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A total station is an electronic surveying instrument that measures both angles and distances from a single point, then calculates and stores the three-dimensional coordinates of targets. It combines a theodolite (for angle measurement), an electronic distance measurer (EDM), and a data collector into one integrated unit mounted on a tripod. The operator aims the instrument at a reflective prism or bare surface, presses a button, and within seconds has both the horizontal and vertical angles plus the slant distance to that point.

The core measurement technology relies on an infrared or red laser that bounces off a reflector (usually a prism mounted on a pole) or directly off a surface, with the instrument measuring the time delay to calculate distance. Angular measurements come from rotatable glass circles read by electronic sensors accurate to seconds of arc. Most modern total stations store hundreds or thousands of measurements in internal memory and output data via USB or wireless connection to surveying software on a computer or tablet.

Common variants and work envelope

A reflectorless total station can measure distances up to 300 metres or more directly to unprepared surfaces like rock faces or buildings, eliminating the need for a prism. Reflectorless models sacrifice some accuracy and range but gain speed and flexibility on construction sites. Robotic or motorized total stations can be aimed and measured remotely from a handheld controller, useful when one person needs to work alone. Standard prism-based instruments typically work to ranges of 200 to 5000 metres depending on prism size and atmospheric conditions.

On construction sites, a total station sets out building positions, foundation corners, and level grades by reverse calculation: the operator enters known coordinates, and the instrument tells workers where to place markers. Surveyors use them to establish property boundaries and create topographic maps. The accuracy of modern instruments ranges from roughly 2 to 5 millimetres over typical working distances, with angular precision to 1 or 2 seconds of arc on general-purpose models.

Common errors include poor tripod setup (tilt or unstable ground introduces systematic angle and distance errors), atmospheric refraction (water vapour and temperature gradients bend the laser beam slightly), and prism misalignment. Dust or moisture on the lens degrades distance measurement. The term total station emerged in the 1970s when electronic distance measurement and digital angle reading were first combined in a single compact instrument, replacing survey crews who used separate theodolites and chains.