Based on doing the entire
Camino Frances in 2013 and 2014, my experience suggests a daily average of €45 - 50 is closer to reality. I stay mostly in hostals (one-star hotels) instead of albergues whenever possible to reduce the chance of catching something from my fellow pilgrims. Plus, having a private room and bath, with the ability to get your hand wash and drying done in a controlled space is priceless. Besides, I am told that I snore...
I tried the calculator using my known performance experience and it produced a daily average of €32. I suggest that is very much on the conservative end of the actual costs involved.
For planning purposes, I would not plan on less than €40. Following my number of €50 per day gives you more flexibility and choices in food, lodging, ground transport, and buying stuff along the way, including Camino gear you come across that works better than what you started with. This occurred to me both years. In both years, I ended up buying additional fleece, gloves hats, and this year a new sleeping bag. I walked from the last week in April, through the end of May in both years.
Coming from the States, I obtained from my bank a debit card with a chip on it that I can load with money in advance, and top off via computer or by phone while away. I loaded it with US dollars and spend it in Euros. This is how I get funds from cash machines, make purchases, and pay for lodging if plastic is usable. If you live in Europe and already have a cash card with a chip, you are "good to go." Just make sure you have enough money in your current account to cover the budgeted expenditures.
I hope this helps.