Blackmar-Diemer Gambit Accepted: Gunderam Defense

Moves

Black scores

51.4%

About even

Everyone

Loses moreEvenWins more

49.5% won3.6% drawn46.8% lost

Every level and clock · 139K games

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5...Bf5

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Your levelnot setDrag to yours ↔

<100010001200140016001800200022002500+

Win rate by rating

Black’s score peaks in the middle, at 1800–1999.

Score against even	Score	Won	Games
	48.9%	47.5%	3.2K
	48.9%	47.5%	7.5K
	50.7%	49.3%	14K
	51.2%	49.8%	23K
	52.2%	50.4%	28K
	52.4%	50.4%	30K
	51.5%	49.2%	21K
	50.3%	47.9%	12K
Hits hardest	47.5%	44.6%	1.9K

Every clock · Tap a row to set your level.

Is the Gunderam Defense good?

Even for Black, across every level and clock.

Floor 51.1 is the worst score you would still get, 90% confident.

Where it wins · rating × clock

<100010001200140016001800200022002500+Every levelUltraBulletBulletBlitzRapidClassical

Best 53.1% · 1800–1999 rapidWorst 48.3% · under 1000 blitz

Faint, hatched: few games, never the best or worst. –: too few to score. Tap a cell to set your level and clock.

Facing the gambit

Black still scores under 50% against it at 2500+, the highest rating measured.

Average game length

0204060

This line 31All openings 34

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Analyze Blackmar-Diemer Gambit Accepted: Gunderam Defense PositionsSee what each move is worth at your rating, move by move

Methodology

Across every level and clock, the Blackmar-Diemer Gambit Accepted: Gunderam Defense scores 51.4% for Black, with a range running from 51.1% to 51.6% around that figure, from 139K rated Lichess games. Win rate, draw rate and loss rate come from games played September 2023 to August 2026.

How the figures are made

Whose games these are: 139K rated games played on Lichess (2023-09 to 2026-08). The games are Lichess’s and free for anyone to use. What is ours is the reading of them. Last rebuilt September 2026.
Which games we count: Rated games only — nothing casual.
Both players within 200 rating points of each other. A mismatch tells you about the gap, not about the opening.
At least 2 moves played.
A game is filed under White’s rating.
Why every number comes with a range: A number off a few hundred games is a guess. The same number off millions is a fact. The range is what tells them apart, and it is what the lists rank on — so an opening cannot reach the top on a lucky run of forty games. The more games behind a figure, the narrower its range.
What the Floor and Edge at worst are: The Floor is the worst score you would still get, 90% confident: the low end of a figure’s range, not its average. Edge at worst is how far wins run ahead of losses, 90% confident, so above zero, that side wins more than it loses even on a bad day. Each is stated for the rating and clock shown, over the games that reached the position. They are on different scales: a score sits at 50 when the sides are level, an edge at zero.
How much we need before we say anything: An opening page needs 100 games. A figure on it needs 100 games at its rating and clock: short of that the answer reads a wider scope and says so, a table row shows only its count, and a map cell shows a dash. Under 1.0K games a figure is drawn faint, and never leads a list or counts as the best or worst place the line wins. The chaos and trap lists need 500 games overall and 250 games at one rating or clock.