Antipode Calculator

Someone asks where you would end up if you dug straight through the planet—and suddenly you are juggling north versus south, wondering whether to add or subtract 180 degrees of longitude, and second-guessing whether your GPS export used decimal degrees or some DMS string from a survey file. The antipode is the spot on the far side of Earth connected to your location by a line through the center. It shows up in geography homework, radio propagation curiosity, travel trivia, and GIS spot checks when you need the diametrically opposite coordinates without opening a full mapping suite.

Enter your latitude and longitude as signed decimal degrees, click Calculate, and this tool returns the antipode in the same format plus a short step block showing the sign flip and longitude shift. In my experience verifying field coordinates, having the math spelled out next to the answer catches swapped signs before they propagate into a report.

How to Use This Antipode Calculator

• Enter latitude. Use decimal degrees from −90 to 90. Positive values are north of the equator; negative values are south. Example: New York City is roughly 40.7128 (north, so positive).
• Enter longitude. Use decimal degrees from −180 to 180. Positive is east of the prime meridian; negative is west. Example: New York City is roughly −74.0060 (west, so negative).
• Click Calculate. The result panel shows the antipode as formatted coordinates with hemisphere letters (N/S, E/W). Step-by-step work appears below when you need to document the transformation.
• Validate inputs before sharing. If you see an error message, check for out-of-range values, stray commas, or DMS notation pasted without conversion—this tool expects plain decimal degrees only.

Think of the globe like a ball on a pencil through the north and south poles: the antipode is where the pencil tip would poke out on the other side. For surface routing between two arbitrary points—not the opposite side of the planet—use the Latitude Longitude Distance Calculator. When you need bearing from one coordinate to another along the surface, the Azimuth Calculator handles forward azimuth and great-circle distance together.

Antipode Calculator Formulas and Practical Applications

On a sphere, the antipode inverts latitude across the equator and shifts longitude by half a turn around the axis. The implementation here matches standard geodetic practice: flip the latitude sign, adjust longitude by 180°, then wrap longitude into the conventional −180° to 180° range.

Let input latitude be θ and input longitude be φ (decimal degrees):

θ_a = −θ

φ_a = φ + 180° when φ ≤ 0

φ_a = φ − 180° when φ > 0

Normalize φ_a so it stays between −180° and 180° by adding or subtracting multiples of 360° as needed.

Example: starting at θ = 40.7128° (north) and φ = −74.0060° (west)—roughly Manhattan—the antipode latitude is θ_a = −40.7128° (south) and longitude is φ_a = −74.0060° + 180° = 105.9940° east, placing the opposite point in the Indian Ocean southwest of Australia. That result is typical: most inhabited land antipodes fall in open water because oceans dominate the globe.

Where antipode math shows up in practice

• Education and mapping literacy. Students and GIS newcomers use antipodes to internalize how latitude and longitude relate on a sphere—not on a flat map projection.
• Radio and satellite intuition. Operators sometimes reference the far side of Earth when discussing great-circle paths, though real propagation depends on ionosphere and terrain—not just geometry.
• Data QA. When a CSV of coordinates looks mirrored across the equator or shifted 180° in longitude, comparing to a computed antipode quickly reveals sign or hemisphere mistakes.
• Travel and trivia. "Dig to China" jokes aside, checking the antipode answers whether your backyard theoretically opens into land or sea on the other side—useful for classroom demos and blog posts.

Surface distance from any point to its antipode is half a meridian circle—about 20,015 km (12,437 mi) on a mean Earth radius of 6,371 km. That is the same half-circumference the Latitude Longitude Distance Calculator would report between a point and its antipode along a great circle.

Standard Units and Conversion Tables

This calculator accepts decimal degrees (DD) only. Survey exports, aviation briefings, and older paper maps often use other formats—convert before entering values here.

Latitude and longitude format reference

• Decimal degrees (DD): Single signed number per axis. Example: 48.8566, 2.3522 for Paris (north and east, both positive). This tool uses DD end to end.
• Degrees decimal minutes (DDM): Degrees plus minutes with a decimal fraction. Example: 48° 51.396′ N, 2° 21.132′ E. Convert minutes to a decimal fraction of a degree before entry: 51.396 ÷ 60 ≈ 0.8566 added to 48 gives 48.8566°.
• Degrees minutes seconds (DMS): Three-part sexagesimal values. Example: 40° 42′ 46″ N, 74° 0′ 22″ W. Convert seconds to minutes, then minutes to degrees: 46 ÷ 3600 + 42 ÷ 60 + 40 ≈ 40.7128° north and −(0 + 0 + 74) ≈ −74.006° west when the direction is W.
• Sign conventions: N and E are positive; S and W are negative in DD. Do not append N/S/E/W in the input boxes—use the sign instead.
• Valid ranges: Latitude −90° to 90°; longitude −180° to 180°. Values at exactly ±180° longitude represent the same meridian; the calculator normalizes output longitude into that interval.

Quick decimal-degree examples

• Equator, prime meridian: 0, 0 → antipode 0, 180 (or 0, −180).
• North Pole: 90, any longitude → antipode −90 (south pole); longitude is undefined at poles but the tool still applies the longitude shift.
• 45° N, 90° W: 45, −90 → antipode −45, 90 (45° S, 90° E).

Frequently Asked Questions

What is an antipode on Earth?

The antipode is the point on the opposite side of Earth from your location, connected by a straight line through the planet's center. If you could tunnel straight down, you would emerge at the antipode.

How do you calculate antipode coordinates from latitude and longitude?

Flip the sign of latitude (north becomes south and vice versa). For longitude, add 180° if the original longitude is negative or zero, subtract 180° if positive, then normalize to the −180° to 180° range.

What coordinate format does this calculator accept?

Enter decimal degrees only: latitude from −90 to 90 and longitude from −180 to 180. Negative latitude is south, negative longitude is west. Use a minus sign, not a trailing direction letter.

Is the antipode always on land?

No. Most antipodes fall in the ocean because water covers roughly 71% of Earth's surface. Only a small fraction of locations have antipodes on dry land—often in remote regions.

How far is it from a point to its antipode?

The surface distance along a great circle is half Earth's circumference—about 20,015 km (12,437 mi) using a mean radius of 6,371 km. The straight-line distance through the core is Earth's diameter, roughly 12,742 km.