Beating the House for the Love of Math

Summary

From Excel to Web: Building a Real-Time Blackjack Card Counting Calculator A couple of years ago, I built an Excel spreadsheet out of pure curiosity. The goal was simple: calculate the exact expected value (EV) and optimal strategy for any blackjack hand, accounting for the current composition of the deck. What started as a weekend project became something more interesting when I realized: this is exactly the kind of software online casinos use internally to detect advantage players. Today, I'm launching Advantage Player — a web-based version that anyone can use to understand the mathematics behind card counting. The Excel Origins The original spreadsheet was built on probability theory and combinatorics. For any given shoe state (number of remaining cards of each rank), it could: Calculate running count and true count (Hi-Lo system) Compute exact win probabilities for hit, stand, double, split Generate complete strategy tables based on current deck composition Track expected value as cards are dealt The math was straightforward but tedious. Excel's array formulas made it possible, but barely. Each cell recalculated probabilities based on hypergeometric distributions. It worked, but it was slow and unwieldy. Why Casinos Care Online casinos don't just track your wins and losses. They track: Bet correlation with true count — Are you betting more when the count is high? Strategy deviations — Are you making plays that only make sense at high counts? Session patterns — Do you leave when the count goes negative? They use software similar to what I built to analyze thousands of hands and identify skilled counters. It's an arms race: players study the math, casinos study the players. The Web Version Challenge Porting this to the web wasn't just about translating Excel formulas to Python. The real challenges were: 1. Real-Time Performance Excel could take seconds to recalculate. A web app needs to respond in milliseconds. Every card dealt triggers: Shoe state update (13 card...