Wrench Conversion Chart (Metric / Standard)

A wrench conversion chart is a valuable reference tool for anyone working with both Standard (SAE) and Metric measurement systems.

This chart provides a convenient reference for converting wrench sizes between Metric and Standard for various bolts.

If you don't know the size of the bolt you are working on, you may want to use a bolt sizes chart  first.

Metric To Standard Wrench Conversion Chart

Wrench Size Conversion Chart

You can Download This Wrench Conversion Chart.

Bolt Size Metric Standard (SAE)
1/8″ 8 mm 5/16″
3/16″ 10 mm 3/8″
1/4″ 11 mm 7/16″
5/16″ 13 mm 1/2″
3/8″ 14 mm 9/16″
7/16″ 16 mm 5/8″
1/2″ 19 mm 3/4″
9/16″ 21 mm 13/16″
  22 mm 7/8″
5/8″ 24 mm 15/16″
  25 mm 1″
3/4″ 29 mm 1-1/8″
  32 mm 1-1/4″
7/8″ 34 mm 1-5/16″
  35 mm 1-3/8″
1″ 38 mm 1-1/2″
  41 mm 1-5/8″
1-1/8″ 43 mm 1-11/16″
  45 mm 1-3/4″
1-1/4″ 48 mm 1-7/8″
1-3/8″ 51 mm 2″
1-1/2″ 57 mm 2-1/4″
1-5/8″ 64 mm 2-1/2″
1-3/4″ 67 mm 2-5/8″
  70 mm 2-3/4″
1-7/8″ 75 mm 2-15/16″
  76 mm 3″
2″ 80 mm 3-1/8″
  83 mm 3-1/4″
2-1/4″ 89 mm 3-1/2″
  95 mm 3-3/4″
2-1/2″ 99 mm 3-7/8″
  102 mm 4″
2-3/4″ 108 mm 4-1/4″
  114 mm 4-1/2″
3″ 118 mm 4-5/8″

How to Use

First, determine the metric size of the bolt or nut that you are working with. This can be measured with a metric ruler or caliper.

Next, locate the corresponding metric size on the left-hand side of the chart. This will typically be listed in millimeters (mm).

Once you have located the metric size, follow the row across the chart to find the corresponding standard size on the right-hand side of the chart.

These different measurements refer to two different systems of measurement: SAE (Society of Automotive Engineers) and metric. SAE measurements are based on inches, while metric measurements are based on millimeters.

For exact measurements use the MM to Inch chart.

About This Wrench Conversion Chart

The chart is simply a guideline and the actual size of the wrench/spanner needed may vary depending on factors such as the manufacturer of the bolt or nut, the type of material being used, and how worn the bolt/wrench is.

As always, exercise caution and use the correct tool for the job to avoid damage or injury.

For more information on socket set sizes visit the socket set charts


  • The article presents a "Standard to Metric Wrench Conversion Chart" for those working with imperial (standard) and metric measurement systems.
  • This chart aids in converting wrench sizes between the two measurement systems for efficient work.
  • The chart provides corresponding metric and standard (SAE) wrench sizes for various bolt sizes.
  • To use the chart, determine the metric size of the bolt, find the corresponding metric size on the left, and then identify the corresponding standard size on the right.
  • The chart is a guideline; actual wrench sizes may vary due to factors like manufacturer, material, and wear.
  • Caution and the correct tool usage are emphasized to prevent damage or injury.