What is today's price of 15 000 Euro given 15 years ago?
"With no written agreement in place, the ""right"" rate is whatever both parties can agree to. I could argue that I could have invested the money in S&P 500 index funds and made about 9% annually over the last 15 years and the 15,000 would have been over 40,000.  The ""fair"" rate would be whatever rate of return could have been expected from whatever your father would have done with the money otherwise - keep it in a bank account, pay off debt, invest in the market, start a business, whatever.  Your father has the benefit of hindsight to know what would have been a good use of the funds over 15 years. Using the rate of inflation results in effectively a zero-percent loan in real interest terms (meaning no profit was made, just accounting for the time value of money). Both parties need to either decide on an amount or equivalent rate, or decide if squeezing the other for a few thousand Euros is worth the strife." What you are positioning as a loan was not a loan at all. Your father bought something to be delivered in the future. Your aunt does not want to deliver it, so she should buy it back at whatever the current market value is. What is the price that your dad believes her share of the inheritance is currently worth? Is that based on actual appraisals and some sort of objective audit? If so, your aunt doesn't have much of a case. If not, then she could seek an audit to bolster her bargaining position. How much did your aunt benefit from having a place to live for the last 15 years. Was that benefit greater than some larger amount of money at an unknown future date? That's probably why she sold her inheritance 15 years ago. Now that the inheritance looks like it is going to be available soon, she wants to trade back after having enjoyed the use of your father's money. That might be okay, but simply paying back the original sum with inflation, but without interest, doesn't seem fair to your father. She may not be able to afford to give any more than what she is offering, in which case, she might want to consider offering the original sum now and some portion of her inheritance as interest on that original sum. I'm not taking sides in this one. If it were one of my siblings, I'd be inclined to give the benefit of the doubt and take a smaller amount back if I felt that the lesson was learned (and if I felt that he/she would make wise use of my gift to him/her).  I have no idea what your father's current economic situation is, nor am I aware of any other baggage that might influence his feelings about his sister. It's as likely as not that money isn't really what is bothering him, in which case, the amount she repays may have little to do with bridging the divide between them. You might need to ask different questions in the Interpersonal Skills stack if you want to help your father feel better. There's often a legal basis to answer this question. For instance, Austria (guessing from your profile) currently uses a 4% Statutory interest rate. You'll need to dig up not just the actual but also the historical rates. Note that you'll want the non-commercial interest rate - some countries differentiate between loans to businesses and loans to individuals.
When a stock is ask for 15.2 and bid for 14.5, and the last market price was 14.5, what does it mean? It means that the seller wants to sell for a higher price than the last sale while the buyer does not want to buy for more than the last sale price. Or what if the last price is 15.2? The seller is offering to sell for the last sale price, but the buyer wants to buy for less. That's a very interesting article, and something that I hadn't considered, but I have a hard time believing that the value of the dollar is really 1/4 of what it was just 15 years ago. Ounces of gold don't appreciate in ounces of gold, and you can't buy anything with them. Like it or now, gold isn't used as a currency, so its price at this time is primarily dictated by how much more that people expect its value to rise in USD. There are two ways to measure the value of money in the past. 1) As Victor mentioned there are inflation statistics covering the last 100 or so years that value the currency against an ever-changing basket of goods. This is sufficient when measuring general inflation over the period of the hundred years where there is data. This is how it was measured in your example. 2) For older time periods or where a value comparison is required between specific items (particularly where these were not in the basket of goods used for the inflation calculation) Historical records of the price of comparable goods can be used. This is in effect the same as mark to market valuations for illiquid financial instruments and requires poring through records to find the price of either a comparable basket of goods to one that would be used for inflation calculations today or a comparable set of items. An example of this is finding the value of a particular type of house (say a terraced house in London) in the 19th Century compared to the same house today by finding records of how much comparable houses would sell for, on average, then and now. This second measure is also used where the country in question didn't or doesn't keep reliable inflation statistics which may well be true of Colombia in the 90s. This means that there is a chance that this way of estimating Escobar's wealth in today's terms may have also been used. Another notable reason to use this methodology is that (unless you are using exchange rates in purchasing power parity terms) the value of money held in different currencies is different. This is even true today as the value of $1 in INR in India is likely to be higher than the value of a dollar in the US in terms of what you can buy. Using this methodology allows for a more accurate comparison in values where different countries and currencies are involved. If you look at the value as a composite, as Graham seems to, then look at its constituent parts (which you can get off any financials sheet they file with the SEC): For example, if you have a fictitious company with: Compared to the US GDP (~$15T) you have approximately: Now, scale those numbers to a region with a GDP of, say, $500B (like Belgium), the resultant numbers would be: Yahoo! Finance would list it as 3.30 for the 20 year corporate AAA bonds. This is using the criteria from the Wikipedia link you stated in the initial question. It is interesting to consider the Netherlands which is part of the Euro zone. Germany uses 1 and 2 cent coins. Adjacent is the Netherlands where items remain priced to the cent but cash totals are rounded to the nearest 5c so 1 and 2c coins are out of circulation. "Im not sure, but let me try. ""That person"" won't affect the value of currency, after two (or three) years (maybe months), agencies will report anomalies in country. Will be start the end of market.  God bless FBI and NSA for prevent this.  Actually, good ""hypothetical"" question." The biggest factor is: Are you really going to invest the difference? It is easy to say you will now, but unless you have a ton of discipline or some form of automatic investing, that is a hard thing to do in practice. Another consideration is that the 30 year loan will usually cost you more over the life of the loan because of the length of it.  Another option is to take the 30 year loan and pay at the rate you would with a 15. Then you get the benefit of paying it down quickly, but have the flexibility to only make smaller than usual payments in any month where you have a financial emergency and need the extra cash. "I can just get the exact same mortgage in a 30-year version, and just pay it off within whatever year window I choose This is an assumption which often does not come true. The ""advantage"" of a 15 year mortgage is you hopefully never decide you want more toys or to go out to eat and suddenly your mortgage takes 30 years to pay off instead of 15. Plus, if I get a 30-year mortgage then I have a cushion in case I run into major financial hardship. That same cushion can turn into other luxuries. Maybe you want new furniture. ""I won't pay extra on the mortgage this year."" Suddenly it's year 22. This is not a 100% guarantee by any means, but it is something which is relatively likely. Yet everywhere I look I see people online going on about how unwise 30-year mortgages are I read a lot of online financial resources and almost never see this claim." "If there is a very sudden and large collapse in the exchange rate then because algorithmic trades will operate very fast it is possible to determine “x” immediately after the change in exchange rate. All you need to know is the order book. You also need to assume that the algorithmic bot operates faster than all other market participants so that the order book doesn’t change except for those trades executed by the bot. The temporarily cheaper price in the weakened currency market will rise and the temporarily dearer price in the strengthened currency market will fall until the prices are related by the new exchange rate. This price is determined by the condition that the total volume of buys in the cheaper market is equal to the total volume of sells in the dearer market.   Suppose initially gold is worth $1200 on NYSE or £720 on LSE. Then suppose the exchange rate falls from r=0.6 £/$ to s=0.4 £/$.  To illustrate the answer lets assume that before the currency collapse the order book for gold on the LSE and NYSE looks like: GOLD-NYSE   Sell (100 @ $1310) Sell (100 @ $1300) <——— Sell (100 @ $1280) Sell (200 @ $1260) Sell (300 @ $1220) Sell (100 @ $1200) ————————— buy (100 @ $1190) buy (100 @ $1180)   GOLD-LSE Sell (100 @ £750) Sell (100 @ £740) ————————— buy (200 @ £720) buy (200 @ £700) buy (100 @ £600) buy (100 @ £550) buy (100 @ £530) buy (100 @ £520) <——— buy (100 @ £500)   From this hypothetical example, the automatic traders will buy up the NYSE gold and sell the LSE gold in equal volume until the price ratio ""s"" is attained. By summing up the sell volumes on the NYSE and the buy volumes on the LSE, we see that the conditions are met when the price is $1300 and £520. Note 800 units were bought and sold.   So “x” depends on the available orders in the order book. Immediately after this, however, the price of the asset will be subject to the new changes of preference by the market participants. However, the price calculated above must be the initial price, since otherwise an arbitrage opportunity would exist." "What does it mean in terms of share price? Should the share price increase by 15 cents?  No, but you're on the right track. In theory, the price of a share reflects it's ""share"" of time discounted future earnings. To put it concretely, imagine a company consistently earning 15 cents a share every year and paying it all out as dividends. If you only paid 25 cents for it, you could earn five cents a share by just holding it for two years. If you imagine that stocks are priced assuming a holding period of 20 years or so, so we'd expect the stock to cost less than 3 dollars.  More accurately, the share price reflects expected future earnings. If everyone is assuming this company is growing earnings every quarter, an announcement will only confirm information people have already been trading based on. So if this 15 cents announcement is a surprise, then we'd expect the stock price to rise as a function of both the ""surprise"" in earnings, and how long we expect them to stay at this new profitability level before competition claws their earnings away. Concretely, if 5 cents a share of that announcement were ""earnings surprise,"" you'd expect it to rise somewhere around a dollar." You are trying to predict the future currency fluctuations that can't be predicted.  If you know for sure you are moving, convert it directly into Euros in near future rather than take a complicated route. A correction always happens every 10-12 years, but the GDP hasn't been moved because of housing this time, which had never happened before either.  So just a typical correction could happen, like in 1998, and 1988 and the decades before that. You're ignoring inflation. Even if we assume the ECB sticks to its 2% inflation  target, and your salary only rises in line with inflation, you will be saving considerably more in forty years' time than you are today. In fact, an interest rate of 2% and an inflation rate of 2% make the sums exceptionally easy. You need to save €25,000 per year in 2057 euros to be a millionaire by 2057, which is €11,322 in 2017 euros. Challenging, but achievable. Of course, you'll only be a millionaire in 2057 euros, which will be worth less than half as much as a euro is worth right now. At indexmundi, they have some historical data which you can grab from their charts: It only has a price on a monthly basis (at least for the 25 year chart). It has a number of things, like barley, oranges, crude oil, aluminum, beef,  etc.    I grabbed the data for 25 years of banana prices and here's an excerpt (in dollars per metric ton): That page did not appear to have historical prices for gold, though.