Losing Trick Count
The losing trick count indicates the number of tricks your partnership can expect to make in a suit contract.
It only works when you have a trump fit!
If your side has an 8 card trump fit then the losing trick count is more accurate than counting points.
Step 1: Count your losers
1 card suits
A singleton Ace is a winner, every other card is counted as a loser.
2 card suits
In a 2-card suit, the Ace and King are winners, everything else is counted as a loser.
3 card suits
In a 3-card suit, the Ace, King and Queen are winners, everything else is counted as a loser.
4+ card suits
Only the first three cards in any suit are considered as possible losers.
You can think of
Count your losers in all 4 suits
1 spade loser, 1 heart loser, 2 diamond losers and 1 club loser.
total = 5 losers.
Step 2: Add partner's losers
You can make a good estimate of losers based on how many points partner has shown.
For example, an opening bid at the 1-level showing 12 points will have about 7 losers.
6-9 points = 9 losers.
e.g. A simple raise to the 2 level such as 1♥ - 2♥
10-11 points = 8 losers.
e.g. A jump raise to the 3 level such as 1♥ - 3♥
12-14 points = 7 losers.
e.g. An opening bid at the 1-level.
15-17 points = 6 losers.
18-19 points = 5 losers.
20-22 points = 4 losers.
23 points = 3 losers.
North has a minimun opening hand or 7 losers
Step 3: Subtract from 24
Add your losers to partner's losers.
Subtract the total from 24.
The result equals how many tricks you can make.
Your 5 losers + partner's 7 losers = 12
24 - 12 = 12
Your side can make 12 tricks. 6♠ making 6. Nice!
Ace vs Queen adjustment
A32 is obviously stronger than Q32. Adjusting for that will improve your LTC calculations.
Add half a loser for each queen. Subtract half a loser for each ace.
♠A32 is 1 and a half losers
♠Q32 is 2 and a half losers.
South's hand isn't so good. Too many Queens!