Voltage Converter

Your multimeter reads 1.42 V, the spec sheet calls for 1420 mV, and you have to write a report that uses kilovolts because the senior engineer prefers them. Same number, three places, three units. Type it once.

The three-way conversion (mV → V → kV) covers most electronics work — sensor outputs in millivolts, board power in volts, transmission and high-voltage gear in kilovolts. Each step is a clean factor of 1,000, so the math itself is trivial; the value is in not having to think about it twice.

No conversion to amps or watts here. Voltage alone doesn't tell you current or power without more information.

The relationship between the units is clean: 1 V = 1,000 mV; 1 kV = 1,000 V. That's it. Going from millivolts to kilovolts means dividing by a million, but you'll rarely make that jump in one step — typical electronics work bounces between mV and V, while transmission and power engineering bounces between V and kV.

A worked example: you're reading a thermocouple sensor that outputs about 41 microvolts per degree Celsius. At 25°C, that's roughly 1.025 mV — too small to feed directly into a microcontroller's ADC, which usually expects somewhere between 0 and 3.3 V. You'll amplify the signal first, often with a gain of around 100, putting the amplified output near 100 mV at room temperature. The conversion isn't just labeling; it's the bridge between sensor physics and signal-conditioning math.

Where this converter stops being useful: when you actually need to compute power or current. Voltage alone tells you potential difference, which doesn't tell you how much current flows or how much energy moves. For that you'd use Ohm's law (V = IR) and Watt's law (P = VI). A 5 V supply might deliver 1 A or 100 A depending on the load and the supply's current rating — same voltage, vastly different power.

A note on AC versus DC: the rated voltage of a wall outlet (120 V or 230 V depending on region) is the RMS value, which is roughly 0.707 of peak. So a '120 V' outlet actually swings between roughly +170 V and −170 V at 60 Hz. This matters when you're designing insulation, picking capacitor voltage ratings (always rate above peak, not RMS), or interpreting oscilloscope traces. The converter handles the magnitude relationships; the AC/DC interpretation is your responsibility.