About

In fields like semiconductor manufacturing, microbiology, and precision engineering, the difference between a micrometer (um, μm, or micron) and a millimeter (mm) represents a massive scale shift. Micrometers are used to measure cells, bacteria, and CPU transistor gates, while millimeters are the standard for visible mechanical parts.

One millimeter contains 1,000 micrometers. This tool is built to handle the high-precision decimal values often found in these industries without introducing floating-point rounding errors. It accepts inputs with special characters like the Greek letter mu (μ), making it easy to paste data directly from technical datasheets or microscope software.

Formulas

The conversion from the microscopic scale to the macroscopic metric scale involves dividing by one thousand.

L_mm = L_μm1000

This is derived from the SI definitions:

1 mm = 10^-3 m
1 μm = 10^-6 m

Reference Data

Object	Micrometers (μm)	Millimeters (mm)
E. coli bacterium (length)	2.0 μm	0.002 mm
Red Blood Cell	7.0 μm	0.007 mm
White Blood Cell	25.0 μm	0.025 mm
Human Hair (thickness)	70.0 μm	0.07 mm
Sheet of Paper	100.0 μm	0.1 mm
Grain of Sand	500.0 μm	0.5 mm
Frog Egg	1,000 μm	1.0 mm
Computer Processor Transistor	0.005 μm (5nm)	0.000005 mm

Frequently Asked Questions

Yes. "Micron" is the older, common name for the micrometer. The symbol µm is used for both. In industry, you will often hear "10 microns" instead of "10 micrometers".

The converter preserves decimal precision up to 10 digits, which is crucial when working with nanometer-scale technologies converted to millimeters.

Yes. If you paste "150µm" or "150 um", the tool will strip the letters and convert the number "150" correctly.

The naked human eye can resolve objects down to approximately 40-50 µm (0.04-0.05 mm). Anything smaller requires a microscope.