Rule of Fifteen: When to Open in Fourth Seat

Quick Summary

The Rule of 15 decides whether to open in fourth seat. Add your HCP to your spade length, if the total is 15 or more, open; otherwise pass and end the hand.

Why Fourth Seat Is Different

In fourth seat, you can pass out the hand. The question isn’t “Can I open?” but “Should I bother?”

If you open, opponents get a chance to compete. Sometimes it’s better to take your plus zero.

The Formula

HCP + Spades ≥ 15 → Open

Why Spades?

Spades are the boss suit. If opponents compete, having spades lets you outbid them cheaply.

Example Hands

Open (Rule of 15)

♠KJ974 ♥A3 ♦Q85 ♣Q74

HCP: 11 + Spades: 5 = 16 → Open 1♠

Pass (Under 15)

♠74 ♥AQ93 ♦KJ85 ♣Q74

HCP: 12 + Spades: 2 = 14 → Pass

You have points but opponents likely have spades. Pass it out.

The Logic

If you’re short in spades: – Opponents probably have spades – They can outbid you – You might buy a bad contract

If you have spades: – You can compete effectively – Opponents can’t easily steal

Light Fourth Seat Openings

With the Rule of 15, you might open light:

♠AQJ74 ♥93 ♦K85 ♣742

HCP: 9 + Spades: 5 = 14

Close! Many would pass. Others open 1♠.

Heavy Passes

Conversely, you might pass with decent points:

♠7 ♥AQ93 ♦KJ854 ♣Q74

HCP: 12 + Spades: 1 = 13 → Pass

Opening risks a bad result when opponents have spades.

Modifications

Some players use: – Rule of 14 (more aggressive) – Rule of 16 (more conservative)

Or adjust based on vulnerability.

After Passing Out

When fourth seat passes: – The deal is over – No score recorded – Move to next board

No shame in passing out!

What About Other Seats?

Seat	Rule
1st	Normal opening standards
2nd	Normal, maybe lighter
3rd	Light openings OK (preemptive value)
4th	Rule of 15

Key Takeaways

HCP + Spades ≥ 15 → Open
Spades matter, The boss suit
Can pass out, No obligation to open
Short spades = danger, Opponents compete
Adjust to style, 14, 15, or 16

See also: Hand Evaluation (point counting), Passed Hand Bidding (3rd seat light openings)