When we see gain percentage numbers like: +7.01% (24h), -0.43% (7d), +31.33% (30d), and so on, how are they usually calculated? For example for the 7d period, is it calculated using:

([average price for today] - [average price 7 days ago])/[average price for 7 days ago]
  • Probably that formula, but today's closing price and the old date's opening price.
    – RonJohn
    Dec 14 '17 at 7:43
  • But after reading this link, they might use geometric mean instead. Try, and tell us what you found!! :)
    – RonJohn
    Dec 14 '17 at 7:50
  • Geometric mean makes more sense if we are averaging growth rates. If we are averaging price, then arithmetic price makes more sense. Dec 14 '17 at 8:39

If by "average" you mean time-average, then no. That stuff is not correct. The formula in each case is exactly the same

% Gain = (Price at the end)/(Price at the beginning) - 1

If these are gains as of now, then "price at the end" is the current price and "price at the beginning" is the price at the beginning of the period (either 24 hours ago, or 7 days ago, or whatever). Any dividends paid out will complicate the computation as there are a few ways people might treat these.

The concept of "average" can arise if we are talking about the gains on a portfolio instead of on an individual asset. In that case the gains can be computed asset-by-asset and then a weighted average computed using the portfolio weights at the beginning as weights.

Your question has no info about your situation, so let me know if you require more detail or if this is some kind of special case.

  • I'm specifically referring to the gain numbers shown on cryptocurrency exchanges. If what you're saying is true, then 3mo or 1y gain will be as volatile as a 1h gain. One would (at least I would) expect that for 3mo or 1y period, the gain is "averaged" somehow. Dec 20 '17 at 6:02
  • Can you please provide a link to an exchange providing gain numbers that do not conform to the standard gain calculations I have illustrated? It may be that they are annualizing gains or simply doing nonstandard calculations.
    – farnsy
    Dec 20 '17 at 14:56
  • That simplified formula really made my day. I always tried and kept on forgetting the other convoluted formula of [ NewValue - OldValue ] / and that's the part I kept forgetting OldValue. I just never remembered if you had to divide by OldValue or NewValue. But now it's not an issue anymore :)
    – Wadih M.
    Feb 10 '18 at 17:54

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