Fluid ounce per second (fl oz/s)

The fluid ounce per second is a unit of volumetric flow rate equal to one imperial fluid ounce passing a point every second. Its symbol is fl oz/s. The imperial fluid ounce is 28.413 millilitres, defined as one twentieth of an imperial pint, so this unit describes the flow of a steady pour rather than a plumbing system.

Its natural home is the bar and the kitchen. A pint glass filled in twelve seconds is being poured at about 1.7 fluid ounces per second, and a bartender free-pouring spirits counts seconds against a known rate to measure a shot without a jigger. Automatic dispensing guns on a bar are calibrated in exactly these terms so that a portion is repeatable across a busy evening.

Beverage plants use it for filling heads. A bottling line filling half-litre bottles at 200 bottles a minute must deliver about 59 fluid ounces per second in total, divided among however many heads the filler carries. Each head's individual rate determines the fill time, and the fill time determines how fast the carousel can turn.

The unit persists in British and Commonwealth food and drink specifications, where recipes, dispense rates and portion controls have been written in fluid ounces for generations. A soft-drink dispenser is set so that the syrup and the carbonated water arrive in a fixed ratio, and both rates are naturally quoted in fluid ounces per second.

A warning belongs here: the American fluid ounce is 29.574 millilitres, about four per cent larger than the imperial one, and the American pint holds sixteen of them against the imperial twenty. A flow rate quoted in fluid ounces per second therefore differs by four per cent between the two systems, and by twenty per cent when the same number of ounces is called a pint.

For a sense of scale, 35 fluid ounces per second is about a litre per second, and one fluid ounce per second fills a pint in twenty seconds and a gallon in a little under three minutes. It is the rate of a fast tap or a generous jug.

One fluid ounce per second equals about 28.41 millilitres per second, about 0.02841 litres per second, or about 1.734 cubic inches per second.

Fluid ounce per second conversion table