Total Station Distance Correction Calculator

Work out total station distance correction instantly with clear inputs, formula shown and shareable results.

About Total Station Distance Correction Calculator

An electronic distance measurement is corrected in three steps: the atmospheric correction in parts per million for the prevailing temperature and pressure, the prism constant offset, and finally reduction to the horizontal by the cosine of the vertical angle. At 250 metres a 12 ppm error is only 3 mm, but on a two kilometre line it becomes 24 mm.

Formulas

Corrected slope distance

Corrected = measured x (1 + ppm / 10^6) + prism constant

Reduction

Horizontal = corrected x cos(vertical angle); height difference = corrected x sin(vertical angle)

Worked example

With the default values below, Total Station Distance Correction Calculator returns Horizontal distance of 249.3725. Change any input above and every figure here is recalculated in your browser.

Inputs used

Measured slope distanceminimum 0.001 m: 250.456 m
Vertical angleaccepts -89–89 °: 5.25 °
Atmospheric correctionaccepts -200–200 ppm: -12 ppm
Prism constantaccepts -100–100 mm: -30 mm

Results

Horizontal distance: 249.3725 m
Corrected slope distance: 250.4230 m
Atmospheric correction applied: -0.00301 m
Difference in height: 22.9141 m

Step by step

1Values used
2Corrected slope distance
3Reduction
4Horizontal distance= 249.3725 m
5Corrected slope distance= 250.4230 m
6Atmospheric correction applied= -0.00301 m
7Difference in height= 22.9141 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 5 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 Total Station Distance Correction figure worked out?

Corrected = measured x (1 + ppm / 10^6) + prism constant. An electronic distance measurement is corrected in three steps: the atmospheric correction in parts per million for the prevailing temperature and pressure, the prism constant offset, and finally reduction to the horizontal by the cosine of the vertical angle.

Why does the prism constant matter so much?

It is an offset, not a proportion, so it applies equally to every distance. Mixing a minus 30 mm prism with an instrument set for zero introduces a constant 30 mm error into every measurement.

What values do I need to enter?

This calculator takes 4 inputs: Measured slope distance, Vertical angle, Atmospheric correction, Prism constant. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.