The Ethereum Price Calculator
With this simple calculator you can calculate and speculate what price your alt coins could be if ETH were to hit a certain price.
Example:
Go to coinmarketcap.com to get gwei price of your coin. See example below
Using the above example the gwei value would be 262 (to 8 decimal places). So, if the price of Ethereum is $800, gwei value is 262, and your holding is 500,000 then your total holding would be worth $1,048. But you can then change the ETH price to reflect a price you think it might hit in the future e.g. $2,000 which would change the overall value of your holdings.