BlackjackPilot Blog

Simulator Benchmark: Basic Strategy vs I18+Fab4 vs Full Index

Ever wondered whether Full Index is really worth it over I18+Fab4? This post walks through a reproducible 20x1M benchmark, clear tables, and a practical workflow you can run yourself in Custom Strategy.

Published May 7, 2026

Topic: Card Counting

Ever wondered whether Full Index is really worth it over I18+Fab4? This post walks through a reproducible 20x1M benchmark, clear tables, and a practical workflow you can run yourself in Custom Strategy.

Have you ever asked yourself: - "Is I18+Fab4 enough for real play, or does Full Index materially improve EV?" - "Why do two simulations sometimes show contradictory results?" - "How can I compare systems without fooling myself with variance?" This guide answers those questions with a reproducible workflow in the Custom Strategy simulator and a full 20x1M benchmark. It also includes a full measured benchmark using the engine in this project: - 20 seeded runs - 1,000,000 hands per run - Basic vs I18+Fab4 - I18+Fab4 vs Full Index Why most comparisons fail Most A/B comparisons break because the two systems do not see the same random shoes. That makes the outcome a variance story, not a strategy story

BlackjackPilot — Blackjack Strategy, EV & RTP Tools

BlackjackPilot is a blackjack training platform with an AI autopilot, hand tracker, EV/RTP simulator, card counting drills, and Illustrious 18 deviation charts. Practice blackjack strategy, track sessions, and improve your edge.

Practice trainer · EV & RTP Simulator · Strategy Guide · Blog

Blackjack Basic Strategy Chart & Illustrious 18 Deviations

Complete blackjack strategy charts for hard hands, soft hands, and pair splitting. Supports H17 and S17 rule sets, DAS, late surrender, and single/double/multi-deck configurations.

Basic Strategy Overview

Blackjack basic strategy is the mathematically optimal move for every player hand against every dealer up card, given a fixed rule set. Playing perfect basic strategy reduces the house edge to approximately 0.5% or less depending on the rules.

Key rule effects: H17 (dealer hits soft 17) increases house edge by ~0.2% compared to S17. DAS (double after split) lowers house edge by ~0.14%. Late surrender lowers house edge by ~0.07% with correct usage.

Illustrious 18 Deviations

The Illustrious 18 are the 18 most valuable count-based index deviations from basic strategy for the Hi-Lo card counting system. Mastering these 18 index plays recovers the majority of the EV available from all possible deviations.

Hand	Dealer Up	Index	Deviation (vs Basic)
Insurance	A	+3	Take insurance above TC +3
16	10	0	Stand (basic: hit) at TC ≥ 0
15	10	+4	Stand at TC ≥ +4
10,10	5	+5	Split at TC ≥ +5
10,10	6	+4	Split at TC ≥ +4
10	10	+4	Double at TC ≥ +4
12	3	+2	Stand at TC ≥ +2
12	2	+3	Stand at TC ≥ +3
11	A	+1	Double at TC ≥ +1 (H17)
9	2	+1	Double at TC ≥ +1
10	A	+4	Double at TC ≥ +4
9	7	+3	Double at TC ≥ +3
16	9	+5	Stand at TC ≥ +5
13	2	-1	Stand at TC ≥ -1
12	4	0	Stand at TC ≥ 0
12	5	-2	Stand at TC ≥ -2
12	6	-1	Stand at TC ≥ -1
13	3	-2	Stand at TC ≥ -2

H17 Deviation Chart

When the dealer hits soft 17 (H17 rule), the following index plays change compared to S17: double 11 vs Ace becomes correct at TC +1 instead of never, and soft 18 (A,7) vs Ace becomes a double at high positive counts. The H17 rule shifts several indexes by 1–2 points in the positive direction.

S17 Deviation Chart

Under S17 (dealer stands on soft 17), the Illustrious 18 indexes listed above apply directly. S17 is the more player-favorable rule, reducing the house edge by roughly 0.2% compared to H17.

Fab 4 Surrender Deviations

The Fab 4 are the four most valuable surrender index plays. They are only applicable when late surrender is offered: surrender 14 vs 10 at TC ≥ 3, surrender 15 vs 10 at TC ≥ 0, surrender 15 vs 9 at TC ≥ 2, and surrender 16 vs A at TC ≥ -1.

Blackjack EV & RTP Simulator

Simulate blackjack expected value (EV) and return to player (RTP) for any rule set. Compare strategy decisions, run matchup simulations, model bankroll variance, and backtest custom strategy maps.

What is Blackjack RTP?

Blackjack RTP (Return to Player) is the percentage of total wagered money returned to the player over a large number of hands. With perfect basic strategy, blackjack RTP is approximately 99.4–99.6% depending on the rules. This means the house edge is 0.4–0.6%.

RTP is calculated as: RTP = (Total Return / Total Bet) × 100. An RTP of 99.5% means for every $100 wagered, the expected return is $99.50, or a $0.50 expected loss.

Blackjack EV Calculator

Expected Value (EV) per hand in blackjack is the average profit or loss per unit bet, expressed as a decimal. EV = −0.005 means you expect to lose 0.5 cents per $1 bet on average. Card counters can shift EV positive at high true counts.

House Edge by Rule Variation

Rule	Effect on House Edge
H17 (dealer hits soft 17)	+0.22% (worse for player)
DAS (double after split)	−0.14% (better for player)
Late Surrender	−0.07% (better for player)
Single Deck vs 6 Deck	−0.58% (better for player)
RSA (re-split aces)	−0.06% (better for player)

Blackjack Strategy Blog — BlackjackPilot

Practical guides and analysis for better blackjack decisions. Topics include basic strategy, card counting, the Illustrious 18 deviations, soft hands, pair splitting, bankroll management, and EV/RTP analysis.