Lets say I go back in time with a wallet full of, say, 150 dollars worth of bills. How far can I be sent back before I reach a point where I'm unlikely to be able to use my money because it looks too different from the current currency to be acceptable? What are the odds that I'll have some 'old' bills that are still in circulation which I could use even if some of my newer bills wouldn't be accepted?

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    $\begingroup$ United States one-dollar bill. The current design dates from 1963. $\endgroup$
    – AlexP
    Commented Jan 3, 2017 at 22:15
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    $\begingroup$ Depends on currency, and on specific bills. $\endgroup$
    – Mołot
    Commented Jan 3, 2017 at 22:16
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    $\begingroup$ Wait, if you went back to 1950 with bills marked 2017, that's clearly not going to work. You can't ever take future demarked bills to before when they were issued. You'd have to get bills from that era (which defeats the intent of the question). $\endgroup$
    – Green
    Commented Jan 3, 2017 at 22:38
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    $\begingroup$ @Green: How many people ever look at the date on currency? I'm assuming US currency here, since the question says "dollars" (yeah, I know some other countries have their own dollars), and the design of those hasn't changed remarkably in at least half a century. Larger denominations have changed a bit: the portraits are off-center, and there have been some pastels & metallic accents added to the basic green, but in a bad light they might well pass. $\endgroup$
    – jamesqf
    Commented Jan 4, 2017 at 3:34
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    $\begingroup$ Doc had a money suitcase in back to the future backtothefuture.wikia.com/wiki/Money_suitcase $\endgroup$ Commented Jan 4, 2017 at 7:50

10 Answers 10


With some planing (buying 20yo money), you can go back to ~1929. Without any, you can only go back to ~1996.

There's a pretty good chance of getting away with it, going as least as far back as 1929, assuming all your bills are from before 1996 (currency redesign), or even better, before 1990 (security thread and microprinting).

If your (large) bills are from after 1996, you outright cannot use them before that - that's when they started putting more color and giant pictures on them, making it look like play money. If there's a number one turning point to be named, '96 is it.

Your odds of getting a modern note past a cashier prior to 1996 are zero. It wasn't the smoothest transition even in '96 (the first significant design change since the 1920s); there was a lot of, wut dis?

Another answer suggests using entirely one dollar notes. I've no source to back this up (and I suspect if there is one, that it'd be treasonous or patent infringement, or some such), but I never remember cash being as crisp and starched as it commonly comes today. I'd bet money that the company that makes the paper, Crane & Co., changed a part of their proprietary process - somewhere in the '90s. Be sure your bills have been well circulated; good cashiers can spot fakes by their feel alone. Laundry it first, literally.

Standardization of Design

The appearance of U.S. banknotes changes greatly in 1929. In an effort to lower manufacturing costs, all Federal Reserve notes are made about 30 percent smaller—measuring 6.14 x 2.61 inches, rather than 7.375 x 3.125 inches. In addition, standardized designs are instituted for each denomination, decreasing the number of designs in circulation and making it easier for the public to distinguish between genuine and counterfeit notes.

Security Thread and Microprinting

A security thread and microprinting are introduced in Federal Reserve notes to deter counterfeiting by copiers and printers. The features first appear in Series 1990 100 [dollar] notes. By Series 1993, the features appeared on all denominations except 1 and 2 [dollar] notes.

Currency Redesign

In the first significant design change since the 1920s, U.S. currency is redesigned to incorporate a series of new counterfeit deterrents. Issuance of the new banknotes begins with the 100 [dollar] note in 1996, followed by the 50 [dollar] note in 1997, the 20 [dollar] note in 1998, and the 10 [dollar] and 5 [dollar] notes in 2000.

The History of American Currency, uscurrency.gov

1928 (source)

enter image description here

1990 (source)

enter image description here

1996 (source)

enter image description here

These are from three different sources, so the colors don't match in the slightest, but I'd have a hard time telling which note is from 1928 or 1990. Between those two dates is a plausible window of opportunity, or thereabouts. In 1996, it's game over. Bills from after which (especially after 2009), you could flash the money at someone while driving by them at 100mph and they'd think you had Monopoly money.

As of 2017, the security features drop down menu for a $100 bill on US Currency's website is subdivided into these dates: 1914-90, 1990-96, 1996-2013, 2013-Present.

2009 (source)

enter image description here

I've seen an 'old' bill once in the past few years. A quick look in my wallet tells me that if I get sent back to before '96, then I'm washing dishes.

I've seen more then a few counterfeit bills in the last few years, and even though I've never been a cashier, I could feel they were fake. If I had to chose between trying to pass a counterfeit note and one from the future, I'd go with the one printed on the real paper, no matter how fundamentally their manufacturing process may have changed.

Bills need to look (basically) the same, and more importantly, feel the same. That's actually their best security feature IMO (or at least it was. Again, prior to 1996...). Go try and get your hands on some of the paper and see how far you get.

Trying to pass old notes can be equally changeling.

I received from my Dad 150 American Dollars about 12 years ago. [...] I tried to change it in a currency exchange in Sydney and the guy didn't change it because the series are old. –Converting Older United States Dollar Bills, Travel SE

Click that link to see 100 and 50 dollar notes from 1988. That's what cash looked like for nearly three quarters of a century.

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    $\begingroup$ Fun fact: when the OSS sent undercover agents into France in WW2, they gave them new money but they needed it to look old, so they had the female agents and analysts carry it around in their bras to soften it. $\endgroup$ Commented Jan 4, 2017 at 16:03
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    $\begingroup$ It would be awesome if this answer includes picture to show the changes in designs (like pre 1929 / 1929-1990 / 1990-1996 / current) $\endgroup$
    – Fabich
    Commented Jan 4, 2017 at 18:06
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    $\begingroup$ @Samuel I've never once looked at the date on a bill. If you handed me or most store clerks a bill that said 2056 on it neither would notice. I think that was his point. $\endgroup$
    – 8bitwide
    Commented Jan 4, 2017 at 18:10
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    $\begingroup$ If you have sufficient time to plan ahead, old currency isn't terribly expensive. On papermoneyguide.com/us_currency_price_guide.php I see prices for \$10 bills of the 1928 series ranging from \$15 to \$34 for "very good" (the lowest quality listed; and for this purpose, lower quality is usually better.) Considering what \$10 in the 1930s was worth in today's dollars, I'd consider that a fantastic bargain. $\endgroup$
    – David K
    Commented Jan 4, 2017 at 19:17
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    $\begingroup$ @Samuel microprinting requires extremely close examination to detect. Before it was invented, nobody would know to look for it in the first place. $\endgroup$ Commented Jan 4, 2017 at 21:41

According to the Federal Reserve, the average lifespan of bills is typically short:

  • 1\$ bill: 5.8 years
  • 5\$ bill: 5.5 years
  • 10\$ bill: 4.5 years
  • 20\$ bill: 7.9 years
  • 50\$ bill: 8.5 years
  • 100\$ bill: 15.0 years

I don't know what the probability distribution is, but I'd say it's highly likely that even if you carry around 150 1\$ bills, only a few are going to have been printed more than a decade or two in the past. Obviously, nobody's going to accept bills printed in the future (I'd assume); they'd appear to be counterfeit. Thus, you're limited more by when the bills were printed than by how old they look.

Now, the dates on 1\$ bills aren't easy to see at a glance. Try to find the date on this image of a 2009 bill:

(source: wikimedia.org)

Image in the public domain.

Most people probably won't notice the date. However, bank tellers will, as might cashiers and others who handle money on a regular basis.

Various commenters have suggested that an exponential distribution is a more accurate representation of age: $$P(a)=\lambda e^{-\lambda a}$$ for some parameter $\lambda$. I'm inclined to trust them; I clearly was not thinking when I suggested a Gaussian distribution. I made the (incorrect) connection of mean lifetime $=$ most probable lifetime.

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    $\begingroup$ OH OH I found the date! Also I think waldo is somewhere behind george washington :P $\endgroup$
    – dsollen
    Commented Jan 3, 2017 at 22:20
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    $\begingroup$ Not all currencies actually 'date' their bills. Would another currency provide better luck? OP only stated the 'worth' after all. $\endgroup$
    – Weckar E.
    Commented Jan 4, 2017 at 11:40
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    $\begingroup$ I'm fairly certain that the age of bills is not normally distributed. On the contrary, I'd assume that the underlying distribution is essentially one of exponential decay, mediated by how long it takes bills from a particular issue date to reach full circulation. $\endgroup$
    – Schmuddi
    Commented Jan 4, 2017 at 12:07
  • $\begingroup$ I'd bet my money on the distribution being geometric. With the advantage that you wouldn't need any other parameter than already given. $\endgroup$
    – The Vee
    Commented Jan 4, 2017 at 12:21
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    $\begingroup$ Absolutely not Gaussian. That would mean the most common age of a bill is 5.8 years. So currently the most common mint date would be 2011, and fewer 2012 bills. And next year (assuming total cash supply remains the same) there will be as many 2012 bills as there are currently 2011 bills. It'll be Geometric/Exponential $\endgroup$
    – Joel
    Commented Jan 4, 2017 at 13:45

The question mentioned the word "bills" specifically, but coins are another matter. They stay in circulation much longer, and it wouldn't take too much effort to find a bunch quarters from 1965 onward (I'm assuming you're talking about American currency). That is the year that the U.S mint stopped using silver to mint quarters and dimes, and switched to a copper/nickel alloy (with a different mixture of copper and nickel sandwiched in the middle). I'm not sure what you had in mind to purchase in the past, but my plan would be to collect old quarters (in the present) dated 1965 to, say, 1970, and then travel back to 1970 and exchange them for "local" currency. Then repeat the process by finding old coins/bills in whatever year you visit, and jump back a few years again.

If you need more money that is feasible with coins, you could head to a hobby shop that deals in coins, as they often have older bills that are in good condition. Obviously you'll pay greater than face value for those. If you want to avoid that hassle altogether, you could carry diamond or gold bullion into the past, and then find a pawn shop.

For a short answer to your question, I'd say 1965 is the earliest feasible year you could travel to, based on the silver coinage issue mentioned above. (You could always buy older coinage, but you'll pay a premium for it).

  • $\begingroup$ gold bullion is a good bet, you can travel to almost any time or place in the past and readily exchange it for a lot of money $\endgroup$ Commented Jan 4, 2017 at 4:20
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    $\begingroup$ @MatthewLock Just make sure you don't land in an era and region where you can't legally own gold. That might cause some... inconveniences. $\endgroup$
    – Luaan
    Commented Jan 4, 2017 at 11:37
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    $\begingroup$ Something else I just thought of... even if you can own gold legally, you'd want to avoid places where you're required to show identification. That could pose even more problems. $\endgroup$ Commented Jan 4, 2017 at 14:58
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    $\begingroup$ @Luaan: Instead of bullion, you wear a lot of gold jewelery, and visit the local pawnbroker as soon as you arrive. $\endgroup$
    – jamesqf
    Commented Jan 4, 2017 at 19:16
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    $\begingroup$ @jamesqf, and hope you don't fall afoul of any sumptuary laws. $\endgroup$
    – Mark
    Commented Jan 5, 2017 at 1:28

If you are form the future, the chances are good that you can produce undetectable counterfeits. So, don’t take “today’s” money, take “yesterday’s”.

You might even consider taking money that is a century or too “too old” and selling it for collector’s value. If you do, gold coins will probably give better returns than banknotes (and be easier to counterfeit).

If you decide on notes, higher denominations will be worth more, and try to make a bunch of them will consecutive serial numbers to increase collector value.

If space is tight, consider postage stamps (a Blue Mauritius sold for$4m in 1993)

Of course, you had better have a good explanation for how you came by such valuable things, so maybe it would be best to stick with counterfeiting notes of the period to which you will be travelling – and scuff them up a bit first; don’t have them look too new.

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    $\begingroup$ You can buy certain currencies for peanuts and take them back to before they became worthless. I am thinking of US confederate currency (although recently these are going up in price as antiques) or any currency that went through hyperinflation like Zimbabwe dollars. So in the case of confederate dollars, pick them up for cheap/free just after that war finished, and sell them now as antiques. $\endgroup$ Commented Jan 5, 2017 at 10:18
  • $\begingroup$ @MarkRipley Bury them somewhere, then dig them up in the future to sell. If you are goning to sell antiques, stuff that is just several years old won't cut it. $\endgroup$ Commented Jan 5, 2017 at 10:57
  • $\begingroup$ @Daerdemandt: Yep, I've thought about that during my fantasies about owning a my own time machine. The problem becomes finding somewhere that you can not only find again 100 years later (the landmarks have been moved!) but that also no one else will stumble across and will not corrode/erode/destroy whatever you are storing. $\endgroup$ Commented Jan 5, 2017 at 11:03
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    $\begingroup$ There are surely much easier / faster ways to make loads of money with a time machine, e.g. sports betting $\endgroup$ Commented Jan 5, 2017 at 13:18
  • $\begingroup$ @BenMillwood Are you suggesting something like what we see in back to the future 2? $\endgroup$
    – user62562
    Commented Jul 2, 2019 at 16:38

This question just has to be about USA currency. It wouldn't make sense in any other country in the world.

Head a little north and look at Canadian money. For instance the $10 bill:




1937 few















The differences are far from subtle. There's no way any of them could pass for real before they were officially released.

The last three aren't even printed on paper. They are plastic, with transparent windows and holograms.

The newest one features someone who, not only isn't royalty or a Prime Minister, is someone who had never been heard of before by most people. And, in case you didn't notice, the bill is printed vertically.

  • $\begingroup$ Of course it's about US currency. That's what happens when half of the countries in the entire world accept your bills. TL;DR: in Canada you'd be SoL by tomorrow, +1 $\endgroup$
    – Mazura
    Commented Jul 4, 2019 at 0:40
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    $\begingroup$ @Mazura It could be about the euro, which the other half of the world accepts. Hint: won’t work if you go back before 2002. $\endgroup$
    – Mike Scott
    Commented Nov 17, 2020 at 6:52
  • $\begingroup$ ...when it had been a tri-party split of Deutsche Mark, pound Sterling and Franc... incidentally, the swap devalued the buying power of British currency in third world countries... $\endgroup$
    – Trish
    Commented Oct 28, 2021 at 13:28

This answer does not contain specific years because those have been covered in other answers already, and i have no knowledge about it anyway.

if the time travelling device is portable (how else would you get back home?) you could do multiple time jumps, preferably you'd use every jump to get to a design change transition era, this way you could potentially go back as far as you want.

While using gold can be easier, this will remove the "benefits" of inflation, unless there are time periods where gold was more expensive than it is today, which should then be your jump objectives.

  • $\begingroup$ Good point about gold being immune to inflation! A fixed amount of gold buys roughly the same amount of goods and services in any era - which is why many people invest in it. $\endgroup$ Commented Jan 4, 2017 at 15:49
  • $\begingroup$ @OscarBravo not exactly: in the early middle ages, gold coin was next to useless for anyone but long-distance or bulk traders due to being too valuable and just about everything in normal trade amounts being paid for in silver coin. $\endgroup$
    – Trish
    Commented Oct 28, 2021 at 13:31

Since the currency is not indicated, I'll assume you mean Euro (fair game, other answers assumed USD).

Currently circulating €5, 10 and 20 banknotes are from the new Europa series, issued in 2013 (€5), 2014 (€10) and 2015 (€20), with higher denominations to follow. Since the new series are visually different, there is no chance of using them before their release.

Assuming you manage to hoard enough old banknotes (they still appear from time to time), or higher not-yet-replaced denominations, they will be good from 1 January 2002, when the currency appeared for the first time in a tangible form.


I'm not sure if it applies in general, but in czech notes and coins there is year of the issue. So we have notes in design of 1993 but issued with 2013 timestamp. Of course, more and more security details are implemented to newer issues.

According to this, you are limitted to the oldest valid banknote or coin you can have.

Suppose you can do several jumps, say, 2000, 1995, 1990,... and there is always a currency with several valid issues.

Let's stay in Prague.

  1. Buy as many notes and coins issued before 2000 and jump to 2001.
  2. Change the money for Deutsche Mark and trade for the oldest notes and coins.
  3. Jump to the year after the one your youngest note/coin was issued.

You can benefit from:

  • Inflation - Todays \$100 has lower value than yesterdays \$100.
  • Different trading rates. You can buy Russian Ruble for 2015's rate and sell them for 2014's rate.

This way you can jump to the origin of money.

  • $\begingroup$ ...and be happy having a hoard of Kauri shells? ;) $\endgroup$
    – Trish
    Commented Oct 28, 2021 at 13:33

There are two barriers: the natural changes and redesigns that the countries do on their notes as people said above and hyperinflation. All hyperinflation events are barriers because they entail new currencies being invented during the attempts to deal with the hyperinflation.


That depends a great deal on how closely people look at the bills. If someone looks at the date on the bill, then even one year before the bills was printed and they're not going to accept it. If you assume people are just looking at the general design, the size of the picture and so on, Mazura gave an excellent answer that I won't bother to repeat. If you assume the person you're trying to pass the money to is just taking a quick glance that, yes, it's green, you could go much farther back.

Seriously, if I was going to go back in time, I think I'd bring something that is not easily dated, like gold bars. Or maybe bring back something that I could sell.

Someone also mentioned that with modern technology, you could probably counterfeit old currency fairly well. If you want to go to 1850, buy an 1850 bill at an antique shop, scan it in, and print off copies on a laser printer. The only hard part would be getting paper that has the right feel. Your counterfeits would probably be good enough to pass the sort of inspection people would make in 1850.


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