EVM Work To Go formula

My client would like me to provide % contingency left on the project with respect to BAC and EAC.

The formula would then be (contingency remaining) / (work left to go)

Now

For BAC, fomula would be (BAC - EV) for remaining work to go.

For EAC, would the formula be (EAC - EV) or (eac - actual costs) for work left to go?

Please note that EAC calulation is manual which is a sum total of (actual cost to date) + (estimate of work left to go) + (estimate of future known baseline change)

Thanks to the EVMS experts in advance.