Say I was dropped back in time to the year 1550. I have £1 (or a Sovereign if that's what it would be called) to my name. What would that £1 be worth in modern US$, or what could I expect to buy with that £1?
Edit: Let me reword it a bit. I'm not looking for an exact dollar amount. More like wondering if that £1 would be like $5 today, as in a little pocket money; or would it be more like $500, and be some decent walking around money?
The Economic History Association has this little tool for calculating worth over time.
£1 in 1550 would buy you as much as £346.20 ($432.78) would have in 2015. However, it would represent a much larger percentage of the total monetary wealth at the time, about as much £152,500.00 ($190,640.25) did in 2015. So you would have a hard time buying actual things with your £1.
Depending on how you measure it it will range between what you call walking around money and over $100K.
Trying to compare values over that kind of time period creates all sorts of problems not just because of of changes in amounts and cost of labour and changes in raw materials but fundimental changes in how money was used.
Even the coin itself is going to be problem. A pound at that point would have been viewed as an accounting unit more than an actual thing. A sovereign coin would have been viewed as a store of wealth more than something you would actualy spend. Common currency was silver. Gold had a rather more limited role either as bullion or for international trade.
If you absolutely want some numbers measuring worth will spit some out for you:
For the kind of information you are after I would say that the best idea would be to compare costs of labour, as that might give a better idea of how much money would actually be worth to people and how a sum might be considered by those you encounter.
In 1550, in Southern England, it looks like average gross wages for a labourer outside of London were approximately six pence a day, with eight and a half for a carpenter. This implies that one pound is roughly forty days pay for a labourer. That does not mean it could support a traveller for 40 days, but you could probably eek out subsistence for 40 days and likely help support a family if you already have lodging. This is also a month's pay for a carpenter who one assumes would not be outright struggling but rather earning an actual livelihood.
Obviously the average person would have been a lot poorer with with significantly less purchasing power in 1550, making direct comparisons impossible, but somebody working for forty days at minimum wage in the UK today would expect to earn about £1000.
It will be difficult to find a satisfactory answer to this question because the economies of scale and the amount of human labour required to produce goods has altered so radically over time, particularly pre industrialisation and mass production vs post. Say for the sake of argument that a loaf of bread in 1550 cost you a penny (that's 1/240th of a 1550 pound) and a loaf of bread in 2017 cost £1. Does that mean that a single 1550 pound is worth 240 2017 pounds? No, because the amount of human labour which went into making that bread in 1550 would have been significantly greater, and wages for those producing the goods would also vary significantly according to their skills. It's impossible to make a comparison.