What is the value of US dollar if backed by Gold?

That value cannot be determined at this time. The question is actually backwards. You must first determine the price of physical gold in an open bullion (physical) market and that is not what exists at present in the west. Paper and paper derivatives are establishing the price point at present (naked shorting) and recently we have seen leverage as high as 500:1. Meaning 500 paper ounces sold for ever one ounce troy available to deliver. Secondly you must have an accurate figure as to the true amount of currency in play e.g. USD around the world. The most recent figure I could find showed only 1.9 trillion in actual paper currency but the digital and debt load with unfunded liabilities are according to some north of 200 trillion. The treasury has cooked the books so hard that only they probably have a handle on the figure and I am not sure they even know how bad the situation is. Then for the coup de grace you have to have a physical audit of your stores of assayed bullion that are titled to the United States and not leased or pledged with nefarious groups.

Here is an article from Bill Holter using charts by Peter Degraaf just to sober you up a bit. There is going to be holy h$%% to pay for what has been done and the players seem to believe that there will never be another Nuremburg in their future. I believe they are wrong about that day of reckoning although I might be persuaded to skip the trial aspects and just move to summary executions for crimes against humanity.