How many millimeters are in 1 AU?

One AU contains approximately 1.496 x 1014 mm (about 149.6 trillion).

Is this conversion practical?

In spacecraft engineering where instruments are aligned to millimeter precision at AU-scale distances. Mirror segments on space telescopes must be positioned to sub-millimeter accuracy while orbiting the Sun.

Millimeters to Astronomical Units (mm to au) Converter

Q: How many AU is 1 millimeter?

One millimeter equals approximately 6.685 x 10-15 AU.

1 mm = 6.68459 × 10⁻¹⁵ au

1 Millimeter equals 6.68459 × 10⁻¹⁵ Astronomical Units (1 mm = 6.68459 × 10⁻¹⁵ au). Convert Millimeters to Astronomical Units with formula, table, and examples.

One millimeter equals approximately 6.685 x 10^-15 astronomical units. The Earth-Sun distance (1 AU) is about 149.6 trillion millimeters. The millimeter measures engineering precision; the AU measures planetary orbits.

How to Convert Millimeters to Astronomical Units

au = mm ÷ 149,598,000,000,000

Divide the value in Millimeters by 149,598,000,000,000

Take your value in Millimeters
Divide by 149,598,000,000,000
Read the result in Astronomical Units

Common Millimeters to Astronomical Units Conversions

Millimeters (mm)	Astronomical Units (au)	Status
1 mm	6.68458 × 10⁻¹⁵ au
100 mm	6.68459 × 10⁻¹³ au
10,000 mm	6.68459 × 10⁻¹¹ au
1,000,000 mm	6.68459 × 10⁻⁹ au
100,000,000 mm	6.68459 × 10⁻⁷ au
10,000,000,000 mm	0.0001 au
1,000,000,000,000 mm	0.0067 au
100,000,000,000,000 mm	0.6685 au
1 × 10¹⁶ mm	66.8459 au

Good to Know About Millimeters to Astronomical Units Conversion

The JWST's primary mirror segments must be aligned to within 10 nanometers (0.00001 mm) while orbiting 1.5 million km from Earth (0.01 AU). This is the ultimate mm-to-AU challenge: nanometer precision at astronomical distance. Engineering does not get harder than this.

Millimeters to Astronomical Units: What You Need to Know

1 AU = 1.496 x 10¹⁴ mm (149.6 trillion). A 1 mm screw is 6.685 x 10^-15 AU. The James Webb Space Telescope orbits at about 1.5 million km (1.5 x 10¹² mm) from Earth, or about 0.01 AU. Its mirrors are aligned to millimeter precision at AU-scale distances.

What is a Millimeter? mm

A metric unit of length equal to one thousandth of a meter. Used in engineering, manufacturing, and precise measurements.

Metric engineering manufacturing rainfall

Learn more about Millimeter →

What is a Astronomical Unit? au

Exactly 149,597,870,700 meters by IAU 2012 definition. Roughly the average distance from the Earth to the Sun. Used for distances within our solar system.

Astronomical solar system distances astronomy planetary science

Learn more about Astronomical Unit →

Going the other way? Use our Astronomical Units to Millimeters converter.

Millimeters to Astronomical Units FAQ

One millimeter equals approximately 6.685 x 10^-15 AU.
One AU contains approximately 1.496 x 10¹⁴ mm (about 149.6 trillion).
In spacecraft engineering where instruments are aligned to millimeter precision at AU-scale distances. Mirror segments on space telescopes must be positioned to sub-millimeter accuracy while orbiting the Sun.

Non-Frequently Asked Questions About Millimeters to Astronomical Units

Questions nobody should ask - but someone did.

A typical M6x20 screw is 20 mm long. The Sun is 1.496 x 10¹⁴ mm away. That is 7.48 trillion screws. At $0.05 each, the screw highway costs $374 billion - roughly the GDP of Denmark. Danish screws to the Sun.
The Mars rovers land within about 20 km of their target after traveling 225 million km (1.5 AU). That is 20,000,000 mm accuracy over 2.25 x 10¹⁴ mm of travel - precision of about 1 part in 11 million. Your GPS is accurate to about 3 m (3,000 mm). NASA is better.
Neptune orbits at about 30 AU. If that were a 30 cm clock, 1 AU = 1 cm and 1 mm = 0.1 AU = about 15 million km. On a solar-system clock, 1 mm represents 15 million kilometers. That is roughly 39 Moon distances per millimeter. Astronomical clocks do not tick in human-readable increments.