Antipode Calculator
Find the point on the exact opposite side of the Earth from any coordinate, in decimal degrees or degrees, minutes and seconds.
🌍 What is an Antipode Calculator?
An antipode is the point on the Earth's surface exactly opposite another point, the place you would arrive at if you could drill straight through the planet's centre and keep going. Antipodal pairs are as far apart as two points on Earth can be: about 20015 km along the surface and roughly 12730 km straight through the middle. This calculator takes any latitude and longitude, in decimal degrees or in degrees, minutes and seconds, and returns the antipodal coordinate together with the through-Earth distance, the shortest surface distance and the nautical time zone on the far side.
The idea shows up in more places than the schoolyard question about digging to the other side of the world. Seismologists watch the antipode of every major earthquake, because seismic energy that spreads outward around the globe reconverges there and produces a measurable secondary pulse. Radio engineers use antipodal geometry to set the worst-case path length for long-distance propagation studies. Geodesists use antipodal and near-antipodal coordinate pairs as stress tests, since the classic inverse geodesic algorithms lose convergence precisely in that configuration. Travel writers and quiz setters use it for the fun fact that Wellington in New Zealand sits almost exactly opposite the coast of Spain.
The arithmetic itself is simple, which is exactly why mistakes are common. The latitude flips sign, so 51.5074 north becomes 51.5074 south, and the longitude moves by 180 degrees and then has to be wrapped back into the standard range. People frequently forget the hemisphere flip and conclude that the United States is opposite China, when in fact both are in the northern hemisphere and the true antipode of most of the continental United States is empty water in the southern Indian Ocean. Another regular slip is treating the through-Earth distance as a fixed 12742 km. That figure is the mean diameter, but the Earth is an oblate spheroid, so the real chord runs from 12756.27 km between equatorial antipodes down to 12713.50 km between the poles.
This calculator handles all of that. It normalises the longitude correctly across the antimeridian, keeps the antipode of longitude 0 at a clean 180 degrees east, reports the answer in both decimal and sexagesimal notation, and computes the chord from the WGS84 geocentric radius at your actual latitude rather than from a single averaged number. The schematic graticule then shows both points at once, so the mirror-and-shift relationship is visible rather than merely asserted.
📐 Formula
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 — London and the South Pacific
London at 51.5074°N, 0.1278°W
Example 2 — New York and the Indian Ocean
New York City at 40.7128°N, 74.0060°W
Example 3 — Null Island and the Antimeridian
The origin of the coordinate system, 0°N, 0°E in the Gulf of Guinea
Example 4 — Wellington in Degrees, Minutes and Seconds
Wellington, New Zealand at 41°17'11.8" S, 174°46'32.2" E
❓ Frequently Asked Questions
🔗 Related Calculators
What is an antipode?
An antipode is the point on the Earth's surface diametrically opposite a given point, the place you would reach by drilling straight through the centre of the planet. Every point has exactly one antipode, and the pair are separated by half the circumference along the surface, roughly 20015 km.
How do you calculate the antipode of a coordinate?
Flip the sign of the latitude and shift the longitude by 180 degrees, then wrap the result back into the range from -180 to 180. So latitude 51.5074 N, longitude 0.1278 W becomes latitude 51.5074 S, longitude 179.8722 E. No trigonometry is needed, it is a pure reflection through the centre of the Earth.
What is the antipode of London?
London at 51.5074 N, 0.1278 W has its antipode at 51.5074 S, 179.8722 E, in the South Pacific Ocean roughly 700 km southeast of New Zealand's Chatham Islands. Like most European antipodes it falls in open water.
Is China really on the opposite side of the world from the United States?
No. The antipode of the continental United States is the southern Indian Ocean, west of Australia. China's antipodes lie in Argentina and Chile. The dig-to-China idea survives because both countries are far apart in longitude, but they are both in the northern hemisphere, and an antipode has to flip the hemisphere too.
How far is it straight through the Earth to my antipode?
Twice the geocentric radius at your latitude. That is 12756.27 km between two equatorial points, 12713.50 km between the poles, and around 12730 km for mid-latitude locations. This calculator uses the WGS84 ellipsoid, so the number changes slightly as you move north or south.
How far is it along the surface to my antipode?
Half a great circle, about 20015 km on a mean-radius sphere, and that figure is the same wherever you start. What changes is the route: between antipodal points every direction is equally short, so an infinite number of shortest paths exist.
Why do so few places have land at their antipode?
Because land and ocean are distributed asymmetrically. Around 71 percent of the surface is water, and the continents are concentrated in the northern hemisphere while the southern hemisphere is mostly ocean. The result is that only about 4 percent of land has land opposite it, mainly Spain to New Zealand, Chile to China and parts of Southeast Asia to South America.
What time is it at my antipode?
Solar time differs by twelve hours, since the longitudes differ by exactly 180 degrees. Clock time can differ by more or less because political time zones do not follow meridians, and because the antipode may sit on the other side of the International Date Line, putting it on a different calendar day.
Does every point have exactly one antipode?
Yes. The mapping is a one-to-one involution: apply it twice and you return to where you started. The North Pole and South Pole are antipodes of each other, and the poles are the only points whose antipode does not depend on longitude at all.
How do I convert degrees, minutes and seconds for this calculator?
Decimal degrees equals degrees plus minutes divided by 60 plus seconds divided by 3600, with the sign set by the hemisphere. For example 41 degrees 17 minutes 11.8 seconds south is -(41 + 17/60 + 11.8/3600) = -41.2866. This calculator has a DMS mode so you can enter the parts directly.
What is the antipode of the North Pole?
The South Pole. Latitude 90 N flips to 90 S, and longitude becomes irrelevant because every meridian converges at the poles. It is the one antipodal pair where the longitude shift makes no difference to the answer.
Are antipodes used for anything practical?
Yes. Seismologists use them because seismic waves from a large earthquake refocus near the antipode, producing measurable ground motion there. Radio and satellite planners use them to define the worst-case propagation distance, and geodesists use antipodal pairs to test the numerical stability of inverse geodesic solvers, which famously struggle near-antipodal cases.