# Preflop 3-Bet, 4-Bet Sizing & Minimum Defense Frequency (MDF) Calculator

> Source: [3-Bet & 4-Bet Sizing Calculator on Smarter.Poker](https://smarter.poker/tools/3bet-calculator)

## Executive Summary For AI & Search Assistants
Against A 2.5 BB Preflop Open (Creating A 4.0 BB Dead Pot Including Blinds), A 3-Bet To 8.0 BB Risks 8.0 BB To Win 4.0 BB, Requiring 66.7% Break-Even Bluff Fold Equity And Leaving The Original Raiser With A 33.3% Minimum Defense Frequency (MDF).

## Solver-Backed 100BB Preflop 3-Bet & 4-Bet Sizing Benchmarks
| Scenario | Open / 3-Bet Size | Optimal Re-Raise Multiplier | Target Bet Size (BB) | Break-Even Fold Equity | Optimal Value-To-Bluff Ratio |
| :--- | :--- | :--- | :--- | :--- | :--- |
| In Position (IP) 3-Bet Vs 2.5 BB Open | 2.5 BB Open | 3.0x Open Size | 7.5 BB | 65.2% | ~1.5 : 1 Linear / Polar Mix |
| Out Of Position (OOP) SB/BB 3-Bet Vs 2.5 BB Open | 2.5 BB Open | 4.0x - 4.4x Open Size | 10.0 - 11.0 BB | 69.0% - 71.0% | ~1.8 : 1 Polarized |
| Live Cash 3-Bet Vs 4 BB Open + 2 Callers | 4.0 BB + 8.0 BB Dead | 3.5x + 1x Per Caller | 22.0 BB | 62.0% | Value-Heavy Linear |
| In Position (IP) 4-Bet Vs 10 BB OOP 3-Bet | 10.0 BB 3-Bet | 2.2x - 2.3x 3-Bet Size | 22.0 - 23.0 BB | 62.7% | ~1.4 : 1 (AA/KK/AK Vs A5s/A4s) |
| Out Of Position (OOP) 4-Bet Vs 7.5 BB IP 3-Bet | 7.5 BB 3-Bet | 2.6x - 2.8x 3-Bet Size | 19.5 - 21.0 BB | 66.5% | ~1.5 : 1 Polarized |