How many millimeter in 1 light-year? The answer is 9.4607304725808E+18. We assume you are converting between millimetre and light year. You can view more details on each measurement unit: millimeter or light-year The SI base unit for length is the metre. 1 metre is equal to 1000 millimeter, or 1.0570008340246E-16 light-year. Note that rounding errors may occur, so always check the results. Use this page to learn how to convert between millimetres and light years. Type in your own numbers in the form to convert the units!
You can do the reverse unit conversion from light-year to millimeter, or enter any two units below:
A millimetre (American spelling: millimeter, symbol mm) is one thousandth of a metre, which is the International System of Units (SI) base unit of length. The millimetre is part of a metric system. A corresponding unit of area is the square millimetre and a corresponding unit of volume is the cubic millimetre.
A light year, abbreviated ly, is the distance light travels in one year: roughly 9.46 × 1012 kilometres (9.46 petametres, or about 5.88 × 1012 (nearly six trillion) miles). More specifically, a light year is defined as the distance that a photon would travel, in free space and infinitely far away from any gravitational or magnetic fields, in one Julian year (365.25 days of 86400 seconds each).
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