The short version
One ounce is 28.3495 grams. That single number turns any ounce value into grams. Punch in the ounces, the grams show up right away, and the dropdown handles the reverse trip or a hop to pounds and kilograms.
Why bother? Because half the world weighs food and parcels in grams, and a recipe or a shipping label written in ounces doesn’t help if your scale only shows metric.
Under the hood
grams = ounces x 28.3495
The factor isn’t a guess. An ounce is officially 28.349523125 grams, derived from the pound’s exact definition. We keep enough precision that a 12 oz value resolves to 340.19 g, not a hand-wavy 340. That precision earns its keep when a recipe’s chemistry depends on getting the flour-to-liquid ratio right, or when a package sits a gram away from the next postage tier.
Numbers you’ll reach for
| Ounces | Grams |
|---|---|
| 1 oz | 28.35 g |
| 2 oz | 56.70 g |
| 4 oz | 113.40 g |
| 8 oz | 226.80 g |
| 12 oz | 340.19 g |
| 16 oz | 453.59 g |
| 1 oz (troy) | 31.10 g |
That 16 oz row equals a pound, which lands at about 453.6 g, just shy of half a kilogram. And yes, 8 oz (a cup of water by weight, roughly) is 226.8 g, the reason a “stick” of US butter is so often labeled 113 g.
When you’d use this
Following recipes is the headline use. American cookbooks and food blogs love ounces for both dry and wet ingredients, but metric kitchen scales read grams. Converting 6 oz of chocolate to 170 g lets you scoop the right amount instead of eyeballing it.
Postage and parcels are right behind. US postal rates step up by the ounce, yet plenty of scales (and most of the world’s shipping systems) work in grams. If a rate chart says 13 oz is the limit for a class of mail, that’s 368.6 g, the line your scale needs to stay under.
There’s a long tail too: portioning meat and cheese at the deli counter, dosing pet food by the ounce when the bag is metric, weighing coffee for a brew ratio. Anywhere an ounce figure meets a gram scale, this bridges them.
Don’t trip on these
Fluid ounces are not weight ounces. A fluid ounce measures volume (about 29.57 ml), while the ounce here measures mass. “8 fl oz of milk” and “8 oz of cheese” are different kinds of measurement, and converting fluid ounces to grams only works if you know the liquid’s density.
The troy ounce is the other gotcha. Gold and silver are priced per troy ounce (31.1035 g), heavier than the standard 28.3495 g ounce this tool uses. Use the right one or your bullion math will be off by about 10 percent.
Everything is computed locally in the browser. Your entries aren’t uploaded, and the converter keeps running offline once loaded.
FAQ
How many grams in an ounce?
28.3495 g. So 4 oz is 113.4 g and 8 oz is 226.8 g.
Quick way to estimate?
Multiply ounces by 28. A 10 oz item is roughly 280 g, and the exact figure is 283.5.
Is a fluid ounce the same as this ounce?
No. A fluid ounce is volume (about 29.57 ml). This converts weight ounces to grams, which is a different measurement.
What about gold and silver?
Those use the troy ounce (31.1035 g), which is heavier. This tool uses the standard 28.3495 g ounce, so it isn’t the right one for precious metals.
Does it send my numbers anywhere?
Nope. All math runs in your browser, so nothing reaches a server.