IMPs in Bridge: What They Are and How IMP Scoring Works

IMPs (International Match Points) are the scoring units of team bridge. On every board you compare your team's score with your teammates' result at the other table, then turn the difference into IMPs on a fixed scale that runs from 0 to 24.

That one rule shapes the whole game. A 30-point overtrick is worth 1 IMP. A vulnerable game that one table bids and the other table misses is worth 10. So IMP scoring rewards you for bidding games and slams and for making your contracts, and it barely notices overtricks. This guide covers what IMPs mean, how a team board is scored, how to work out the IMPs yourself, and how good players change their bidding, play and defense when the scoring is IMPs.

IMP stands for International Match Point. You will see it written IMP, IMPs or imps, and most players say "imps" as one word. When someone says "we are playing IMPs", they mean the scoring is IMPs, not matchpoints.

IMPs are the standard scoring for team events: club team nights, Swiss teams, knockout matches, national trials and world championships. The Bermuda Bowl, the world team championship, is scored in IMPs. Many online team matches use them too, and some pairs games do, as you will see below.

Before IMPs, team matches were often scored by total points: you added up every board and the bigger total won. One wild board, such as a doubled contract going down 1400, could decide a whole match. The IMP scale squeezes big numbers, so a single disaster still hurts but cannot cancel out a full session of good bridge.

Do not mix up IMPs with MPs. MP means matchpoints, the scoring of most pairs games, where only the ranking of your score counts and the size of the win does not.

A team has four players in two pairs. In a match against another team, one of your pairs sits North-South at the first table and your other pair sits East-West at the second table. The opponents do the reverse. Both tables play the same boards, so on every deal your team holds the North-South cards once and the East-West cards once.

After each board:

1. Take your pair's score at your table.
2. Take your teammates' score at the other table. They held the other cards, so their plus score is your team's plus score.
3. Add the two scores. The total is your team's net score on the board.
4. Convert the net score to IMPs on the IMP scale. The other team gets the same number with the sign reversed.

At the end of the match, add up the IMPs on all the boards. The team with more IMPs wins.

Here is a short match. North-South at your table is your pair; East-West at the other table is your teammates.

Your team wins by 4 IMPs (10 - 1 - 11 + 6), even though it lost the biggest board. Look at boards 1 and 3: one game and one slam decided almost everything. The 30-point overtrick on board 2 cost a single IMP.

The World Bridge Federation (WBF) sets the scale. A difference of 0 to 10 points is 0 IMPs, 20 to 40 is 1 IMP, 50 to 80 is 2 IMPs, and the steps get wider as the numbers grow, up to 24 IMPs for a difference of 4000 points or more. The complete table, row by row, is on our IMP scale page.

You do not need to learn all 25 rows. The same few swings come up again and again:

Two things stand out. Overtricks are worth 1 IMP. Game and slam bonuses produce swings of 6 to 17 IMPs. That gap is the reason IMP tactics look the way they do.

To convert a board by hand:

1. Write both scores from your team's side: plus when your side scored, minus when the opponents did.
2. Add them to get the net score.
3. Find the band on the IMP scale that holds the net score, ignoring the sign.
4. Give the IMPs the sign of the net score.

Example: you bid and make 4♠ vulnerable for +620. At the other table the opponents also bid 4♠, your teammates double it, and it goes down one: +200 for your side. The net is +820. That falls in the 750 to 890 band, so your team wins 13 IMPs.

For a faster check, the BridgeDummy bridge score calculator has an IMP converter built in. Type your table's score and the other table's score, each from your side's view, and it shows the swing on the WBF scale. The same page scores any contract at any level, doubled or not, so you can work out "4♠ doubled, down one, vulnerable" first and then convert it.

The scale is lopsided in your favor when you bid a game. Say you bid a vulnerable 4♥ and the other table stops in 3♥. If the game makes, you win 10 IMPs (+620 against +170). If it goes down one, you lose 6 IMPs (-100 against +140). You risk 6 to win 10, so the game pays as soon as it makes more than 6 times in 16: 37.5% of the time.

The same arithmetic gives the famous break-even numbers. Each line assumes the other table stops one level lower and nobody doubles:

This is why IMP players stretch to bid vulnerable games, invite more freely and accept invitations with a good maximum. Not vulnerable, the edge is thinner: a game that is close to a coin flip is still right, but only just. A small slam is a straight 50% decision. A grand slam needs a clear edge, because when it fails you lose the whole small slam bonus as well. Our slam bidding guide shows the tools that help you tell a 50% slam from a 30% one.

You open 1♠ with 15 HCP and five spades. Partner raises to 2♠ and you invite with 3♠. Partner has 9 HCP, four trumps and a doubleton heart, the top of the raise, so vulnerable at IMPs they bid the game.

Count your losers. You have one heart loser (you can ruff your third heart in dummy), two diamond losers, and the ♣K if it sits with East. So the game needs the club finesse: lead a club toward dummy and play the ♣Q when West plays low. On this layout West holds the ♣K, the queen wins, and you score +620.

Now swap West's ♣K with East's ♣3. The same game goes down one, and a double dummy solver agrees: only nine tricks, even though diamonds split 3-3, because the defenders lead clubs before dummy's fourth diamond is ready. So 4♠ is about a 50% game.

Vulnerable at IMPs you need only 37.5%. When the other table stops in 3♠, you win 10 IMPs half the time and lose 6 IMPs the other half, an average gain of 2 IMPs a board. Not vulnerable the same game still shows a profit (6 IMPs won against 5 lost), but a small one.

In the play the same math points the other way. An overtrick is worth 1 IMP. Going down in a game you could have made costs 10 to 12 IMPs, more if the other table made it with an overtrick. So a good IMP declarer spends that overtrick freely as insurance.

Say you are in 3NT vulnerable with nine top tricks. A finesse could give you a tenth, but if it loses the defenders can cash four winners and beat you. At the other table your teammates' opponents make 3NT. Take the finesse and win it: +630 against +600, 1 IMP. Lose it: -100 against +600, 12 IMPs. The finesse would have to work more than 12 times in 13 (92%) to be worth trying. Cash your nine tricks and move on.

This is the whole idea of a safety play: you give up a trick you might have made, to guard against a bad split that would cost the contract. Our safety play guide shows the standard ones, and most of them only make sense at IMPs.

Defenders think the same way. Against a game or a slam, the only question is whether the contract goes down. Giving away an overtrick costs 1 IMP; letting a game make that you could have beaten costs 10 or more. So against 4♠ you lead the card most likely to beat it, even an attacking lead from a king, and you can afford to try for a ruff. Against a partscore the stakes are smaller and a quiet defense is fine.

Two habits pay off at IMPs:

• Attack when declarer has enough tricks. If you can count ten tricks for declarer once dummy appears, a passive defense is too slow. Take your risks now.
• Take the setting trick first. Once you can beat the contract, cash out. An extra undertrick is worth 1 to 3 IMPs; letting the contract make is worth 10.

The opening leads guide covers the standard leads and how the form of scoring tilts the choice.

Penalty doubles of partscores are a poor bet at IMPs. Say the opponents play 2♥ not vulnerable, and at the other table your teammates play 2♥ with the same cards, undoubled. If you double and 2♥ goes down one, you score +100 against your teammates' -50: a gain of 2 IMPs. If 2♥ makes, it scores 470, because doubled it is worth a game bonus: -470 against +110, a loss of 8 IMPs. You need to be right four times out of five. Double partscores when the trumps are sitting badly for declarer and you know it, not because you have a few high cards. Our undertrick penalty table shows how quickly doubled penalties grow.

Sacrifices work the same way. The opponents bid a vulnerable 4♠; you save in 5♥ not vulnerable and go down three doubled, -500. If 4♠ would have made, your teammates at the other table score +620 with those cards: net +120, a gain of 3 IMPs. If 4♠ was going down one, your teammates score -100: net -600, a loss of 12 IMPs. A sacrifice that turns out to be a phantom costs four times what a good one gains. Save at IMPs only when you are sure their game makes and the price is cheap.

In a knockout match the team with more IMPs wins and moves on. In Swiss teams and round robins, the IMP margin of each match is converted again, into victory points (VPs), so a 40-IMP win does not count ten times as much as a 4-IMP win. Many events now use a 20-point VP scale with decimals: a drawn match gives each team 10 VPs, and a big win gets close to 20.

IMPs are also used in pairs games, where there is no single other table to compare with. Two methods are common:

• Butler scoring: your score is compared with a datum, the average score on the board, usually after the highest and lowest results are dropped. The difference converts to IMPs.
• Cross-IMPs: your score is compared with every other result on the board, each difference is converted to IMPs, and the total is averaged.

Many online pairs tournaments are scored in IMPs against a datum, so you meet IMP tactics even without a team. One team form works the other way round: in board-a-match, each board is simply won, tied or lost, and it plays much like matchpoints. For a side by side view of both main forms, see matchpoints vs IMPs.

IMP tactics are easy to agree with and hard to apply when a real hand is in front of you. The fastest way to build the habit is to make IMP decisions many times and see the result each time.

On BridgeDummy, lead and bidding puzzles come in IMP and matchpoint versions. You are South and choose one lead or one call. The hidden hands are dealt hundreds to thousands of times to fit the auction, and every option is solved double dummy on every deal. In an IMP lead puzzle, a lead is graded by how often it beats the contract, which is exactly how you should think about leads in a team match. In an IMP bidding puzzle, each call is graded by the IMPs it gains or loses on average. You get 1 to 5 stars at once, so a habit like "bid the vulnerable game" turns from a rule you read into a reflex you trust.

If the basics of contract scoring are still new, start with bridge scoring: you need the raw scores before you can turn them into IMPs.