dimensions, so there is no conversion factor to the ohm
🔬 Quantum & Special Resistances
von Klitzing constant: R_K = h/e² = 25,812.80745… Ω — exact since the 2019 SI redefinition fixed h and e
R_K-90: 25,812.807 Ω exactly — the conventional value used from 1990 until 2019; quote it when reading older data
Quantum Hall effect: Hall resistance plateaus at R_K/i for integer i, which is how the ohm is realised in national metrology labs
Impedance of free space: Z₀ = √(μ₀/ε₀) = μ₀c = 376.730313… Ω
Planck impedance: Z_P = Z₀/4π = 29.9792458… Ω — the Planck voltage divided by the Planck current, a different constant from Z₀
About Resistance Converter
A precise electrical resistance converter that handles accurate conversions between various resistance units including ohms, kilohms, megohms, and specialized units like abohms and statohms. This professional tool is designed for electrical engineering, electronics design, and scientific applications requiring exact resistance measurements.
Why use a Resistance Converter?
Critical for electrical engineers designing circuits, electronics technicians selecting resistors, and researchers measuring material properties. Accurate resistance conversions ensure proper component selection, prevent circuit malfunctions, and are essential for Ohm's law calculations and impedance matching in electrical systems.
Who is it for?
Essential for electrical engineers, electronics designers, circuit analysts, and students studying electrical engineering. Also valuable for physicists working with electrical measurements, quality control technicians testing components, and professionals in telecommunications and RF engineering.
How to use the tool
Select the source unit in the 'From' dropdown — SI-prefixed ohms (pΩ to TΩ), the CGS abohm and statohm, or a named constant such as R_K or Z₀
Choose the target unit in the 'To' dropdown
Type the resistance value in the input field; the conversion updates as you type, with no Convert button to press
Read the result in the target unit, with the same quantity restated in SI engineering notation (for example 5000000 Ω = 5 MΩ)
Check the note under the result for the exact factor each unit uses, so the number is traceable
Press Swap Units to reverse the direction — the converted value carries over so the physical quantity stays the same
Copy the plain number to the clipboard, or download a text summary of the conversion for your design notes
Frequently Asked Questions
How do I convert resistance units?
Pick the 'from' unit, pick the 'to' unit, and type a value — the result updates on every keystroke, with no Convert button. The converter shows the result twice: as a plain number in the unit you chose (5000000 Ω) and in SI engineering notation with the natural prefix (5 MΩ), so a 4.7 kΩ part never appears as 4.7e+3. Exponent notation is used only for magnitudes outside the picoohm-to-teraohm prefix range. Everything runs in your browser in JavaScript — nothing is sent to a server. Use Swap Units to reverse the direction while keeping the same physical resistance.
What resistance units does this converter support?
Nine SI-prefixed ohms — pΩ, nΩ, μΩ, mΩ, Ω, kΩ, MΩ, GΩ, TΩ — plus the two CGS units: the abohm (EMU, 1 abΩ = 10⁻⁹ Ω exactly) and the statohm (ESU, also written s/cm, 1 statΩ = 8.987551787 × 10¹¹ Ω). It also carries four named constants that really are resistances: the von Klitzing constant R_K = h/e², the pre-2019 conventional value R_K-90, the impedance of free space Z₀, and the Planck impedance Z_P. Synonyms of the ohm such as V/A, 1/S and s/F are deliberately left out, because converting them would be a self-conversion.
How accurate is the resistance conversion?
Every factor in the table is either exact by definition (the SI prefixes, the abohm, the statohm, R_K-90) or derived from the exact 2019 SI constants (R_K = h/e², Z₀ = 2α·R_K, Z_P = Z₀/4π). The arithmetic is IEEE-754 double precision, good to roughly 15–16 significant digits; the display rounds to 6 significant figures in engineering form and up to 12 in the plain number, which is far beyond what any physical measurement supports. There is no precision setting to adjust — in practice resistor tolerance (±1 %, ±5 %, ±10 %) and temperature coefficient dominate your error budget, not the conversion.
What's the formula to convert kilohms (kΩ) to ohms (Ω)?
Ω = kΩ × 1,000, so 4.7 kΩ = 4,700 Ω and 0.22 kΩ = 220 Ω. Going the other way, kΩ = Ω ÷ 1,000. Every other pair works the same way through the ohm: the tool multiplies by the source unit's factor to get ohms, then divides by the target unit's factor, so 1 statΩ → MΩ is 8.987551787 × 10¹¹ ÷ 10⁶ = 898,755.1787 MΩ. The factor for both units is shown under each result, so you can reproduce the arithmetic by hand or in a spreadsheet when you need to document it.
What's the key accuracy caveat for resistance conversion?
Resistance and resistivity are different quantities and cannot be converted into one another. The ohm measures a specific component or path; resistivity ρ is a material property in Ω·m, related by R = ρL/A for a uniform conductor of length L and cross-section A. Units such as Ω·m, Ω·cm, mm²·Ω/m and cmil·Ω/ft are resistivity, so they are not in this converter. Watch the weber per ampere too: Wb/A is the henry, the unit of inductance — use the inductance converter for that. Copper's resistivity is 1.68 × 10⁻⁸ Ω·m at 20 °C, or 16.8 nΩ·m.
What's a common real-world use case for resistance conversion?
Everyday electronics design: a datasheet specifies a 10 kΩ pull-up, a BOM lists 10000 Ω, and a simulation file wants 0.01 MΩ — the same part written three ways. Current-sense shunts are quoted in mΩ while the multimeter reads Ω; insulation and leakage tests come back in GΩ or TΩ; a meter's 10 MΩ input impedance decides whether it loads the node it measures. Metrology work adds the CGS and quantum units: older physics literature quotes abohms and statohms, and calibration reports reference R_K or R_K-90, all of which need to reach the ohm before they can be compared.
What resistance units are commonly confused?
Resistance versus impedance: resistance is the DC opposition to current, while impedance Z includes reactance and is complex-valued for AC — both are in ohms, but they are not interchangeable. The abohm and the nanoohm look like different units yet are exactly equal, because 1 abΩ = 10⁻⁹ Ω by construction of the CGS-EMU system. R_K and R_K-90 differ in the fifth decimal (25,812.80745… Ω against exactly 25,812.807 Ω) and must not be mixed in one calculation. And the Planck impedance Z_P ≈ 29.98 Ω is not the impedance of free space Z₀ ≈ 376.73 Ω — they differ by a factor of 4π.
How do I handle very large or very small resistance values?
Let the engineering notation do it: the tool picks the SI prefix that puts the mantissa between 1 and 1000, so you read 1.5 mΩ or 220 GΩ rather than counting zeros. Exponent form (1.5e+18 Ω) appears only outside the prefix table, above 10¹⁵ Ω or below 10⁻¹² Ω. Values large enough to overflow double precision are rejected with a message instead of printing Infinity. If you are working with conductance instead — 1/R, in siemens — the conductance converter is the reverse-facing tool, and 1 mS is exactly 1 kΩ.
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