Half of a CS2 match is decided before anyone loads in. The map veto settles which maps get played, who plays on their best map, and which team starts on the side it prefers. If you watch, bet on or analyze matches, it is the first thing to check.
The Active Duty map pool
Competitive CS2 uses a pool of seven maps called Active Duty. Premier matchmaking uses it, and Valve's Major rulebook requires the Majors to use it too. As of October 2026 the pool is:
- Ancient
- Anubis
- Cache
- Dust II
- Inferno
- Mirage
- Nuke
Valve rotates the pool at the start of Premier seasons, usually swapping one map. In January 2026 Anubis came back in for Train, and in July 2026 Cache came in for Overpass. Check the in-game list before you rely on old map stats, and treat results on a newly added map with extra caution.
Seven maps is not a random number. It is exactly enough for every standard veto to finish with no maps left over: a best-of-three uses four bans, two picks and a decider, and a best-of-five uses two bans, four picks and a decider.
How a BO3 veto works
This is the order in Valve's Major rulebook. The higher seed first chooses whether to be Team A, which acts first, or Team B.
| Step | Team | Action |
|---|---|---|
| 1 | Team A | Removes a map |
| 2 | Team B | Removes a map |
| 3 | Team A | Picks map 1 (B picks side) |
| 4 | Team B | Picks map 2 (A picks side) |
| 5 | Team B | Removes a map |
| 6 | Team A | Removes a map |
| 7 | Team B | Picks side on the decider |
Map 1 is Team A's pick and map 2 is Team B's pick, so each team gets to play one map on its own terms. The order flips in the second round of removals: Team B removes first, then Team A. That round is where strategy shows, because teams use it to take out the opponent's strongest remaining map, which decides what the decider will be. Team B then chooses the starting side on the decider. There is no knife round.
Other organizers (ESL, BLAST, PGL and others) write their own rulebooks for their own events, and some use a different order, a coin toss, or a knife round on the decider. Liquipedia's event page usually states the format, so check it for the event you are looking at.
How a BO1 veto works
A best-of-one has no picks in the usual sense. The teams remove maps until one is left, and that map is played. With seven maps that means six removals. At a Major they are split like this:
| Step | Team | Action |
|---|---|---|
| 1 | Team A | Removes 2 maps |
| 2 | Team B | Removes 3 maps |
| 3 | Team A | Removes 1 map |
| 4 | Team B | Picks starting side |
Each team removes three maps, but Team B gets the side choice on the map that is left, and there is no knife round. Other events may alternate one map at a time or use a knife round for sides, so read the event rules for the exact order.
Because nobody actively chooses the final map, BO1s often land on a map that both teams tolerate rather than one either of them loves. A team with a deep map pool benefits most from this. A team that only has two strong maps can see both banned and end up on its weakest ground, which is one reason BO1s produce more upsets. The BO1 vs BO3 guide puts numbers on that.
How a BO5 veto works
Valve's published Major rulebook only covers best-of-one and best-of-three, but some grand finals are played as best-of-five, including those of the StarLadder Budapest Major 2025 and the IEM Cologne Major 2026. With seven maps, a best-of-five uses two removals and four picks, and the last map is the decider. The exact order and who chooses sides vary by event, and some events give the team coming from the upper bracket an advantage, such as a one-map head start. Check the event rules or Liquipedia first.
Who chooses the starting side
- On a picked map: the team that did not pick the map chooses whether to start on CT or T. It is the trade-off for letting the opponent choose the map.
- On a BO3 decider: at a Major, Team B chooses. Some other events use a knife round, with the winner choosing.
- In a BO1: at a Major, Team B chooses after the last removal. Other events vary, and some use a knife round.
Side choice matters because many maps lean toward one side. In CS2's MR12 format each half is only 12 rounds, so a strong first half on the favored side can put a team close to the 13 rounds it needs.
How to read a veto like an analyst
- Know the permabans. Most teams ban the same map in almost every series. Once you know both teams' first bans, the rest of the veto is easy to predict.
- Separate picks from comfort. A team's most-picked map is not always its best map. Check its win rate on that map against similar opponents, not just how often it plays it.
- Watch for map pool changes. When Valve rotates a map in, teams take months to build it up. Results on a new map are noisier than on long-standing ones.
- Roster changes reset the data. Map stats from before a roster change describe a different team. Look at matches since the new lineup only.
- Sample size matters. A 5-1 record on a map is six results, not a pattern. Treat anything under about ten maps with caution.
HLTV shows the veto on every match page and keeps map win rates, pick rates and ban rates for each team. Our roundup of CS2 stats websites covers where else to find this data.
How vetoes affect betting
Match winner odds are set before the veto, so they price in a guess about which maps will be played. Once the veto is public, map winner, handicap and total maps markets reprice. That creates two situations worth knowing:
- Predictable vetoes: if both teams always ban the same maps, the pre-veto price already reflects the likely maps. There is little to gain by waiting.
- Uncertain vetoes: when a team has recently changed its permaban, or a new map entered the pool, the veto carries real information. Waiting for it before betting map markets can be worth more than a slightly better early price.
If you bet maps, convert the odds and compare them with your per-map estimate before placing anything. The odds guide shows how. Our methodology page explains how the picks on today's board are made: they come from SkinBetHub's proprietary signal model, built on prediction-market data, are posted with their odds before the match starts, and are graded at a flat 1 unit, with every result kept on the results page.