Measuring someone's wealth is a complex and often contentious task for any government or charity.
It's not just about a pay cheque - you need to look at standards of living, employment, environment and a huge range of other factors.
But one woman claims to have solved it all.
User DonutCone took to Mumsnet to say her sister has come up with the measure of poverty: a tin opener.
She says she herself has not bought a tin without a ring pull in years and obviously does not own a tin opener. Apparently only poor people buy tins that would need a tin opener.
She would never, ever, consider a tin without a ring pull.
She said 'Wow, I didn't think anyone used a tin opener anymore. I've not used one for years. It's only the Tesco Value crap that doesn't have a ring pull these days. Things have got to be pretty bad if you can't afford decent beans!'
Although, some people saw flaws in the theory. One wrote:
Tell her the artisan pates they sell in Fortnum and Mason food hall definitely do not come with a ring pull.
Branston beans don't come with a ring pull and they are much fancier than Heinz.
And another wrote:
Lidl sell lots of ring pull cans so they are available to those of us who are not posh and moneyed.
One user added:
At food bank we make sure that we make up some packs with all ring-pull cans because some people (i.e. rough sleepers) might not have a tin opener.
But it doesn't end there. The long-suffering sister added:
She was also beyond horrified when she saw my value level shampoo. She had forgotten hers so made me drive her to the nearest town to get some £10 a bottle stuff as there was no way 'that stuff' was going on her head.
This is only the latest of my many, many failures she has pointed out. The fact I had a manual toothbrush....that I only have my hair cut once a year... That DS was in own brand nappies. The list is endless.
She added that her sister is a "snob" and proud of it, and only buys wrapping paper at £3 per sheet.