The antipode calculator above finds the point on the far side of the planet from any coordinate you give it — the place you would arrive at if you could drill straight through the centre of the Earth and keep going. The arithmetic is short: flip the sign of the latitude, and shift the longitude by 180 degrees, wrapping back into range. What takes longer is saying precisely what that answer means, which is the part most antipode pages skip.
Arb Digital publishes this page alongside its other geodesy tools because the antipode is a genuinely unusual case. Almost every calculation on a coordinate pair — distance, bearing, area — gives a different answer on a sphere than on the WGS 84 ellipsoid that GPS actually uses. The antipode does not. It is identical under both models, for a reason worth understanding, and the difference reappears immediately as soon as you ask how far away it is.
What This Antipode Calculator Does
It returns the antipodal coordinate in decimal degrees and in degrees, minutes and seconds, together with two distances. The surface distance is how far you would have to travel across the ground to get there. The chord is the straight-line distance through the planet, which is the diameter of the Earth measured through your particular latitude — and because the Earth is flattened at the poles, that diameter is not the same everywhere.
Longitude is normalised so the result always lands in the conventional range from −180 to 180 degrees. A point at 105° E has its antipode at 75° W, not at 285° E, even though the two describe the same meridian.
If your coordinates arrive in some other format, convert them before entering them here: our coordinates converter moves between decimal degrees, degrees-minutes-seconds and UTM grid references. If you want the distance and bearing between two arbitrary points rather than an antipodal pair, that is our great circle distance calculator, and for direction alone the azimuth calculator.
How to Use It
- Enter the latitude in decimal degrees, positive for north and negative for south, between −90 and 90.
- Enter the longitude in decimal degrees, positive for east and negative for west, between −180 and 180.
- Pick a distance unit for the surface distance and the chord.
- Read the antipode in both decimal and DMS form, and check the summary line for the exact model assumptions behind each distance.
- Paste the antipodal coordinate into a mapping service if you want to see what is there. The answer is very often open ocean.
The Formula and the Model Behind It
The antipode of a point at latitude φ and longitude λ is:
Antipodal latitude = −φ
Antipodal longitude = λ + 180, wrapped into the range −180 to 180
Here is the part that surprises people. On a sphere this is obviously exact. On the WGS 84 ellipsoid it is also exact, and not as an approximation. An ellipsoid of revolution is symmetric about its own centre: reflect every point through the centre and the surface maps onto itself. The point diametrically opposite yours therefore lies on the ellipsoid, and by that symmetry its geodetic latitude is exactly the negative of yours and its longitude exactly 180 degrees away. Unlike distance and bearing, the antipode carries no spherical-versus-ellipsoidal error at all.
The chord through the planet does depend on the model, because it is twice the geocentric radius at your latitude, and on an ellipsoid that radius varies. Using the WGS 84 semi-axes of 6,378.137 km equatorial and 6,356.752 km polar, the chord runs from 12,756.27 km through the equator down to 12,713.50 km through the poles — a difference of nearly 43 km depending on where you stand. This tool computes the geocentric radius exactly for your latitude rather than assuming a mean sphere.
How Far Away Is It, Really?
This is where the model choice comes back, and where a single confident number would be dishonest. On a sphere of mean radius 6,371.0088 km, half the circumference is 20,015.1 km, and that is the figure this calculator reports as the surface distance. It is the standard great-circle answer and it is the one to quote if you need one number.
On the WGS 84 ellipsoid there is no single answer, because antipodal points are the one case where the shortest path is not unique. Travel due north over the pole and back down and you cover half the meridian, which is 20,003.9 km. Travel along the equator, if you happen to be on it, and you cover half the equatorial circumference, 20,037.5 km. Between those extremes lies a family of paths of intermediate length, all of them geodesics. The spread is about 34 km, or roughly 0.17 per cent.
That non-uniqueness has a practical consequence beyond trivia. Vincenty’s inverse formula, the standard iterative method for ellipsoidal distance and bearing, is known to converge slowly or fail outright for nearly antipodal pairs, precisely because there is no well-defined single solution to converge on. NOAA’s National Geodetic Survey distributes its INVERSE and FORWARD geodetic software for exactly this class of computation, and NOAA’s introduction to what geodesy is explains why the shape of the Earth makes these distinctions matter.
Why Almost Every Antipode Is Underwater
Land covers under a third of the Earth’s surface, so if land were scattered at random you would expect roughly a tenth of land points to have land antipodes. The real figure is far lower, because the continents are not randomly placed: they are heavily concentrated in the northern hemisphere, and the southern hemisphere is dominated by ocean. A northern land point is very likely to sit opposite southern water.
The exceptions are memorable for that reason. Parts of eastern China sit opposite parts of Argentina and Chile. Parts of Spain and Portugal sit opposite New Zealand. Indonesia and the Amazon basin face each other. Almost everywhere else — all of North America, all of Europe north of Iberia, all of Africa, all of India, all of Australia — has an antipode in open water.
This calculator does not attempt to say whether your antipode is on land, because doing so honestly would need a coastline dataset, and any answer without one would be a guess. Take the coordinates it gives you and put them into a map.
Antipodes, Antipodal Islands and Confused Terminology
The word carries more than one meaning and they get tangled. Geometrically, an antipode is the diametrically opposite point of any sphere, and the term is used the same way in mathematics for the opposite point of any n-sphere. Colloquially, in British English, “the Antipodes” means Australia and New Zealand, which is a fossil of a specifically European viewpoint: those countries are roughly antipodal to Britain and Ireland, and not to anywhere else.
The Antipodes Islands, a subantarctic New Zealand group, are named on the same logic — they are close to antipodal to London, though not exactly. It is worth being precise about which sense you mean in any technical context, because the geometric definition applies to every point on Earth while the colloquial one applies to a single pair of regions.
Where Antipodes Actually Get Used
Seismology uses them constantly. Energy from a large earthquake travels outward in all directions and reconverges at the antipode, which can produce measurable focusing effects, and the shadow zones where certain seismic waves fail to arrive are defined by angular distance from the source. Antipodal geometry also matters in the debate over whether some very large impact structures have antipodal surface features caused by that same focusing.
Radio and satellite work uses them as a worst case: the antipode is the maximum possible great-circle separation between two points on Earth, so it bounds path length, propagation delay and the number of relay hops required. Any question of the form “what is the furthest apart two points can be?” is an antipodal question. For the general two-point case our great circle distance calculator covers it, and for coordinates in three dimensions rather than on a surface there is the 3D distance calculator.
Arb Digital builds free calculators that name their assumptions, cite their sources and still load in under a second. Browse the library, or tell us what your audience is searching for.
Browse Free Tools Talk To Arb DigitalCommon Mistakes to Avoid
- Adding 180 to the longitude without wrapping. A result of 285 degrees east is outside the conventional range and most mapping tools will reject or misplace it.
- Flipping the longitude sign instead of the latitude. It is the latitude that changes hemisphere. Getting this backwards produces a point on the wrong side of the equator.
- Quoting one figure for the distance to an antipode. On an ellipsoid the shortest path is not unique, and the spread between the shortest and longest is around 34 km.
- Assuming the chord is the same everywhere. The Earth’s diameter through the poles is about 43 km less than through the equator.
- Mixing degrees-minutes-seconds into a decimal field. Convert first; 40°42′46″ is 40.7128, not 40.4246.
Related Free Tools From Arb Digital
Convert coordinate formats with the coordinates converter, measure between two arbitrary points with the great circle distance calculator, find a direction with the azimuth calculator, work in three dimensions with the 3D distance calculator or the 3D coordinate converter, and switch to polar form with the polar coordinates converter. The full free online tools hub has the rest.
Frequently Asked Questions
Negate the latitude and add or subtract 180 degrees from the longitude, wrapping the result back into the range from minus 180 to 180. A point at 40.7128 north, 74.0060 west has its antipode at 40.7128 south, 105.9940 east.
No, and this is unusual. Both an ellipsoid of revolution and a sphere are symmetric about their centre, so the diametrically opposite point lies on the surface in both models with exactly the negated latitude and the shifted longitude. Distance and bearing do differ between the models; the antipode itself does not.
On a sphere of mean radius 6,371.0088 kilometres it is half the circumference, 20,015.1 kilometres. On the ellipsoid there is no single answer, because antipodal points have many shortest paths ranging from about 20,003.9 kilometres over the poles to 20,037.5 kilometres round the equator.
Because the Earth is flattened at the poles. The chord is twice the geocentric radius at your latitude, which runs from 6,378.137 kilometres at the equator down to 6,356.752 kilometres at the poles on WGS 84.
Probably not. Land covers less than a third of the surface and is concentrated in the northern hemisphere, so most land points face open ocean. This calculator does not judge land or sea, because doing that properly needs a coastline dataset; paste the coordinates into a map instead.
The main pairings are parts of eastern China with Argentina and Chile, parts of Spain and Portugal with New Zealand, and parts of Indonesia with the Amazon basin. North America, Europe north of Iberia, Africa, India and Australia have almost none.
Because the shortest path stops being unique. Vincenty’s inverse formula, the usual method for ellipsoidal distance and bearing, is documented as converging slowly or failing for nearly antipodal pairs for that reason.
This tool performs a coordinate transformation using published reference-ellipsoid parameters. It is for education and general reference, and it should not be used for navigation, surveying or any safety-critical positioning, where an appropriate geodetic package and a qualified surveyor are required.
