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Carbonating with the "Ross Method" and a set of precise electronic brewing scales

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Indooroopilly, Qld
I've been carbonating with the "Ross Method" (ramp up pressure, shake keg for a while, you can find it explained in a ton of places on this forum) for inexact results for years now, and I hadn't thought of using a set of scales to add precision before today, and I can't find any information about others doing it so I thought I'd share.

I have a set of rather precise (1g) scales that are good up to 40kg that I use for all my grain measurements. Carbon Dioxide has a density of approximately 2g/L (1.96 precisely). If you want to carbonate beer to 2 volumes, then you want to have 2 x 2 = 4g/L of CO2 in your beer. For a 19L keg, this is 76g.

You can probably see where I'm going with this.
1. Tare scales with full keg
2. Shake keg for a minute or so
3. Weigh keg to see how much CO2 you just added
4. Repeat steps 1 - 3 until you hit 76g (or whatever desired weight is based on how many vols you want)
5 (Optional) give beer a couple of hours to settle before drinking (yeah, right...)

I realise not everyone has a set of scales to do this, but for those who do, enjoy. Feel free to critique my calculation/method.


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Mandurah WA
Thx Coxy, so inversely I can weigh my keg prior to C02, carbonate (non Ross) weigh it again after a three weeks and that will tell me the exact vol of C02 that I like?


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I've tried this method, except I put the CO2 bottle on the scales, tared it and then measured the weight loss as the CO2 transferred into the Keg. It lets you keep track of the CO2 in 'real time' as you're rocking and rolling the keg, but you need to have something to support the CO2 tube near the bottle so you don't affect the weight on the scales as you move the keg end of the tube. It worked well and the beer was ready to drink about 30 minutes later after the foam in the keg died down a bit.

The only thing I would add is that if you're kegging straight from a fermenter then force carbing, there will already be some CO2 in the beer from the fermentation. Around 0.7 to 1.0 volumes is usually assumed in the bulk priming calculators. If you want to get 2.5 volumes total then you only need to add around 1.7 volumes by force carbing.

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