Electric Resistance Converter

Electric Resistance Converter

Convert between ohms, kilohms, megohms, gigohms, milliohms, and microhms with this free tool. Resistance values in electrical work span more than 15 orders of magnitude — from the few milliohms of a bus bar connection to the gigohms of MOSFET gate insulation — and a unit mismatch at any point can mean the wrong component, a failed insulation test, or an inaccurate voltage drop calculation.

How Electric Resistance Conversion Works

The ohm (Ω) is the SI base unit of resistance, defined as the resistance that allows 1 ampere to flow under 1 volt of potential difference (from Ohm’s law: R = V / I). All resistance unit conversions are pure powers of ten:

result = input x (source factor in Ω) / (target factor in Ω)

Key factors:

• 1 milliohm (mΩ) = 0.001 Ω
• 1 microhm (μΩ) = 0.000001 Ω
• 1 kilohm (kΩ) = 1,000 Ω
• 1 megohm (MΩ) = 1,000,000 Ω
• 1 gigohm (GΩ) = 1,000,000,000 Ω

Worked Examples

Example 1 — Resistor value (kilohms to ohms) A circuit schematic calls for a 4.7 kΩ pull-up resistor. 4.7 x 1,000 = 4,700 Ω — used when searching a parts catalog that lists values in ohms.

Example 2 — Insulation test (megohms to gigohms) A motor winding tests at 850 MΩ with a Megger. 850 / 1,000 = 0.85 GΩ — useful when comparing to manufacturer specs listed in gigohms.

Example 3 — PCB trace resistance (milliohms to microhms) A 10 cm PCB trace measures 45 mΩ under four-wire testing. 45 x 1,000 = 45,000 μΩ — relevant when evaluating voltage drop in high-current power planes.

Electric Resistance Unit Reference Table

When to Use a Resistance Converter

• Converting resistor values from kilohms or megohms to ohms when entering values into Ohm’s law calculations
• Comparing insulation resistance test results (MΩ or GΩ) across different test equipment that may display in different units
• Translating wire resistance tables (often in Ω per 1,000 ft or mΩ/m) into circuit-level milliohm values
• Working with CGS-based physics references that use abohms alongside modern SI component specifications
• Verifying that contact resistance values in milliohms are within acceptable limits for connector or switch specifications

Common Mistakes

1. Misreading kΩ as Ω on a multimeter. A reading of 4.7 on the kΩ range is 4,700 Ω, not 4.7 Ω. Always confirm which range the meter is set to before recording a value.
2. Applying Ohm’s law with mixed units. R = V / I only works when resistance is in ohms, voltage in volts, and current in amperes. Converting to base SI units first prevents errors of several orders of magnitude.
3. Ignoring lead resistance in milliohm measurements. Standard two-wire measurements include the resistance of the test leads (typically 0.1-0.5 Ω). For values under 10 Ω, this is significant — use a four-wire (Kelvin) connection instead.
4. Assuming insulation resistance passes or fails at a fixed megohm number. The standard minimum is 1 MΩ per kV of rated voltage for motors. A 480 V motor needs at least 0.48 MΩ, while a 4,160 V motor needs at least 4.16 MΩ.

Quick Reference Benchmarks

Tips

• For resistor color codes, the multiplier band shortcut: red = x100 (ends in two zeros), orange = x1 kΩ, yellow = x10 kΩ — match this directly to your target unit.
• When calculating voltage drop across a wire run, look up the resistance in mΩ/ft from an AWG table, convert to ohms, then apply V = I x R.
• Insulation resistance degrades with temperature and moisture — always record the temperature when logging Megger test results for meaningful trend analysis.
• Resistors in the E12 and E24 series follow preferred value sequences in each decade (decade here means a x10 step); knowing 4.7 kΩ and 47 kΩ are both standard helps when scaling designs.
• For parallel resistance, convert all values to the same unit (ohms) before applying 1/R_total = 1/R1 + 1/R2; mixing kilohms and ohms in the formula without converting first is a common error.
• In high-frequency circuits, PCB trace resistance matters less than trace inductance — but for DC and low-frequency power delivery, even a few milliohms at 10+ A creates measurable voltage drop.