Coordinate Difference Calculator
Differences, horizontal and slope distance, grid bearing and grade between two points — or two whole point lists joined by ID — with blank heights kept blank.
Inputs
ΔE, ΔN and ΔRL between two points, with horizontal and slope distance, grid bearing and grade — or two whole lists joined by ID.
Enter the values and press Calculate.
Or load an example to see a worked result.
Batch from CSV
One row per calculation, with a header row. Values use the units currently selected in the form above. Up to 10,000 rows; nothing is uploaded.
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Choose two points or two lists, and the coordinate unit (metres or feet).
- Enter easting, northing and (optionally) RL for each point — a blank RL is unknown, not zero.
- Optionally declare each point's reference; unlike references are blocked.
- Press Calculate and read the horizontal distance, grid bearing, ΔE/ΔN/ΔRL, slope distance and grade.
How it works
ΔE = E₂ − E₁, ΔN = N₂ − N₁, ΔRL = RL₂ − RL₁ (only when both RLs exist). Horizontal D = √(ΔE² + ΔN²); slope S = √(D² + ΔRL²).
Grid bearing = atan2(ΔE, ΔN), clockwise from grid north. When the points coincide in plan there is no bearing — it is shown as undefined, not 0°. Grade = 100 × ΔRL ÷ D is not finite for a vertical-only pair.
List mode joins two CSV lists by exact ID (duplicate or case-ambiguous IDs stop the join) or by row order — never by nearest point — and runs every pair through the same engine. For the same mark measured twice it adds mean signed deltas, component RMSE and the largest residuals, checked against your own tolerance.
Worked example
P1 (100, 200, 10) to P2 (103, 204, 22). ΔE = 3, ΔN = 4, ΔRL = 12. D = √(3² + 4²) = 5 m; S = √(5² + 12²) = 13 m; bearing = atan2(3, 4) = 36.869898°; grade = 100 × 12 ÷ 5 = 240 %. Swapping the points gives −3, −4, −12 and a bearing of 216.869898°, with the same distances.
Frequently asked questions
Why is the bearing 'undefined' instead of 0°?
0° is a real bearing (due north). Two points at the same easting and northing have no direction at all, so the tool says so.
Is this a ground distance?
It is a grid distance on the coordinates as entered. Converting to ground distance needs a combined scale factor, and comparing points on different datums needs a transformation first.
Can I compare a whole survey against a previous one?
Yes — paste both lists, join them by point ID, choose 'the same mark twice' and enter your tolerance. The table and CSV show every pair, including unmatched IDs.
Related tools
- Coordinate Offset Calculator
- Coordinates to Bearing & Distance Calculator
- Combined Scale Factor Helper
- Prism Constant Check Calculator
- Datum Shift Magnitude Calculator
- Slope & Horizontal Distance Calculator
Explore more in Surveying, Coordinates, GIS & CAD.
Cite this tool
Zerdly. (2026). Coordinate Difference Calculator. Retrieved from https://www.zerdly.com/tools/coordinate-difference-calculator/
Tip: Enter any known values to calculate the remaining results.
Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.