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Chain Survey Offset Calculator

Work out chain survey offset instantly with clear inputs, formula shown and shareable results.

About Chain Survey Offset Calculator

An oblique offset has to be resolved into a component perpendicular to the chain line and a component along it, which shifts the effective chainage. Once resolved, the point is plotted by moving along the line bearing and then at right angles to it, giving coordinates relative to the start of the line.

Formulas

Offset resolution

Perpendicular = offset x sin(angle to line); along-line = offset x cos(angle to line)

Coordinates

Move effective chainage along the line bearing, then the perpendicular component at bearing plus 90 degrees

Worked example

With the default values below, Chain Survey Offset Calculator returns Perpendicular component of the offset of 8.0000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Chainage along the survey lineminimum 0 m
45 m
Offset lengthminimum 0 m
8 m
Angle of the offset to the chain lineaccepts 1–179 °
90 °
Bearing of the chain lineaccepts 0–360 °
45 °

Results

Perpendicular component of the offset
8.0000 m
Along-line component of the offset
0.0000 m
Easting relative to the line start
37.4767 m
Northing relative to the line start
26.1630 m

Step by step

  1. 1Values used
  2. 2Offset resolution
  3. 3Coordinates
  4. 4Perpendicular component of the offset= 8.0000 m
  5. 5Along-line component of the offset= 0.0000 m
  6. 6Easting relative to the line start= 37.4767 m
  7. 7Northing relative to the line start= 26.1630 m

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Chain Survey Offset figure worked out?

Perpendicular = offset x sin(angle to line); along-line = offset x cos(angle to line). An oblique offset has to be resolved into a component perpendicular to the chain line and a component along it, which shifts the effective chainage.

Why are oblique offsets used at all?

To locate a point that cannot be reached at right angles, or to fix a boundary corner by two oblique ties which also provides a check that a single perpendicular offset does not.

What values do I need to enter?

This calculator takes 4 inputs: Chainage along the survey line, Offset length, Angle of the offset to the chain line, Bearing of the chain line. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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Chain Survey Offset Calculator | Calcrivo