Horse feed ration calculator
Most horses need 1.5–2.5% of their bodyweight in dry matter every day, with the forage-to-concentrate split driven by workload. Enter bodyweight and work level to get a daily hay and hard-feed guideline in kilograms, plus a sanity check on whether your current ration is over- or under-feeding.
The calculator itself is interactive and loads with the page. It is free, needs no signup, and nothing you enter is stored.