I just took their quiz (again).   

    CATEGORY     ACRES

    FOOD             3.5
    MOBILITY     0.2
    SHELTER     8.9
    GOODS/SERVICES     6.2
    TOTAL FOOTPRINT     19

IN COMPARISON, THE AVERAGE ECOLOGICAL FOOTPRINT IN YOUR COUNTRY IS 24 ACRES PER PERSON.

WORLDWIDE, THERE EXIST 4.5 BIOLOGICALLY PRODUCTIVE ACRES PER PERSON.

IF EVERYONE LIVED LIKE YOU, WE WOULD NEED 4.2 PLANETS.

Note that the biggest "expenditure" in my quiz is my house -- despite its modest size of 1100 sf -- in which I live alone at present.  If I retake the quiz using my boat as my residence (which I hope will soon be the case) and asserting my future lifestyle plan of never travelling by air (as opposed to my current average of 3 hours of air travel per year) and living on a more local and seasonal food supply:

    CATEGORY     ACRES
    FOOD             2.7
    MOBILITY     0
    SHELTER     0.7
    GOODS/SERVICES     0.5
    TOTAL FOOTPRINT     4

IN COMPARISON, THE AVERAGE ECOLOGICAL FOOTPRINT IN YOUR COUNTRY IS 24 ACRES PER PERSON.

WORLDWIDE, THERE EXIST 4.5 BIOLOGICALLY PRODUCTIVE ACRES PER PERSON.

IF EVERYONE LIVED LIKE YOU, WE WOULD NEED 1.0 PLANETS.

I don't swear that these folks' analysis is perfect;  their dietary options are not granular enough to be really descriptive.  but it does suggest that my project of retiring and moving onto my boat (heavily insulated, independent of shore power, less than 400 sf) and adhering more faithfully to a 200-mile diet, will indeed be a substantial reduction of my global footprint, without giving up the foods I like, my internet connection, etc.

you can live very well on 4.5 acres.  or so I think.

The difference between theory and practise in practise ...