🎲 Backgammon Notes

Backgame

The best back games are usually considered the 1-3, 2-3, and 2-4.

You should only go all-out for a back game once you have two back points made and are at least 70 pips or so behind in the race.

Read more →

Doubling

Magriel provides a guideline for offering or accepting the cube in a racing situation:

In a long race (about 100 pips) a player should be a minimum of 10 pips in the lead to offer a double, or a maximum of 13 pips behind to accept a double.

Free Drops

Post Crawford — Trailer doubles at the first opportunity. The leader has a free drop at even-away scores (for example, 4a-1a or 2a-1a).

Free Drop Rules

Leader takes when favorite:

• Won the opening roll
• Lost opening roll BUT:
  • Hits in the outfield
  • Points on head
  • Rolls a strong double

The leader drops when the underdog.

At odd-away scores (for example 3a-1a) just take the double as leader.

PRAT

PRAT stands for Position, Race, Threats (+ Gammonish). These factors determine whether to offer, accept, or refuse a double.

1. Position

Which inner board points you have that the opponent does not:

• 5th point = 0.75
• 4th point = 0.5
• 3rd point = 0.25

2. Race

Formula: pips ahead / 16

• 16 pips = 1 point
• 12 pips = 0.75
• 8 pips = 0.5
• 4 pips = 0.25
• 1 pip = 0.0625

3. Threats

Formula: decisive rolls / 9

• ≥ 9 rolls = 1 point
• 8 rolls = 0.88
• 4 rolls = 0.44

4. Gammonish

• 30% gammons = 0.5 points
• 20% gammons = 0.33
• 10% gammons = 0.17

PRAT Decision

• ≥ 2 → Double
• ≥ 3 → Pass

When PRAT doesn't work

• Holding games
• Solved races (use Isight or Keith count)
• Prime vs prime
• Points behind an anchor

If there are any market losers you should double.

Olsen Scale

For the doubler — do you have a clear edge in 2/3 plans?

• Race: clear racing lead (12+ pips)
• Prime: good priming structure?
• Blitz: threatening a blitz?

Threats are mandatory when considering doubling. Priming is special — with a very clear priming edge you can send the cube even without other advantages.

For the taker — do you have at least one good source of counterplay?

• Race
• Prime
• Blitz
• Contact (e.g. holding game — defensive plan, only a factor for the taker)

Seven Red Flags to Drop Cubes

1. Lack of development
2. Hoping to get lucky
3. Too many gammons (at some scores)
4. Crunched board
5. Too much work to do (many back checkers, many blots, etc.)
6. Too many threats (completing a strong prime, etc.)
7. Poor timing

Openings

Reference chart →

Beginner (Michy)

• Most important point is the 5-point
• Make an outfield point
• Fight for a good point
• Break the mountain
• Keep at least 3 checkers on the midpoint
• Double hit is Tiger Play!
• Attacking with 8 checkers is weak (e.g. split when opponent has only 8 checkers)
• Attacking with 10 checkers is strong
• Split against the stripped 8-point
• Split against a prime
• Never split facing a blitzing structure (including 53)
• Hit and split

Intermediate (Michy)

• Making a point is better than hitting loose
• Avoid your opponent's stacked points
• Counter an advanced anchor with an advanced anchor
• Every time you roll an ace, think about slotting
• Make sure you can play a six (pay attention to back checkers)
• The best builder is on your nine point

Advanced (Michy)

• A builder cannot work with only one dice
• Do you feel good about your priming battle?
• Who has the better prime? Who can extend more easily? Who trails in the race?
• Strategy for priming favorite: keep building your prime. Forget about your back checkers.
• Strategy for opponent: split as soon as possible.

Double Tiger Play

Hitting loosely on e.g. 5 and 4:

• You hit two checkers
• 2 blots in your home board ≈ 20 return shots
• Good potential to make inner-board points quickly if you are missed

Bearing Off

• Check the 66 roll
• Spare checkers on separate points
• Try to get a spare on the 5th point

Anchor

• Keep anchor when behind in the race
• Break anchor when ahead in the race
• Break when the opponent is weaker
• When behind, keep anchor until no more building possibilities exist

Pip Counting

The Quadrant Crossover Technique

Guide →

Kangaroo Count

Guide →

First count half-crossovers, then make small adjustments. You can forget about the adjustments if the first part already gives you a big advantage/disadvantage.

Criss-Cross Count

Guide →

Isight Method

Rules for the Isight Method pip count:

1. +2 for more than 2 checkers on the 1 point (3 checkers = +2, 4 = +4)
2. +1 for more than 2 checkers on the 2 point (3 = +1, 4 = +2)
3. +1 for more than 3 checkers on the 3 point (4 = +1, 5 = +2)
4. +1 for empty 4, 5, or 6 points — only if the opponent has at least 1 checker on that corresponding point
5. +1 for each crossover
6. +1 for each additional checker on the board (if bear-off didn't begin, this is 0)

How to use it

1. Calculate the isight count (6 rules above)
2. Add isight count to real pip count = adjusted pip count
3. Divide adjusted pip count by 6
4. Add result of step 3 to your adjusted pip count
5. Calculate opponent's adjusted pip count (without step 3–4)
6. Compare

Doubling rules

• Over 6 pip difference — no double
• 6 or lower — double
• 5 or lower — redouble

Taking rules

• 2 pip difference or higher — take
• Less than 2 — pass

Keith Count

For pure race games — an alternative to Isight.

1. Calculate the Keith count for both players:
   • +2 for more than 1 checker on the 1st point
   • +1 for more than 1 checker on the 2nd point
   • +1 for more than 3 checkers on the 3rd point
   • +1 for empty 4, 5, or 6 point
2. The player on roll increases their count by 1/7 (rounding down)
3. Compare both counts

Doubling rules (doubler's count is higher)

• Over 4 pip difference — no double
• 4 or lower — double
• 3 or lower — redouble

Taking rules

• 2 pip difference or higher — take
• Less than 2 — pass

One-Step / Two-Step Pip Tricks

Take/Pass decision (one step)

1. Remove the last digit from the doubler's pip count
2. Add 2 to that number
3. That is the number of pips you can be behind to take

Example: Doubler has 93 pips, trailer has 104.

• Remove the 3 from 93 → 9
• Add 2 → 11
• You can be 11 pips behind to take. You are exactly 11 behind → Take

Doubling decision (two steps)

1. Calculate the take/pass number as above
2. Subtract 4 pips
3. That is how many pips ahead you need to double

Example: Doubler has 94 pips, trailer has 101.

• Take/pass trick: 9 + 2 = 11
• Subtract 4 → 7
• You must be at least 7 pips ahead. You are exactly 7 → Double

Holding Games

Standard holding game

• You are ahead by at least 14 pips
• Full freedom, opponent has an advanced anchor
• → double/take

Key thresholds:

• Borderline take/pass is 21 pips if there is no gap in front of the advanced anchor
• If you have the 7th point, it is only 12 pips ahead to double
• If there is a gap in front of the anchor, it is a take even if more than 21 pips away
• The more volatility, the more you want to double
• You need to double before pay-now
• Rear point 5 pips away → take
• Rear point 4 pips away → drop

Holding game with a goalkeeper

• Much more contact value for the trailing player
• In early stages, the goalkeeper is very strong
• In early stages there are no points
• There are more gammon chances
• Is the goalkeeper an asset or a liability? If liability → pass

O'Hagan's Law

If you have 25% net market losers and you are in a 50/50 if you don't roll a market loser, then you should double.

Five-Point Matches

Detailed article →

When to double — Race positions

When to double — Blitz positions

4a5a leading, 4a4a: double early. 4a or 5a trailing: double very early.

Jumping a Prime

(Notes to be added)

Random Advice

• Be reluctant to blitz if your opponent has a better board
• Outside points and low inner points do not work well together
• When your opponent has an anchor, concentrate on building blocking points in front of the anchor, not attacking behind it
• When you have the 18th point the 13th is not so important
• Gain time by hitting on the 1st point if the opponent splits their back checkers with 24/18
• Being creative is normally wrong

Take Points in a 7-Point Match

One row = that number is doubling. Top right corner = leader doubles. Bottom left = trailer doubles.

Take point / gammon price given. Gammon price = how much does a gammon hurt? If the gammon price is high and the position has gammons, adjust take points.

Red: abnormally high take point (double earlier / drop earlier). Green: abnormally low take point (wait with doubling / take more).

Good Resources

Glossary