Trilateration Position Calc
3-Point Position Solve
$1.99 · Designed for iPad. Not verified for macOS.
Three known points, three measured distances - solve for the unknown XY. 2D plot, two candidates, linearized determinant cross-check. $1.99 one-time, no login.
Built for surveyors, accident reconstructionists, and field engineers who need a quick three-point position solve - not a CAD package, not a desktop tool.
WHAT IT DOES
Solves for a 2D position given three reference points and three measured distances. Uses circle-intersection algebra (two-candidate nonlinear solution) plus a linearized 2x2 reduced system as cross-check. Plots all three reference circles and both candidate solutions on a 2D canvas with tolerance rings and per-anchor distance-error verification.
INPUTS
- Three reference points: (x1, y1, r1), (x2, y2, r2), (x3, y3, r3)
x, y in any consistent unit (feet, meters, mm - your choice)
r is the measured distance from each reference point to the unknown
- Tolerance for solution validity (default 0.001)
RETURNS
- Solution 1 and Solution 2 (x, y) from the nonlinear solve
- Linearized solution from the 2x2 reduced system
- Linearized determinant value (flags degenerate / parallel cases)
- Per-solution distance verification: actual vs. expected, error
- Validity flag for each candidate based on tolerance
WHY THIS APP, NOT THE FREE ONES
- Math is shown - both solve methods rendered, not just the final coordinates.
- Visual cross-check - 2D plot of anchor circles, candidates, and tolerance rings.
- Works offline - staking jobs, accident scenes, GPS-shadow zones.
- No login. No ads. No telemetry. No subscription.
PRICING
$1.99. Pay once, own it. Lifetime access on iPhone, iPad, and Mac via Family Sharing.
NOT A SUBSTITUTE FOR
PLS-stamped boundary survey work. Geodetic-grade total stations or RTK GPS for legal coordinates. This is a quick verification tool - not legal-survey-grade equipment.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Added a More Pro Tools section to discover related field calculators.
The developer, Shanghai Sheyuan Network Technology Co., Ltd., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Shanghai Sheyuan Network Technology Co., Ltd.
- Size
- 969.7 KB
- Category
- Utilities
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Sheyuan Inc.
