Bitcoin Forum

How does one calculate a ratio between MHash/s and Shares? I would like to know how many MHash/s it takes me per share.

You can also use CGminer. It gives you an average accepted shares per minute, per card and total. It would become more accurate the longer it runs.

For "normal" pools they are difficulty 1 shares = 2^32 shares or roughly 4.295 billion shares.

So 4295 / MH per s = seconds between shares.  Remember shares are random.  You will on average find 1 share every 2^32 hashes but in the short run there will be variance.

Likely your next question is hashes per block.  
Share difficulty = 1
Current block difficulty = 1,376,302
It will on average* take 1376302 (difficulty 1) shares to find a block with difficulty 1376302.
1376302*2^32 = 5,911,172,079,419,390 (5.9 quadrillion)

Remember a share is worthless.  It has no value it is just used as a proxy.  Since a miner will find roughly 1 share every 4.3 billion hashes and can't over the long run increase share count without increasing hashing power a pool can use shares as proof of work.  When you submit a share you are proving you did ~ 2^32 hashes.

Now for p2pool it uses variable difficulty.  Currently share difficulty is ~550.  Thus it takes 550 * 2^32 hashes for one share = 2,362,232,012,800 (~2.4 trillion).


* We can only calculate the average since hashes are random.  Swings in # of hashes to solve a block of 10% to 500% of expected value are pretty common.  There have been blocks are short as <1% of difficulty and as long as 11,000% difficulty (and possibly longer or shorter).