This is relevant for people who have money in reserve for a rainy day, or for some planned expense in the future. I just want to shed light on it with some actual numbers.
You can also use investment, or diverse funds, but this is for those who have money, and almost everybody have some amount, small or large.
Starting out with USD users. The consumer inflation is 2%, but this is the Fed's preferred rate, and it is important for investors and analysts. The actual rate of price inflation for you and your personal mix of consumer goods and services can be quite different. You can try to estimate it, if you remember, or have accounts of your spending last year. For most people it will be higher, my guess at least 5%, and for some, 10%. All of this depends on your life situation and spending preferences.
We are interested in the future price inflation of course. In smaller countries you can see the USD rate of the local currency change first, then price inflation will come later. Here is an example from South Africa, one of the least backwards countries in Africa: https://www.tradingview.com/symbols/USDZAR. You see that 14.24 a year ago, now 15.62. (Date 2020-03-02) This is a devaluation compared to the USD of 9.7%. Since most smaller countries import a large part of their consumables, this is a driver for local price inflation. It depends on many things, so you can not just add them together.
The reality is that in many countries, you can expect or risk a consumer price inflation of 5 - 20%, and that is not hyperinflation, that is rather a normality.
Now how can you counter it with sound money? We can expect the value of coins to increase by 100% over a year. It did not happen last year and the year before that, but if you look at history, it has been far better, so it is a very real possibility. The volatility is a risk, and you take care of that risk by not having all your savings in crypto.
So how much do you need to have, to counter the risk of inflation of your local currency?
Even with an expected 20% consumer price increase in local currency, You need only 1/5 in crypto.
Example with a save amount of 10000 ZAR:
Local currency down 20% in value: 8000*20/100 = 1600 (you lose that) Crypto 2000 up 2000*100/100 = 2000 (you win that).
Due to all the risk, uncertainty and organic price changes, it is not necessary to find the exact formula.
This example shows that even with a low amount like 20% allocated to crypto, you can completely counter the local currency depreciation.
If you want even less crypto risk, you can diversify between BTC, ETH, BCH, BSV, LTC and ETC, and learn something about those coins too. Or you can have a lower allocation, like 10%, it reduces the risk, for a slighly smaller inflation protection effect.