Open any serious currency error reference and the butterfly cut will earn its own chapter. These are the notes that stop people cold at a show table, the ones that get photographed and passed around before anyone asks the price. Two notes, still joined at a fold, fanning outward like wings from a single crease point. The image is immediately arresting even to someone who has never collected a day in their life. But beneath the spectacle lies a surprisingly technical story about high-speed intaglio printing, sheet architecture, and the razor-thin margin for error inside the Bureau of Engraving and Printing’s finishing operations. Understanding how butterfly cuts form, how to authenticate them, and how to build a meaningful collection around them separates the casual observer from the serious student of error currency.
How the Bureau of Engraving and Printing Cuts Its Notes
To appreciate exactly where a butterfly cut error enters the production chain, it helps to walk through the BEP’s finishing process from start to finish. Since the mid-1990s, the BEP has printed Federal Reserve Notes on large 32-subject sheets. Each sheet measures roughly 21.25 by 45.25 inches and carries four columns of eight notes. After face printing (intaglio), back printing (intaglio), and the serial number and seal overprinting (letterpress), these sheets travel to the cutting room.
The cutting sequence proceeds in two primary steps. First, a cutting machine slices the 32-subject sheet into four horizontal strips, each containing eight notes arranged in a single row. Second, the guillotine cutter divides each strip into individual notes by making seven cuts across the strip’s length. It is during this second set of cuts that a butterfly error can occur. If the blade does not fully complete a cut, or if a note folds back on itself just as the blade descends, the adjacent note pair remains attached at a thin uncut margin. When handled or examined, the joined pair naturally fans open along the fold point, creating the distinctive butterfly silhouette.
The fold point itself is the key diagnostic feature. On a genuine butterfly cut error, the crease runs perfectly parallel to the note’s short axis, landing along what would have been the cut line. Both notes carry all overprinting (serials, Treasury seals, Federal Reserve seals, and district numerals) in their correct positions, because the error happens after all printing stages are complete. This distinguishes butterfly cuts from pre-cutting paper folds, which produce a different and separately cataloged class of error.
Always examine the fold crease under magnification before purchasing a butterfly cut. The crease on a genuine error will show the characteristic fiber compression of a mechanical fold under cutting pressure, not the soft, gradual crease of paper folded by hand. A folded note that was simply never spent is not an error and has no premium value.
Anatomy of the Butterfly: What Both Notes Should Show
A complete butterfly cut error consists of two full-face notes joined along one edge. Depending on which cut failed, the two notes will share either a left-right relationship (joined along vertical edges) or a top-bottom relationship (joined along horizontal edges), though the left-right configuration is by far the more commonly encountered type on 32-subject sheet production.
Both notes in the pair should display full serial numbers, complete Treasury and Federal Reserve seals, and correct positioning of all printed elements. The joined margin will retain a thin strip of uncut paper that ranges from near-microscopic to a millimeter or two wide. Paradoxically, a very clean fold with minimal residual paper at the join can actually indicate a more severe cutting failure, where the blade entered but did not exit the sheet, rather than one where the blade skipped the cut entirely.
Serial numbers on the two notes in a butterfly pair will be consecutive or near-consecutive within the same printing run. On Series 2006 and later notes, where the BEP’s LEPE (Large Examining and Packaging Equipment) system performs automated inspection, butterfly cuts that clear the system represent genuine failures in the optical scanning process, which makes them rarer than equivalent errors from earlier series.
Series and Denominations Most Frequently Encountered
Butterfly cut errors appear across all denominations from $1 through $100, though the frequency of confirmed specimens in the collector market is heavily skewed toward lower denominations. The $1 Federal Reserve Note accounts for the largest share of known butterfly cuts simply because it is produced in the greatest volume. Series 1995, 1999, 2001, 2003, and 2003A $1 notes have all yielded confirmed butterfly examples, with Series 2003A Washington notes from the Dallas and Atlanta districts accounting for a notable cluster of authenticated specimens that appeared at auction between 2008 and 2015.
The $5 and $10 denominations offer some of the most visually compelling butterfly examples because the notes’ green and orange color schemes create an especially striking visual contrast when the pair is displayed open. Series 2006 and 2009 $5 Lincoln notes in butterfly configuration have sold for between $900 and $2,400 depending on grade, with PMG 64 EPQ and PMG 65 EPQ specimens commanding the strongest premiums at auction.
Higher denomination butterfly cuts are genuinely rare. Confirmed $50 butterfly pairs from Series 2004A and 2009 have sold for over $3,500 in AU to Uncirculated grades. Authenticated $100 butterfly cuts from the Series 2009A redesigned notes are among the most prized modern error currency in existence, with auction records above $6,000 for PMG 65 EPQ examples. Dealers such as Lyn Knight Currency Auctions and Stack’s Bowers have handled the highest-profile of these sales.
When a seller lists a butterfly cut error without a third-party grading holder from PMG or PCGS Currency, request high-resolution images of both notes’ serials, seal positions, and the fold crease before committing. Sellers occasionally misidentify a naturally folded pair of circulated notes as an error. Third-party certification eliminates this ambiguity entirely and strongly supports resale value.
Star Note Butterfly Cuts: The Ultimate Rarity Combination
Among advanced collectors, the intersection of two desirable error types in a single note is the benchmark of a truly exceptional piece. A butterfly cut pair where one or both notes carry star serial numbers represents exactly this intersection. Star notes are printed as replacements for notes destroyed during quality inspection, and they are produced in substantially smaller quantities than standard serials. The odds of a star note surviving the inspection process and simultaneously escaping the cutting stage in a butterfly configuration are extraordinarily low.
Known examples of star-note butterfly cuts are handful-level rare. A confirmed Series 2003A $1 star note butterfly from the Federal Reserve Bank of Minneapolis (Minneapolis star runs for that series were already small, typically under 3.2 million notes) was authenticated by PMG in 2017 and sold privately for a reported price in the $4,500 range. Collectors who focus specifically on this intersection should monitor auction archives carefully and expect to wait years between opportunities.
Authentication: Separating Genuine Errors from Clever Fakes
The butterfly cut occupies an awkward position in the error currency world because it is, at its most basic level, two notes that were not fully separated. This means that creating a convincing counterfeit butterfly, by gluing or adhering two genuine notes together, is theoretically possible. Several techniques help collectors and authenticators distinguish genuine mechanical errors from assembled fakes.
First, examine the paper fibers at the fold under a loupe or stereo microscope. A genuine mechanical fold from the cutting process will show compressed, stressed fibers running perpendicular to the fold axis. The surface of the fold will often show very slight ink abrasion from contact with adjacent sheets in the stack. Second, look for any adhesive residue under ultraviolet light. Federal Reserve Note paper does not fluoresce significantly under UV, so any adhesive used to join two notes will often appear as a brighter or darker band across the fold line. Third, the thickness of the paper at the fold point should be consistent with a single sheet folded back on itself, not two separate sheets pressed together, which would measure approximately twice the single-note thickness when folded flat.
Federal Reserve Note paper is manufactured by Crane Currency to precise specifications, including a thickness of approximately 0.10934 millimeters per note. If you have access to a digital micrometer, measuring the fold point of a claimed butterfly cut and comparing it to a folded reference note can provide a quick first-pass authentication check. A genuinely folded single sheet will measure approximately 0.22 mm at the fold; two glued notes together will measure closer to 0.32 to 0.34 mm.
Grading Considerations Specific to Butterfly Cuts
Third-party grading services assess butterfly cut errors using standard grading criteria (centering, surface preservation, fold quality) applied to both notes simultaneously. PMG and PCGS Currency will assign a single grade to the pair, reflecting the overall quality of the joined specimen. Because the fold itself is an intrinsic feature of the error, graders do not penalize the fold crease when evaluating a butterfly cut. However, any additional handling folds, corner bends, soiling, or ink smears outside the error fold will affect the grade.
The EPQ (Exceptional Paper Quality) designation from PMG carries particular weight with butterfly cut errors because it confirms that the paper remains bright, crisp, and unaltered beyond the error itself. Collectors consistently pay a premium of 20 to 35 percent for EPQ-designated butterfly cuts compared to identically graded non-EPQ examples of the same series and denomination.
Both PMG and PCGS Currency use oversize holders for butterfly cut pairs when the notes must be displayed in their fanned configuration. Some butterfly cuts that fold perfectly flat will fit in a standard currency holder, though most collectors specifically request the oversize holder to preserve the dramatic visual presentation of the open butterfly position.
| Series / Denomination | District or Variety | Approx. Known Examples | Rarity |
|---|---|---|---|
| Series 2003A $1 | Atlanta, Dallas (standard serial) | 20-40 confirmed | Scarce |
| Series 2003A $1 | Minneapolis (star serial) | 2-4 confirmed | Key Date |
| Series 1999 $1 | Multiple districts | 15-30 confirmed | Scarce |
| Series 2006 $5 | Various districts | 10-20 confirmed | Scarce |
| Series 2009 $5 | Star note pair | Fewer than 5 confirmed | Key Date |
| Series 2004A $10 | Various districts | 8-15 confirmed | Rare |
| Series 2004A $50 | Various districts | 4-8 confirmed | Rare |
| Series 2009 $100 | New design (blue ribbon) | 2-5 confirmed | Key Date |
| Series 2017A $1 | Various districts (post-LEPE) | 5-10 confirmed | Rare |
| Any series $20 (post-2004) | Standard serial | 6-12 confirmed | Rare |
Building a Butterfly Cut Collection on Different Budgets
Entry-level collectors can find certified $1 butterfly cuts from Series 1995 through 2003A in the $400 to $700 range at major currency shows and through established online dealers. These notes are well-documented in the error currency literature, straightforward to authenticate when certified, and visually dramatic in any collection format. Buying certified from PMG or PCGS Currency is strongly recommended for anyone at the beginning stages of error collecting, as it eliminates authentication risk entirely.
Mid-range collectors working with $1,000 to $3,000 per acquisition should focus on $5 and $10 butterfly cuts in high grade with EPQ designation, or on $1 butterfly cuts that carry additional interest such as low serial numbers, star serials, or particularly clean creases with sharp, unhandled surfaces. The combination of multiple desirable attributes compounds value reliably in this segment of the market.
Advanced collectors and investors pursuing $3,000-plus acquisitions should set alerts on auction platforms for $50 and $100 butterfly cuts, and should actively cultivate relationships with dealers who specialize in high-grade currency errors. Auction houses with dedicated paper money sales, particularly Heritage Auctions’ Currency Signature Sales, Stack’s Bowers, and Lyn Knight, handle the rarest butterfly examples and maintain searchable archives that allow serious collectors to track sale prices over time.
Displaying and Storing Butterfly Cut Errors
The physical format of a butterfly cut creates storage challenges that standard single-note currency supplies do not address. For certified examples in PMG or PCGS oversized holders, standard slab storage boxes designed for large holders work well. For raw (uncertified) butterfly cuts, specialized currency sleeves measuring at least 7.5 by 7 inches are necessary to accommodate the open fan configuration without forcing the notes flat and adding handling wear.
Many collectors choose to display butterfly cuts vertically in display cases rather than storing them flat, both because the fanned configuration is the most visually impressive presentation and because vertical display on archival backing minimizes stress on the fold crease over time. Avoid any display method that requires the fold crease to be flattened under weight, as repeated compression and relaxation of the fold will eventually weaken the paper fibers at that point.
Conclusion: A Error Class Worth the Investment of Attention
Butterfly cut errors combine visual drama with genuine mechanical rarity in a way that few other currency error types can match. They are not the most common errors in the marketplace, nor are they the most esoteric, but they occupy a distinctive middle ground where serious numismatic significance meets immediate visual impact. Whether you are building your first error currency collection or adding a centerpiece to an advanced holding, a certified butterfly cut from a high-denomination modern Federal Reserve Note represents one of the most compelling acquisitions available in today’s market. The key is patience, authentication discipline, and a clear understanding of which series and configurations carry the strongest long-term collector demand.
