# Distance Calculator

> Calculate distance in 2D, 3D, or between two latitude/longitude coordinates on Earth.

Page: https://askcalculators.com/calculator/distance-calculator/
Definition: https://askcalculators.com/calculator/distance-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/distance-calculator/schema.json
Version: 2.0.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/distance-calculator/?mode=2d&x1=0&y1=0&x2=3&y2=4

## Inputs
- mode: Distance model; type=select; required; default=2d; values=2d|3d|geographic
- x1: x₁; type=number; required; default=0; showWhen=mode:2d
- y1: y₁; type=number; required; default=0; showWhen=mode:2d
- x2: x₂; type=number; required; default=3; showWhen=mode:2d
- y2: y₂; type=number; required; default=4; showWhen=mode:2d
- x1Three: x₁; type=number; required; default=0; showWhen=mode:3d
- y1Three: y₁; type=number; required; default=0; showWhen=mode:3d
- z1Three: z₁; type=number; required; default=0; showWhen=mode:3d
- x2Three: x₂; type=number; required; default=3; showWhen=mode:3d
- y2Three: y₂; type=number; required; default=4; showWhen=mode:3d
- z2Three: z₂; type=number; required; default=12; showWhen=mode:3d
- latitude1: Latitude 1; type=number; required; default=40.7128; min=-90; max=90; showWhen=mode:geographic
- longitude1: Longitude 1; type=number; required; default=-74.006; min=-180; max=180; showWhen=mode:geographic
- latitude2: Latitude 2; type=number; required; default=51.5074; min=-90; max=90; showWhen=mode:geographic
- longitude2: Longitude 2; type=number; required; default=-0.1278; min=-180; max=180; showWhen=mode:geographic

## Outputs
- distance: Distance; format=number; primary
- distanceKilometers: Distance; format=number
- distanceMiles: Distance; format=number
- deltaX: Δx; format=number
- deltaY: Δy; format=number
- deltaZ: Δz; format=number
- initialBearing: Initial bearing; format=number
- midpoint: Midpoint; format=text

## Formula
Cartesian: d=√[Σ(qᵢ−pᵢ)²]; geographic: d=2R·asin(√[sin²(Δφ/2)+cosφ₁cosφ₂sin²(Δλ/2)]).

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.