ECO Opening Name Lookup: Chess Codes A00–E99

Chess ECO codes are short labels used to classify chess openings. The letter shows the broad opening volume and the two digits narrow the game into a family or branch. Type a code into the ECO Opening Name Lookup to connect the code to a named ChessWorld opening route.

ECO codes work like filing labels for opening positions. A code such as C42 points to the Petrov Defense family, while D40 points to the Queen’s Gambit Declined Semi-Tarrasch area. Enter either code in the lookup tool to see the name, volume and study link.

There are 500 main ECO code slots, from A00 to E99. The five volumes A, B, C, D and E each contain 100 numbered codes. Use the A–E volume map on this page to browse the structure without memorising all 500 codes.

Yes, ECO codes are still useful in databases, PGNs, event pages and opening indexes. They are especially handy when one opening has several names or nearby transpositions. Use the quick lookup chips to translate a code before choosing a deeper opening page.

No, an ECO code is a classification label, while the opening name is the human-readable family or variation. One code can cover a branch rather than one exact board position. Use the lookup result as a route into the family, then follow the linked ChessWorld guide for plans.

Yes, many openings spread across several ECO codes because variations and move orders branch quickly. The Ruy Lopez, Sicilian, Queen’s Gambit Declined, Nimzo-Indian and King’s Indian all cover wide ranges. Use the volume cards to compare neighboring codes before treating a name as exact.

E89 is a King’s Indian Defense Sämisch-family code. It belongs in the late E-volume King’s Indian territory rather than the Grünfeld or Nimzo-Indian. Press the E89 chip in the lookup tool and open the King’s Indian Sämisch route.

E24 is a Nimzo-Indian Defense Sämisch-family code. It usually points to the 4.a3 Sämisch structure where White accepts doubled c-pawns for the bishop pair and central space. Press the E24 chip and open the Nimzo-Indian Sämisch route.

D40 is a Queen’s Gambit Declined Semi-Tarrasch Defense code. A typical route is 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 c5. Press the D40 chip and open the Semi-Tarrasch study route.

D58 is a Queen’s Gambit Declined Tartakower-family code. It sits in the QGD zone where Black often uses ...Be7, ...h6 and ...b6-style resilience. Press the D58 chip and open the QGD Tartakower route.

E20 is the broad entry code for the Nimzo-Indian Defense. The typical route is 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 before the game branches into specific Nimzo systems. Press the E20 chip and compare it with E24 and E42 in the Volume E cards.

E69 is a King’s Indian Defense Fianchetto-family code. It belongs to positions where White uses g3 and Bg2 against Black’s King’s Indian setup. Press the E69 chip and open the King’s Indian Fianchetto route.

B18 is a Caro-Kann Defense Classical Variation code. It belongs to the Caro-Kann family after 1.e4 c6 2.d4 d5 and 3.Nc3 or 3.Nd2 structures. Press the B18 chip and open the Caro-Kann Classical route.

C42 is the Petrov Defense. The base route is 1.e4 e5 2.Nf3 Nf6, giving Black a symmetrical and resilient reply to 1.e4. Press the C42 chip and open the Petrov Defense guide.

Volume A covers flank openings, irregular openings, Dutch Defense territory and some early queen’s-pawn systems. It is the mixed volume where many non-1.e4 mainlines begin. Use the Volume A cards to compare English, Bird and Dutch routes.

Volume B covers semi-open games after 1.e4, especially Sicilian, Caro-Kann, Pirc and Scandinavian systems. The Sicilian occupies a very large part of this volume. Use the Volume B cards to compare B18, B40, B54 and B90.

Volume C covers the French Defense and open games after 1.e4 e5. That includes King’s Gambit, Petrov, Scotch, Italian Game and Ruy Lopez families. Use the Volume C cards to move from C42 into Petrov or C80 into Open Ruy Lopez.

Volume D covers many closed games after 1.d4 d5, including Queen’s Gambit, Slav, Semi-Slav and later Grünfeld codes. That mix is why D40 and D78 belong to very different-looking openings. Use the Volume D cards to compare QGD and Grünfeld entries.

Volume E covers major Indian systems, including Queen’s Indian, Nimzo-Indian and King’s Indian Defense. Important searched codes such as E12, E20, E24, E69 and E89 live here. Use the Volume E cards to separate Nimzo, Queen’s Indian and King’s Indian routes.

The Nimzo-Indian Defense mainly lives in E20–E59. E20 is the broad gateway, while codes such as E24 and E42 point to more specific Nimzo branches. Use the E20, E24 and E42 rows in Volume E to choose the right Nimzo study page.

The King’s Indian Defense mainly lives in E60–E99. E69 points to Fianchetto territory, while E89 sits in the Sämisch-family region. Use the Volume E cards to compare the King’s Indian links.

Queen’s Gambit Declined codes appear mainly through D30–D69, with different branches such as Exchange, Semi-Tarrasch, Tartakower and Orthodox systems. D40 and D58 are two high-value examples. Use the Volume D cards to jump into the matching QGD guides.

The fastest way is to type the code into the ECO Opening Name Lookup box. Use uppercase or lowercase, with or without spaces, and the tool normalises it for you. Try E89, E24 or D40 first from the quick-chip row.

Some ECO codes label a family or branch, not one tiny named sideline. Opening databases may also differ slightly in how they display subnames. Use the ChessWorld study link beside the row to move from the code into practical plans rather than stopping at the label.

Yes, the page filter accepts opening-name text as well as code text. Type Nimzo, Petrov, Caro-Kann, Ruy Lopez, Grünfeld or King’s Indian to narrow the rows. Use the matched study link when you want a full guide rather than just a code label.

After finding the ECO code, open the closest ChessWorld guide and study the plans, pawn structure and typical tactics. The code tells you the neighborhood, but the guide explains what to do over the board. Start with the linked route in the lookup result.

Beginners do not need to memorise ECO codes. It is more useful to learn opening principles, recurring pawn structures and a few reliable systems. Use this page as a lookup reference, then follow the beginner opening links when you want practical study.

Yes, ECO codes can help you understand the opening tag inside a PGN file. The ECO tag is a quick clue to the opening family, but it is not a substitute for reading the moves. Paste or type the code into the lookup box and then open the linked opening route.

Your game’s ECO code can differ from the name you expected because move orders, transpositions and later branch choices change the classification. Flexible openings often reach the same-looking structure by different paths. Use the volume cards to check nearby codes before renaming the game.

No, this page is a fast code-to-name and code-to-route lookup. It helps you identify the opening family and then sends you into a more useful ChessWorld guide. Use the lookup first, then follow the study link for plans and examples.