A 20× optical dumpy level for height difference measurement, building layout and road levelling surveys — Multi Trade Combines stocks entry contractor sets at Guwahati, price on request.
A dumpy level (or auto level / automatic level) is an optical surveying instrument that establishes a precise horizontal line of sight, used to measure height differences between points on the ground. The instrument is set up on a tripod, levelled using the circular bubble, and then sights through the telescope to a graduated staff rod held vertically at each point to be measured. The difference in staff readings between two points gives the height difference — the fundamental measurement in all levelling surveys.
In construction, a dumpy level is used for setting out floor levels, checking the level of concrete pours, setting formwork height, checking road sub-grade levels, setting drain invert levels, and transferring benchmark heights around a site. In survey fieldwork it is used for differential levelling between survey benchmarks, longitudinal section surveys for road and canal design, and cross-section surveys.
Multi Trade Combines stocks 20× entry contractor sets at our AT Road, Guwahati counter — including the level instrument, tripod and 4-metre telescoping staff — ready for immediate site use by contractors across Northeast India.
| Category | Surveying Instruments |
|---|---|
| Key specs | 20× — entry contractor sets |
| Magnification | 20× — clear staff reading to 50 m typical working range |
| Compensator | Automatic compensator — self-levelling within ±15 arcminutes |
| Accuracy | Standard levelling accuracy ±2–3 mm per km |
| Kit contents | Level instrument + aluminium tripod + 4 m telescoping staff (entry set) |
| Availability | In stock — price on request |
Complete survey and setting-out equipment for site use:
Both terms are used interchangeably in India for modern optical levels. Technically, the original 'dumpy level' was a fixed-telescope instrument that required manual levelling of the telescope. Modern 'auto levels' or 'automatic levels' use a compensator pendulum that automatically corrects for small levelling errors once the bubble is roughly centred — they self-compensate within ±15 arcminutes. All modern optical levels sold in India (including the 20× entry sets we stock) are auto-compensating levels. The term 'dumpy level' persists in common NE India field usage to mean any optical staff-reading level instrument.
A 20× magnification is the entry-level for general construction levelling — it reads a staff clearly at typical building-layout distances of 30–50 metres. For longer sight distances (road and railway levelling, pipeline surveys over 100 m sight), 24× or 28× gives a sharper staff reading at distance. For precise geodetic levelling on large infrastructure projects, 32× or higher with parallel plate micrometer is used. For a typical building contractor or entry-level surveyor in Assam doing floor levels, DPC heights, road sub-grade and drain invert levels, a 20× auto level is practical and economical.