Water Hardness API
Water-hardness maths as an API, computed locally and deterministically. The convert endpoint converts a hardness value between all the common units — parts per million / milligrams per litre as calcium carbonate, grains per US gallon, German degrees (°dH), French degrees (°f), English or Clark degrees, and millimoles per litre — passing everything through ppm (1 gpg = 17.118 ppm, 1 °dH = 17.848, 1 °f = 10, 1 °Clark = 14.254), and classifies the result. The classify endpoint labels a value as soft, moderately hard, hard or very hard on the USGS/WHO scale. The softener endpoint sizes a water softener: from the hardness and the household water use it works out the grains of hardness removed per day and the grain capacity needed between regenerations. Everything is computed locally and deterministically, so it is instant and private. Ideal for water-treatment and plumbing tools, aquarium and pool apps, appliance and softener sizing, and home and lab software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is water-hardness conversion; for general unit conversion use a unit-conversion API and for swimming-pool dosing use a pool API.
api.oanor.com/hardness-api
