Height of instrument calculator

You obtain it by adding the backsight staff reading on a known benchmark to that benchmark’s elevation: HI equals BM plus BS. This height of instrument calculator accepts the known benchmark elevation and the backsight staff reading in any consistent length unit, returns the rounded HI with the classic formula string and ordered substitution steps, and rejects negative staff readings as invalid_input instead of producing a meaningless collimation height.

What height of instrument means in differential leveling

The standard way to establish HI at a setup is to take a backsight (BS) on a point of known elevation—typically a permanent benchmark or a turning point from a previous setup—and add that staff reading to the known elevation: HI equals BM plus BS. This endpoint returns the rounded benchmark elevation and backsight you supplied, the computed height of instrument, the precision used, a method tag differential_leveling_hi, formula as the string HI equals BM plus BS, message as a short English summary, and steps as an ordered substitution log. There is no multi-setup reduction, no balancing of sights, and no error-of-closure adjustment: the engine either adds two finite numbers inside the supported magnitude range or rejects the input with invalid_input.

Input contract, response shape, and error behaviour

Both must be finite numbers; backsight must be non-negative because a staff graduation cannot read below zero in this contract. Prefer sending numbers rather than pre-formatted strings when you control the client; when you must send strings, avoid unit labels that would fail the finite-number pattern. Send a JSON body with two required fields: benchmark_elevation for the known elevation of the point where the staff is held for the backsight (aliases BM, bm, elevation, benchmark, known_elevation, elev_bm) and backsight for the staff reading on that point (aliases BS, bs, backsight_reading, staff_reading, bs_reading). Optional precision (aliases decimals, dp) chooses how many decimal places to expose for numeric fields, defaulting to twelve and capped at fifteen so JSON goldens stay stable across runtimes. String forms of numbers are accepted when they match a strict finite decimal pattern with optional scientific notation; embedded spaces, unit suffixes such as m or ft, and non-numeric tokens fail with a clear invalid_input message naming the field. On success the response echoes the rounded inputs, publishes height_of_instrument as BM plus BS, formula and message as described above, and steps as the substitution log you can assert in tests or show next to a field-book sketch. Failed validation—missing fields, non-finite numbers, negative backsight, or values outside absolute magnitude limits—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item. Pair this endpoint with a foresight reduction when you already know HI and need a new point elevation as HI minus FS; this page answers only the single-setup height of instrument from BM and BS.

Where a height of instrument calculator earns its keep

On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split—free interactive exploration and a priced, identical API—matches the rest of the KIT tier-A catalog and lets you move from a classroom demo to an automated pipeline without changing the mathematical result. Keep this tool for the elementary HI equals BM plus BS step; if you need multi-setup reductions, closure checks, or three-wire leveling averages, reduce each setup’s HI with this endpoint first or use a model dedicated to full circuit adjustment.