This article answers a common fan question with a data first approach. By using closing point spreads as the standard metric we can compare Super Bowl surprises across decades in a consistent, reproducible way. The short answer is that Super Bowl III is still the biggest upset by spread. The rest of this article explains the method, lists the leading upsets with sources, and shows how you can verify the lines yourself.

Super Bowl III remains the largest upset by closing spread, with the Jets beating the Colts while listed around 18 point underdogs.

Closing point spreads offer a reproducible metric for comparing Super Bowl upsets across eras.

Action Network, TheLines, VegasInsider, and Pro-Football-Reference are the primary sources to verify closing spreads and final scores.

Quick answer: which Super Bowl was the biggest upset and why

One-sentence takeaway

Using closing point spreads as the standard measure, the biggest Super Bowl upset remains Super Bowl III, when the New York Jets defeated the Baltimore Colts 16-7 while listed roughly 18 points underdogs before kickoff, a conclusion supported by historical closing line archives Action Network odds history.

That closing spread both quantifies the market's expectation and lets readers compare games across decades, so the rest of this article explains the data, lists the top upsets by spread, and shows how you can verify the lines yourself.

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Why closing spread is decisive

The closing point spread captures the betting market consensus at kickoff and is widely used for historical comparisons because it reflects all public information available up to game time, including injuries and late news, as recorded in odds histories VegasInsider Super Bowl history.

Using closing spreads does not erase context such as a missing starter or extreme weather, but it provides a reproducible numeric yardstick so readers can rank games objectively rather than relying on memory or narrative.

Definition and context: what counts as an upset in this article

Why choose closing point spread

For this ranking, upset magnitude equals the underdog's closing point spread at kickoff, which means a team listed at plus points is being measured by how many points they were expected to be behind at game time.

Closing lines are preferred because they incorporate the full set of pregame information and public wagering, making them the most consistent single metric for historical Super Bowl upset comparisons as compiled in odds histories TheLines Super Bowl odds history. See BetMGM's spread history BetMGM Super Bowl spread history.

Limitations of other measures like seeding or regular season record

Seeding, a team's regular season record, or narrative weight such as a perfect season offer important context but do not replace spread magnitude; these factors help explain why a spread was large or small, yet they do not change the numeric ranking derived from closing lines.

For example, a favored team with a dominant regular season may still be a moderate betting favorite if markets anticipate matchup issues, so looking only at records can mislead about the market expectation.

Core framework: data sources and how we ranked every Super Bowl

Primary sources used

We built the ranking by consulting established odds history compilations and cross checking final scores with official game records, primarily using Action Network, VegasInsider, and TheLines for closing spreads, and Pro-Football-Reference for scores and team names Action Network odds history. OddsShark maintains a betting odds history list OddsShark Super Bowl betting odds history.

Those sources provide consistent closing-line records across the Super Bowl era, which makes it possible to sort games by underdog closing spread and to note ties or near ties when they occur.

How ties and ambiguous lines were handled

If a game showed different closing numbers across archives, we used the majority value or the figure recorded by the most detailed odds history and noted the discrepancy for transparency, and when necessary we flagged the entry for further review against Pro-Football-Reference box scores Pro-Football-Reference Super Bowl history.

Ranking steps were simple: collect closing spreads for every Super Bowl, normalize signs to show the underdog value, sort the list by that value, then add final score and season context to each entry. See the Funded Plays blog for related methodology Funded Plays blog.

Get the data checklist for verifying Super Bowl closing lines

View the data checklist in the appendix and use the listed sources to cross check any closing lines you want to review.

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Top Super Bowl upsets by closing spread: the ordered list

Top 10 ranked by underdog closing spread

Below are the largest Super Bowl upsets ordered by the underdog's closing point spread, with one short note for context for each entry and a source for the spread or summary record.

1. Super Bowl III, 1969 - New York Jets over Baltimore Colts, underdogs by roughly +18, final score 16-7. This game remains the largest upset by closing spread in modern odds histories Action Network odds history. StatMuse records largest point spreads including similar entries StatMuse largest point spreads.

2. Super Bowl XXXVI, 2002 - New England Patriots over St. Louis Rams, underdogs by about +14, final score 20-17. The closing spread reflects preseason perception of the matchup and is recorded in contemporary odds archives TheLines Super Bowl odds history.

3. Super Bowl XLII, 2008 - New York Giants over New England Patriots, underdogs around +12, final score 17-14. This entry ranks high because it ended an otherwise perfect Patriots season and shows the spread magnitude for the upset CBS Sports ranking of big upsets.

4. Super Bowl IV, 1970 - Kansas City Chiefs over Minnesota Vikings, underdogs by roughly +12, final score 23-7. The spread and result are documented in historical odds lists and game summaries TheLines Super Bowl odds history.

5. Super Bowl XXXII, 1998 - Denver Broncos over Green Bay Packers, underdogs by about +11, final score 31-24. Closing-line archives record that Denver was a mid double digit underdog before kickoff VegasInsider Super Bowl history.

6. Other notable entries include Super Bowl LV, where the Tampa Bay Buccaneers were listed around +3 underdogs, and Super Bowls LVII and LVIII, which featured small-line underdog wins that do not approach the historical top tier, leaving the long standing ranking intact into the mid 2020s Action Network odds history.

What was the biggest Super Bowl upset?

Measured by closing point spread at kickoff, Super Bowl III is the biggest Super Bowl upset; the New York Jets beat the Baltimore Colts 16 7 while listed around 18 point underdogs in primary odds histories.

7. Rounding out the top ten are several earlier era games and a few modern surprises where the underdog value reached low double digits; for details on positions six through ten consult the appendix sources where spreads and final scores are tabulated.

Each entry above pairs the underdog closing spread with the final score so readers can see both the market expectation and the actual outcome as archived by the cited sources.

Short notes on each entry

Across the list, games with double digit underdog spreads are rare, and the clear leader is Super Bowl III by the margin of the closing line, which remains the single largest recorded spread upset in Super Bowl history according to the primary odds archives VegasInsider Super Bowl history.

Smaller spread upsets are more common in the modern era but still provide meaningful stories about matchup outcomes and market surprises.

Deep dive case study: Super Bowl III, Jets over Colts

Pre-game expectations and why Colts were heavy favorites

Super Bowl III stands out because the Colts were viewed as an established powerhouse and were heavily favored by the betting market, which set a large closing spread in favor of Baltimore, a fact preserved in odds records and referenced in historical summaries Action Network odds history.

Market sentiment came from the Colts roster and regular season performance, while the American Football League versus National Football League narrative added a perception gap that amplified the spread.

The Jets victory was emphatic in historical terms because an underdog listed around 18 points overcame a substantial expectation gap, and no subsequent Super Bowl has been recorded with a larger underdog closing spread in the primary odds histories.

That numeric gap is what keeps Super Bowl III at the top of spread based rankings, and it is why researchers and oddsmakers commonly cite this game when discussing the biggest Super Bowl surprises.

Other landmark upsets and context: 2002 Patriots, 2008 Giants, and more

Why these games stand out beyond the spread

Super Bowl XXXVI is often called a landmark upset because the Patriots were significant underdogs to the Rams and the game began a new era in which New England emerged as a dynasty, with the closing line around +14 recorded in odds histories TheLines Super Bowl odds history.

Similarly, Super Bowl XLII is culturally significant because it ended the Patriots undefeated regular season and the closing spread near +12 underscores how unexpected the result was at kickoff CBS Sports ranking of big upsets.

Short notes on modern-era championships through 2024-2025

Recent championships through 2024 and 2025 include underdog wins by modest lines, but none matched the double digit underdog magnitude seen in the historical top entries; these modern outcomes are recorded in the same odds histories used for the ranking Action Network odds history.

When a recent Super Bowl produces a narrow-line underdog victory, it adds narrative interest but seldom displaces the established leaders in a spread based ordering.

Reading spreads and context: when a line understates an upset

How injuries, weather, and late news move lines

Closing lines adjust for injuries, weather, and late news, but sometimes the market underestimates an impact or a matchup nuance, so a game can feel like a larger upset than the spread suggests if context on the day favored the expected winner.

Always read closing lines alongside official injury reports and game-day accounts to understand whether the spread fully reflected the true matchup picture, using archival reports and box scores for context Pro-Football-Reference Super Bowl history.

When narrative matters more than raw spread

There are occasions when storylines such as a perfect season, a legendary coach, or a dramatic in-game sequence make a win feel like a seismic upset for fans and media even if the spread was smaller than for other historic surprises.

That subjective impression is valid for storytelling, but for an objective ranking of upset magnitude by numeric measure, the closing spread remains the consistent comparator.

Common mistakes and myths about Super Bowl upsets

Mistaking seeding or regular season record for upset magnitude

One common error is to equate a top seed or a dominant regular season with being a larger favorite in betting markets; those variables can correlate with lines but they are not the same metric and should not be substituted for the closing spread.

Always check the documented closing line when labeling a game the biggest upset, rather than relying on memory of standings or season narratives.

Another myth is thinking that dramatic late comebacks necessarily correspond to large pregame spreads; many close games were expected to be close, so the drama is real yet the pregame market did not label them as massive upsets.

To avoid confusion, separate the emotional weight of a game's story from the numeric measurement of upset magnitude by looking up the closing spread in an odds history archive.

How to verify odds histories and final scores yourself

Trusted online databases to check nfl championship odds

For hands on verification, check closing spreads on Action Network, TheLines, and VegasInsider, and then confirm final scores and official team names on Pro-Football-Reference to reconcile any differences in reporting Action Network odds history. Our homepage offers additional guides Funded Plays.

When sources disagree by a small margin, note both values and prefer the entry that provides a documented closing timestamp or a documented source note, and save screenshots or copies for your records.

Quick cross-check workflow for Super Bowl closing lines

Action Network
TheLines
VegasInsider
Pro-Football-Reference
Screenshot the closing line
Note discrepancies

Save timestamps of sources

If archives show slightly different closing numbers, use the source with the most detailed timestamp or the one that documents market movement and record the discrepancy in your notes, because small differences do not typically alter the top tier of the ranking.

For final confirmation of the outcome itself, always cross-check the official box score and play by play on Pro-Football-Reference, which stores game logs and verified scores.

Practical example: how the ranking would change if you used a different metric

Compare spread ranking to seed-based and Elo-style rankings

If you ranked upsets by seeding or by retrospective Elo-style ratings, a different game might top the list because those systems emphasize season performance or adjusted strength, but they are not capturing the market expectation at kickoff the way closing spreads do.

For instance, a wildcard team that barely made the playoffs but then beat a top seed could be a bigger upset by seeding, while the spread ranking may still show a smaller number if markets expected a close game.

The spread method yields a stable, reproducible historical ordering while alternative metrics highlight different aspects of team strength.

How Super Bowl upsets shaped narratives and betting markets

Media and long-term perception

High magnitude upsets tend to reshape media narratives about leagues and teams, and the memory of a single large surprise can influence public perception for years, affecting how teams are discussed and valued in subsequent seasons ESPN article on big Super Bowl upsets.

That reputational shift sometimes leads to greater market scrutiny and slightly compressed lines in future matchups involving the once underestimated teams.

Markets learn from repeated outcomes, so extreme lines become less common as oddsmakers and bettors refine matchup evaluations, which helps explain why very large single game spreads are historically rare and why Super Bowl III remains notable decades later.

Those market adjustments are gradual and reflect a combination of data, scouting insights, and public response rather than a single causal factor.

Conclusion: final call on the biggest Super Bowl upset and what it means

Summary of evidence

By the closing point spread method, Super Bowl III is the largest Super Bowl upset, with the Jets overcoming roughly an 18 point underdog line to defeat the Colts 16-7, a conclusion supported by primary odds histories and score archives VegasInsider Super Bowl history.

Other notable upsets include Super Bowl XXXVI and Super Bowl XLII, which rank high by spread magnitude and deserve attention for both their market surprise and historical impact.

Final recommendation for readers

Treat the closing spread ranking as a reliable, reproducible measure of upset magnitude, and pair it with game context such as injuries or conditions when forming a narrative or using the result for analysis.

If you want to dig into the raw numbers, consult the sources listed in the appendix and save the closing-line records that matter for your own comparisons.

Appendix: quick reference table and sources to check

Short table layout to include in the article

Suggested table columns: Super Bowl, year, favorite, underdog closing spread, final score, primary source for line. Use the odds histories and Pro-Football-Reference to populate each cell and include a citation for the spread column. See Funded Plays evaluation guide Funded Plays evaluations.

Primary references used for this article are the odds histories on Action Network, VegasInsider, and TheLines, plus official scores on Pro-Football-Reference; additional perspectives on upset significance are available in sport journalism retrospectives TheLines Super Bowl odds history.

How is a Super Bowl upset measured in this article?

Upset magnitude equals the underdog closing point spread at kickoff, which reflects market expectation just before the game.

Why is Super Bowl III considered the biggest upset?

Because the Jets overcame an underdog closing spread of roughly 18 points to beat the Colts 16 7, which is larger than any other Super Bowl underdog spread in odds histories.

Where can I check historical closing spreads myself?

Consult Action Network, TheLines, and VegasInsider for closing spreads, and use Pro-Football-Reference to confirm official scores.

If you want to explore the numbers, use the appendix sources and save the closing-line records relevant to your analysis. Treat spread rankings as one tool among many when crafting narratives or evaluating historic games. For readers interested in skill based sports forecasting rather than traditional wagering, the methodology used here mirrors disciplined, evidence based approaches to historical analysis.