Level / RL Calculator
A complete level book in the browser: reduced levels by the height-of-instrument or rise-and-fall method, the arithmetic checks worked out for you, closing error against the closing benchmark, and the correction distributed over the setups.
Leave a cell empty when there is no reading. A line with both a back sight and a fore sight is a change point. A negative staff reading is treated as an inverted staff, exactly as in a written level book.
Both methods, both checks. Height of instrument: HI = RL + BS, and every RL = HI − (IS or FS). Rise and fall: each reading is compared with the one before it on the same setup, giving a rise or a fall. The classic checks are printed with the result — ΣBS − ΣFS must equal the last RL minus the first, and in the rise-and-fall method it must also equal Σrise − Σfall. If any of those disagree the tool says so instead of quietly presenting the levels. Closing error is the computed RL of the last point minus its known RL, and the allowable figure is the familiar C√K millimetres with C and the route length K as you enter them — a common specification, but always check what your own project demands. The correction, when applied, is distributed in proportion to the number of setups, which is the usual practice for a simple line of levels.
Levelling, contours and volumes by BTPL
Precise levelling networks, DTM and contour generation, and cut-and-fill volumes for roads, canals, tanks and development sites.