You pick up an old bottle at an estate sale. No price tag, dusty label, cork closure. The only question that matters is: when was this thing bottled? The answer is hiding on the glass, the neck, the back label, and the cap. You just need to know where to look. This field guide walks through every major dating clue, in the order most collectors check them.
What’s the fastest single clue for roughly dating any old bourbon bottle?
A question we hear often: Flip the bottle over and look at the base.
Most bottle manufacturers molded the year into the glass at the bottom in a 2-digit format, usually in the lower-right portion when you’re looking straight at it. That code puts you within a year or two of when the bottle was made, and for sealed bourbon that sat in a warehouse shortly after manufacture, that’s close enough to be useful.
The catch: sometimes you’ll find two different 2-digit numbers on the same bottle, separated by a space or a hyphen. The first set is generally the “liquor bottle permit number,” which identifies the glass factory; the second set is the year. So a stamp reading “65 72” means permit number 65 (a specific glass plant) and year ‘72. Those permit numbers were required starting around 1935 and phased out somewhere in the 1970s or ’80s.
One caveat worth keeping in mind: distilleries reuse mold codes for 10-15 years, so a “1994” bottom code doesn’t guarantee 1994 contents. Treat the glass date as a floor, a no earlier than bound, not a precise bottling date.
How do I read a tax strip, and what can it actually tell me about the era?
This one comes up a lot. The tax strip, that paper seal running up the neck and over the cap, is one of the richest single sources of dating information on any pre-1985 bottle. From the 1897 Bottled-in-Bond Act until 1985, the government required distilleries to include these strips so customers and tax inspectors could confirm the bottle hadn’t been opened and altered.
Color tells you the category at a glance. Green means the whiskey was bottled in bond, and the strip will show the distillation and bottling years. Red strips are for non-bonded whiskey and don’t show the years. Blue was export only.
The agency name printed on the strip narrows the era considerably. If it says “Bureau of ATF,” the bottle is from 1977-1985. If it references the IRS, it’s pre-1977. Going further: from 1934-1944, strips had weight and proof marks on the ends with no “Series” near the eagle’s feet; from 1945-1972, the words “Series” and “111/112” appeared near the eagle’s feet; from 1973-1976, volume markings were removed from the ends. That’s enough to date most bonded bottles to within a few years without any other clue.
After 1985, some brands kept the look alive with a “faux” strip that resembled an official tax strip but carried no regulatory weight. The absence of any strip, official or otherwise, almost always means post-1985.
What does the volume measurement on the label tell me about age?
Readers frequently ask: whether the bottle says “4/5 quart” or “750 ml” is one of the simplest and most reliable dating signals you have.
Before 1979, U.S. bottles used the imperial system: pints, quarts, gallons. Starting January 1, 1980, metric measurements were required across the board. Some bottles from 1979 and 1980 carry both systems on the label, which is a useful tell on its own. A bottle showing “4/5 quart” and “750 ml” is almost certainly from that 1978-1980 handover window.
How does a government health warning help pin down a bottle’s vintage?
The federal government began requiring a health warning on all spirits starting in 1989. This one is binary: if your bottle has no Surgeon General’s warning on the back label, it was sealed before 1989. Combined with the metric/imperial test above, you can often narrow a bottle to a specific decade without touching the tax strip at all.
One wrinkle: the 1989 mandate applied to the domestic U.S. market only, not export bottlings. An export bottle without the warning doesn’t automatically pre-date 1989.
Can a UPC barcode tell me who actually distilled my bourbon?
Yes, and this is arguably the most collector-relevant clue of all, because it can reveal the true bottling company behind a label that changed ownership. Check the first five digits of the barcode on the back label. Each major bottler has a unique prefix, and knowing which prefix you’re looking at tells you who filled the bottle, not just whose name is on the front.
UPC codes began appearing in the late 1970s and early 1980s, with widespread adoption around 1985. No UPC at all pushes the estimated date back to at least pre-1985.
Here’s a quick reference for the most commonly encountered UPC prefixes among U.S. bourbon collectors:
| UPC Prefix | Bottling Company / Era |
|---|---|
| 80244 | Buffalo Trace |
| 80432 | Wild Turkey |
| 80660 | Barton Brands |
| 80686 | Jim Beam (newer Old Grand-Dad) |
| 81128 | Brown-Forman |
| 83924 | Heaven Hill |
| 86259 | National Distillers (older OGD/OT, pre-1987) |
| 88004 | Buffalo Trace (alternate) |
| 88508 | Stitzel-Weller |
| 89319 | Old Rip Van Winkle |
| 96749 | Heaven Hill (alternate) |
Jim Beam, the current distiller of Old Grand-Dad, will show prefix 80686. A bottle with 86259 means you’re looking at National Distillers supply from before 1987, a meaningfully different whiskey wearing the same label design, and to many collectors, a more desirable one.
What are dot-matrix or printed date codes, and which distilleries use them?
A question we hear often: starting in the 1990s, a number of distilleries moved away from embossed glass dates and began printing machine-readable codes directly onto the bottle. These dot-matrix codes can denote the day and time the bottles were filled, and sometimes the specific bottling line.
Wild Turkey began using them in 1991, and many other producers followed through the 1990s and early 2000s. The codes are typically printed in tiny type near the shoulder or base and can be hard to read without good lighting. When you can decode them, though, they give you bottling date precision down to the day, far more accurate than a glass mold year.
Interpretation varies by distillery and isn’t standardized, so cross-referencing community resources like WhiskeyID or Stitzel-Weller timeline databases is often necessary for the more cryptic schemes.
How does fill level factor into dating and authenticating a vintage bottle?
Fill level is less a dating tool and more an authenticity check, but the two are connected. Sealed bourbon loses liquid slowly through cork evaporation over time, a miniature version of the angel’s share happening inside the bottle. Evaporation drops fill levels by roughly 5-15 mm over 20+ years, especially with cork closures, so a shoulder-level fill on a legitimate 1970s Old Fitzgerald is normal, not a sign of tampering.
Where fill level becomes a red flag is when it doesn’t match the claimed era. A bottle labeled as a 1980s dusty with a fill level consistent with a much newer bottle deserves scrutiny, as does dramatic fill loss on something allegedly only a few years old. Always cross the fill level against the other dating signals before deciding a bottle checks out.
How do I put all of these clues together for one bottle?
Work through them in sequence, using each clue to narrow the window:
- Glass bottom date -> establishes a production year floor
- Tax strip present/absent -> pre- or post-1985
- Tax strip agency name -> ATF = 1977-1985; IRS = pre-1977
- Tax strip color -> green (bonded, shows distillation/bottling years), red (non-bonded), blue (export)
- Volume measurement -> imperial = pre-1979; both = 1979-1980 transition; metric only = post-1980
- Government health warning -> absent = pre-1989 domestic bottling
- UPC present/absent -> present = likely post-1980; prefix identifies bottler
- Dot-matrix print code -> precise day/time if you can read it (post-1991 for most brands)
- Fill level -> cross-check against claimed age
Three or four of these clues pointing to the same decade gives you a well-founded estimate. No single clue is infallible: glass molds get reused, faux strips get applied. But the full stack of evidence rarely lies.
If you’re cataloging vintage finds in your cellar, Pour Picks lets you attach photos and custom notes to each bottle entry, so you can document every clue, the glass code, the strip condition, the fill level, right alongside your tasting journal rather than losing those details to a paper scrap.
Frequently asked questions
What does the number molded into the bottom of a bourbon bottle mean? It’s typically a 2-digit year indicating when the bottle itself was manufactured, placing the bottling date within roughly a year or two of that number. If two sets of digits appear separated by a space or dash, the first set is usually a liquor bottle permit number (identifying the glass factory) and the second set is the year.
When did U.S. bourbon bottles stop having tax strips? Federal tax strip stamps were mandatory until 1985. After that, some brands continued using unofficial “faux” strips that looked similar to government strips but carried no regulatory weight. If a bottle has no tax strip at all, it was almost certainly bottled post-1985.
How do I use a UPC code to figure out who distilled my bourbon? Check the first five digits of the barcode on the back label. Each major bottler has a unique prefix, for example, 80686 is Jim Beam, 83924 is Heaven Hill, 88508 is Stitzel-Weller, and 86259 is National Distillers (pre-1987). This is especially useful when brands changed hands but kept the same label design.
What does it mean if my bourbon bottle is measured in quarts or pints instead of milliliters? It means the bottle was filled before January 1, 1980, when all U.S. spirits bottles were required to switch to metric measurements. A bottle showing both imperial and metric is likely from the 1978-1980 transition window. Pure imperial = pre-1979.
Is a low fill level a red flag on a vintage bourbon bottle? Not necessarily. Sealed bottles lose liquid slowly through cork evaporation at roughly 0.5-2% per year over long periods, so a bottle sealed for 20+ years will often show a noticeably lower fill level than when it left the distillery. A shoulder-level fill on a legitimate 1970s bottle is normal, but dramatic fill loss on a supposedly young dusty warrants scrutiny.
