An interactive tool for determination of catenary sag correction and true length for tape measurements; available for metric and imperial units.
Notes on Tape Sag Correction 'Catenary' Calculator (metric)
- Select the required output, then set the other parameters to the required values.
- This tool works with metric units; for an imperial units version click the "Imperial Units" button.
For a more complete definition of Catenary and the formula, see below.
When a tape is suspended from each end, it forms a curve
called a catenary
. Because the curve is longer than the straight-line distance
between the ends of the tape, the tape always reads longer than the actual
distance. The correction is therefore a negative quantity.
If the weight of the tape is w kilograms per
meter, kg/m (or pounds per foot, lb/ft) , the unsupported length of tape is
l meters (or feet), P is the tension applied to the tape in
kilograms (or pounds), then the sag correction, Cs
, will be
Consistent units, metric or imperial must be used throughout.
'corrected' value = measured value - correction
Values displayed with a may be changed ... click on a value to display an entry form ... or use the arrows right of a value to select from a list.
This tool exhibits spreadsheet-like behaviour ... change a value and related values are re-calculated automatically.