I used to have all of the SAE Standard Wrench sizes memorized and could tell you instantly what size was next in order from small to large and which metric socket or wrench was equivalent. That was decades ago, back in my days as a mechanic and technician.

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In the years since, I've completely forgotten where some of the most common box end, open end wrench and socket sizes fit in. After a quick search yielding no real good results containing all of this information, I've decided to create a reference SAE (inches) + Metric (mm) page and size chart for myself and others to refer to. So without further ado, here are the results.

Table of Contents

## Standard Wrench Sizes and their Metric equivalents

Below is a list of commonly used SAE (Imperial) Standard and Metric wrench and socket sizes in ascending order up to 2 inches. For each size, I also mention one size smaller (step down) and the next size bigger or larger (step up), along with their equivalent size in Metric or mm.

**Standard Wrench Sizes in Inches (Smaller than), (Larger than), (Equal to in MM)**:

- 1/4" (1/4" is one size smaller than 5/16") (5/16" is one size bigger than 1/4") (Equal to 6.35 mm in Metric)
- 5/16" (5/16" is one size smaller than 3/8") (3/8" is one size bigger than 5/16") (Equal to 8 mm in Metric)
- 3/8" (3/8" is one size smaller than 7/16") (7/16" is one size bigger than 3/8") (Equal to 10 mm in Metric)
- 7/16" (7/16" is one size smaller than 1/2") (1/2" is one size bigger than 7/16") (Equal to 12 mm in Metric)
- 1/2" (1/2" is one size smaller than 9/16") (9/16" is one size bigger than 1/2") (Equal to 13 mm in Metric)
- 9/16" (9/16" is one size smaller than 5/8") (5/8" is one size bigger than 9/16") (Equal to 15 mm in Metric)
- 5/8" (5/8" is one size smaller than 11/16") (11/16" is one size bigger than 5/8") (Equal to 16 mm in Metric)
- 11/16" (11/16" is one size smaller than 3/4") (3/4" is one size bigger than 11/16") (Equal to 18 mm in Metric)
- 3/4" (3/4" is one size smaller than 13/16") (13/16" is one size bigger than 3/4") (Equal to 20 mm in Metric)
- 13/16" (13/16" is one size smaller than 7/8") (7/8" is one size bigger than 13/16") (Equal to 21 mm in Metric)
- 7/8" (7/8" is one size smaller than 15/16") (15/16" is one size bigger than 7/8") (Equal to 23 mm in Metric)
- 15/16" (15/16" is one size smaller than 1") (1" is one size bigger than 15/16") (Equal to 24 mm in Metric)
- 1" (1" is one size smaller than 1-1/16") (1-1/16" is one size bigger than 1") (Equal to 26 mm in Metric)
- 1-1/16" (1-1/16" is one size smaller than 1-1/8") (1-1/8" is one size bigger than 1-1/16") (Equal to 27 mm in Metric)
- 1-1/8" (1-1/8" is one size smaller than 1-1/4") (1-1/4" is one size bigger than 1-1/8") (Equal to 29 mm in Metric)
- 1-1/4" (1-1/4" is one size smaller than 1-5/16") (1-5/16" is one size bigger than 1-1/4") (Equal to 32 mm in Metric)
- 1-5/16" (1-5/16" is one size smaller than 1-3/8") (1-3/8" is one size bigger than 1-5/16") (Equal to 34 mm in Metric)
- 1-3/8" (1-3/8" is one size smaller than 1-7/16") (1-7/16" is one size bigger than 1-3/8") (Equal to 35 mm in Metric)
- 1-7/16" (1-7/16" is one size smaller than 1-1/2") (1-1/2" is one size bigger than 1-7/16") (Equal to 37 mm in Metric)
- 1-1/2" (1-1/2" is one size smaller than 1-9/16") (1-9/16" is one size bigger than 1-1/2") (Equal to 39 mm in Metric)
- 1-9/16" (1-9/16" is one size smaller than 1-5/8") (1-5/8" is one size bigger than 1-9/16") (Equal to 40 mm in Metric)
- 1-5/8" (1-5/8" is one size smaller than 1-11/16") (1-11/16" is one size bigger than 1-5/8") (Equal to 42 mm in Metric)
- 1-11/16" (1-11/16" is one size smaller than 1-3/4") (1-3/4" is one size bigger than 1-11/16") (Equal to 43 mm in Metric)
- 1-3/4" (1-3/4" is one size smaller than 1-13/16") (1-13/16" is one size bigger than 1-3/4") (Equal to 45 mm in Metric)
- 1-13/16" (1-13/16" is one size smaller than 1-7/8") (1-7/8" is one size bigger than 1-13/16") (Equal to 47 mm in Metric)
- 1-7/8" (1-7/8" is one size smaller than 1-15/16") (1-15/16" is one size bigger than 1-7/8") (Equal to 48 mm in Metric)
- 1-15/16" (1-15/16" is one size smaller than 2") (2" is one size bigger than 1-15/16") (Equal to 50 mm in Metric)
- 2" (2" is the largest SAE wrench size) (Equal to 51 mm in Metric)

## Standard Wrench Sizes Chart

Here are the most common standard wrench sizes in order, along with one size smaller, larger, and their metric conversion.

SAE Size | One Size Smaller Than | One Size Bigger Than | Metric Equivalent |
---|---|---|---|

1/4" | 5/16" | --- | 7 mm |

5/16" | 3/8" | 1/4" | 8 mm |

3/8" | 7/16" | 5/16" | 10 mm |

7/16" | 1/2" | 3/8" | 12 mm |

1/2" | 9/16" | 7/16" | 13 mm |

9/16" | 5/8" | 1/2" | 15 mm |

5/8" | 11/16" | 9/16" | 16 mm |

11/16" | 3/4" | 5/8" | 18 mm |

3/4" | 13/16" | 11/16" | 20 mm |

13/16" | 7/8" | 3/4" | 21 mm |

7/8" | 15/16" | 13/16" | 23 mm |

15/16" | 1" | 7/8" | 24 mm |

1" | 1-1/16" | 15/16" | 26 mm |

1-1/16" | 1-1/8" | 1" | 27 mm |

1-1/8" | 1-1/4" | 1-1/16" | 29 mm |

1-1/4" | 1-5/16" | 1-1/8" | 32 mm |

1-5/16" | 1-3/8" | 1-1/4" | 34 mm |

1-3/8" | 1-7/16" | 1-5/16" | 35 mm |

1-7/16" | 1-1/2" | 1-3/8" | 37 mm |

1-1/2" | 1-9/16" | 1-7/16" | 39 mm |

1-9/16" | 1-5/8" | 1-1/2" | 40 mm |

1-5/8" | 1-11/16" | 1-9/16" | 42 mm |

1-11/16" | 1-3/4" | 1-5/8" | 43 mm |

1-3/4" | 1-13/16" | 1-11/16" | 45 mm |

1-13/16" | 1-7/8" | 1-3/4" | 47 mm |

1-7/8" | 1-15/16" | 1-13/16" | 48 mm |

1-15/16" | 2" | 1-7/8" | 50 mm |

2" | --- | 1-15/16" | 51 mm |