One kilogram is 35.2739619496 ounces. The pair spans an awkward ratio — one unit is about thirty-five times the other — which is why the conversion is usually done through pounds rather than directly.
About the units
The kilogram is the SI base unit of mass, defined through the Planck constant since 2019. The avoirdupois ounce is one sixteenth of a pound, exactly 28.349523125 grams. Because a kilogram is a little over two pounds, it is a little over thirty-two ounces, and the extra three ounces on top of that are what make the figure hard to estimate by eye. The two units also sit at different places in their own systems: the kilogram is a base unit that everything else derives from, while the ounce is a subdivision two steps down from the pound, which is itself defined in kilograms.
The exact factor
The exact derivation is 1 kg ÷ 0.028349523125 kg = 35.27396194958041..., repeating. Equivalently, 2.2046226218 pounds times sixteen ounces. Useful anchors: 500 g is 17.64 oz, 100 g is 3.53 oz, and 1 oz is 28.35 g. For rough kitchen work, treating a kilogram as 35 ounces is under by less than one per cent, which is well inside the accuracy of a domestic scale.
Where you meet this conversion
Food packaging that crosses borders is the main case, since a product made to a metric net weight has to carry an imperial equivalent on American shelves — a 500 g package becomes "17.6 oz" and a 1 kg bag becomes "2 lb 3.3 oz". Postal and courier rate cards convert the same way. Recipe conversion is the other frequent use, particularly when a European recipe specifying kilograms of an ingredient has to be scaled for American measuring equipment marked in ounces.