Does anyone know how they calculate a day's worth of travel - is it calculated by distance, by time on the train, or simple by the ticket purchase each day no matter where you go??
A day's worth of travel is a DAY - 24 hours. It can be 1k or 1000K. Or am I missing something in your question?
For a rail pass it is generally 24 hours from midnight to midnight, but there are variations from country to country.
It is rare for railpasses to save you money and convenience these days unless you are riding it lots of high priced long distance journeys.
Where are you intending to use this pass, and for which journeys?
A five day rail pass has five boxes for dates. If you are going to use the rail pass for travel any time in one calendar day, you fill in that date in a box. The exception is the "7 PM rule". If you board a night train after 7 PM, you only need to use one day (the second one) of the pass.
Note, use European numbers. If you make an American '7' (without the crossbar), the conductor could claim it was a '1' and that you had already used a day on the 1st.
And I concur with Nigel. If you know how to find advance purchase deals and all-day regional passes, a rail pass is generally not the best value.
Wow! Almost 30,000 posts between the 3 of you!
Add in mandatory reservation fees on fast trains, limited pass-holder tickets on French trains, full price for couchettes and compartments on night trains. Railpasses may soon join the ranks of travelers checks for has-been travel tools.