How is transformer oil capacity calculated for a unit?

Oil volume is determined from tank geometry, radiator or cooler volume, conservator volume where used, and internal free space around active parts. Manufacturers provide nameplate or drawing values for total oil volume and sometimes separate “oil in main tank” vs “oil in radiators.” For retrofits or field estimation, technicians use dimensional calculations and calibration tables, accounting for thermal expansion and required headspace. Accurate capacity matters for logistics, spill planning, and correct filling level settings.