🌕 Earth to Moon Distance Calculator
Get center-to-center or surface-to-surface distance between Earth and the Moon in various units, with perigee/apogee range and to-scale comparisons.
Live Distance Calculator
384,400
Kilometers (km)
How It's Calculated
The calculation depends on the selected mode:
- Base Distance (km): We start with a base distance in kilometers depending on the mode (e.g., Average = 384,400 km).
- Unit Conversion: The base distance is then converted to your chosen unit using a standard formula. For example:
miles = km × 0.621371. - Light-Seconds: This is calculated by dividing the distance in km by the speed of light (299,792.458 km/s). Round-trip is simply double the one-way time.
How Scientists Measure the Earth-Moon Distance
Measuring the vast distance to the Moon has evolved over centuries, from simple geometry to hyper-accurate laser technology.
- Lunar Laser Ranging (LLR): This is the gold standard. Scientists from NASA and other international teams fire powerful laser pulses at special retro-reflectors placed on the Moon's surface by the Apollo and Lunokhod missions. By precisely timing the ~2.5 second round-trip of the light, they can measure the distance with millimeter to centimeter precision.
- Spacecraft Ephemerides: Data from lunar orbiters and probes allows agencies like NASA's Jet Propulsion Laboratory (JPL) to create highly accurate models (ephemerides) of the solar system. These models can predict the Moon's exact position at any given time.
- Historical Methods: Early methods included using parallax (observing the Moon from two different locations on Earth) and radar ranging (bouncing radio waves off the Moon).
User Guide
- Want a quick fact? Choose "Average" mode for the commonly cited mean distance of 384,400 km.
- Want the exact distance right now? Choose "Instantaneous". This simulates the real-time distance which varies minute by minute due to the Moon's elliptical orbit.
- For photography or "supermoon" info: Select "Extremes (Perigee)" to see the distance when the Moon appears largest in the sky.
- For classroom use: Use the "Print" button to create a "calculate the distance from Earth to Moon worksheet" based on your current selections.
FAQs
Q: How to calculate distance between Earth and Moon?
A: You can use the mean value of 384,400 km for simple answers. For precise, instantaneous values, scientists use an ephemeris (like JPL Horizons) or time a laser ping to and from lunar retro-reflectors (LLR).
Q: How to calculate distance from Earth to Moon in meters (scientific notation)?
A: You multiply the distance in kilometers by 1,000. For the average distance, this is 384,400,000 m, which is written as 3.844 × 10⁸ m in scientific notation. You can select this option in our calculator.
Q: What is the distance from moon to earth calculation method?
A: The most accurate modern method is Lunar Laser Ranging, where lasers are bounced off reflectors left on the Moon. This provides millimeter-level accuracy.
Q: Distance between Earth and Moon to scale — how do I show it?
A: A great way is to use Earth's diameter. The Moon orbits at a distance of roughly 30 Earth diameters. This demonstrates that while diagrams often show them close, they are very far apart in real space.