Acol/Standard American differences
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The Differences between Acol and Standard American


This document outlines the differences between the Acol and Standard American bidding systems. It is written from the perspective of an Acol player who wishes to learn Standard American.


The basics


Both Acol and Standard American are so-called natural systems (as opposed to a system like precision ). But Acol is rather more natural than Standard American. Playing Acol all 1-level openings promise at least 4 cards in the suit (perhaps with the exception of exactly 4333 shape (four 's) when some prefer 1 to opening the 4-card suit). Playing Standard American a 1 or 1 opening always promises at least a 5 card suit, so sometimes 1 or 1 has to be opened with just a 3-card suit.


The other major difference between the two systems is the No Trump structure. In Acol a 1NT opening is 12-14 but in Standard American it is 15-17. This also affects the No Trump rebid range and this is discussed in detail later.


Major Suit Openings

Hand A Hand B With Hand A you might consider opening 1 if playing Acol,

but a weak 1NT is probably best. Playing Standard American

A53 A5 you cannot open 1NT as that's 15-17, and you cannot open 1
AQ65 AQ654 as that guarantees 5 's. So open 1.
65 65 Hand B is a clear 1 opener in either system.
QJ62 QJ62  

Responses to a major suit opening

Hand C Hand D With both of these hands partner has opened 1. Here we see

one of the main advantages of playing Standard American -

1042 J1042 responder knows that opener has a 5 card suit and so can
K98 K98 always happily raise with just three card support.
J9432 J943 With Hand C an Acol player would have to respond 1NT but in
K7 K7 Standard American it's 2. With Hand D an Acol player would
        respond 1 but 2 is better if you know that partner has 5 's.

Minor suit openings

Hand E Hand F With Hand E an Acol player would open 1 and rebid 1NT

(15-16) over a major suit response. In Standard American the

AQ5 J652 best opening is 1NT (15-17).
KJ3 AQ63 With Hand F an Acol player would open 1NT, or otherwise 1
K9432 AQ6 if he is one of those players who does not like to open 1NT with
K7 87 a weak doubleton. A Standard American player has to open 1
        - the better minor, a major suit opening promises 5 cards.

Responses to a minor suit opening

Hand G Hand H With both of these hands partner has opened 1.

With Hand G an Acol player would support with 2, but

J42 42 a Standard American player would have to respond 1NT
J98 K982 as partner may well not have 4 's.
632 632 With Hand H it's the same in both systems bid 1.
AQ76 AQ76  

Responding with a new suit at the two level

Hand J Hand K With both of these hands partner has opened 1.

With Hand J an Acol player would bid a descriptive 2,

42 Q42 but a Standard American would have to bid 1NT because
J98 J98 a new suit at the two level guarantees 11 points when playing
Q32 J3 Standard American.
AQ762 AQ762 With Hand K an Acol player would again bid 2 but in
        Standard American he simply raises to 2 as he knows it's an
        8 card fit and he is too weak for a new suit at the two level.

INT openings and NoTrump rebids


Now I said just now that a new suit response at the two level promises 11+ points when playing Standard American (but only 8+ when playing Acol). Why is that?

Hand L With Hand L you open 1 and partner responds 2. What now?

An Acol player would bid 2, after all, his initial opening promised only 4 's

KJ and partner may well have 3 card support.
K9742 But a Standard American would be loathe to rebid this motley suit and 2NT is best.
Q7 This NoTrump rebid is 12-14 points and that is the reason that responder's two
KJ76 level bid has to be 11+ , because opener may be forced to bid 2NT with just 12
    points or so.

The structure for No Trump bids is as follows: -

  Standard American
  1NT opening
  1 - 1 - 1NT
  1 - 2 - 2NT
  1 - 1 - 2NT
  17-18 (or 17-19)

Two Level Openings


The strong 2 opening is the same in both systems. In America most players play 2// as all weak bids whereas many Acol players will use 2 as something more constructive, such as a Benjamin two opening or a multi two diamonds. There is absolutely no reason why you cannot play either Benjamin twos or the Multi 2 along with Standard American, but very few Americans have adopted the approach. So most Americans make do with just the one strong opening and more advanced Standard American players play 2 waiting and 2 negative responses over a 2 opening.


The 2NT response to an opening bid.


The traditional meaning of the 2NT response to any opening bid is the same in Acol and in Standard American a balanced 11-12 points and no 4 card major. But there are variations:

  In SAYC (a very specific basic variation of Standard American) the 2NT response to 1/ is 13-15 and forcing, but very few players play that. The 2NT response to 1/ is played as Jacoby 2NT by most more experienced Standard American players.  
  A popular treatment for 2NT in the UK is the Baron 2NT, this is probably better than playing 2NT as 11-12 but I would still play Jacoby 2NT over major suit openings.  

A few more minor differences:

Consider these sequences: -
1 - 2 - 2 In Acol this 2 bid is passable. In standard American a two level response promises another bid (unless opener rebids 2NT).
1 - 2 - 3 In Acol this sequence is invitational, but in Standard American the 2 response guaranteed 11+ points and so the sequence is game forcing.
1 - 2 - 2 In Acol this 2 bid is passable. In Standard American it is forcing.
1 - 1 - 1NT - 2 In Standard American this sequence is weak and opener should pass or correct. But playing Acol the 1NT rebid is 15-16 and so opener may decide to press on if he has an exceptionally good hand for 's.
1 - 1 - 1NT - 3 In Standard American the 1NT bid is weak and the 3 bid is invitational. But in Acol the 1NT bid is 15-16 and so 3 is forcing.

You might like to have a look at the is it forcing' document in order to brush up on what's forcing in either system.


There is an advanced variation of Standard American called two-over-one and that is what most experienced players play.

For those of you familiar with Acol I can recommend the book by Sally Brock which assumes a basic knowledge of Acol.
The most popular variation of Standard American, especially for use with casual partnerships on the internet, is SAYC (Standard American Yellow Card). The SAYC book by Ned Downey and Ellen Pomer is excellent and is the only really comprehensive book about SAYC.
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