SAE to metric conversion size chart (standard & inch to mm & cm)

With the help of this SAE to metric conversion size chart, you’ll easily convert standard & inch to mm & cm. If you have a socket or wrench, you need to determine what it converts into. The size chart can help you determine the mm to SAE conversion, whether you’re converting from one to the other. Check out the SAE size chart below. It allows you to easily jump between standard, metric, inches & feet!


The SAE to metric conversion size chart below is the easiest way to convert standard & inch measurements to mm & cm. For instance, you can see the following in the chart:

  • 1 1/8 converts to a 28.575 mm socket.
  • 7mm falls in between and converts to a 1/4 or 9/32 standard.
  • 8mm falls in between and converts to a 5/16 or 11/32 standard.
  • 12mm falls in between and converts to a 7/16 or 1/2 standard.
  • 17mm falls in between and converts to a 5/8 or 11/16 standard.

Table of Contents

SAE & Metric Screw Size Chart to convert standard & inch to mm & cm

With SAE & metric screw size chart, you’ll be out doing your various projects in no time. Make sure you get the right socket size and wrench! This wrench conversion chart helps you find out the differences. You can easily look up the fractions for socket wrenches to find their diameter and equivalents.

Standard (SAE)Metric (mm)Metric (cm)InchFeet
1 1/1626.98752.698751.06250.089
1 1/828.5752.85751.1250.094
1 3/1630.16253.016251.18750.099
1 1/431.753.1751.250.104
1 5/1633.33753.333751.31250.109
1 3/834.9253.49251.3750.115
1 7/1636.51253.651251.43750.12
1 1/238.13.811.50.125
1 9/1639.68753.968751.56250.13
1 5/841.2754.12751.6250.135
1 11/1642.86254.286251.68750.141
1 3/444.454.4451.750.146
1 7/847.6254.76251.8750.156
2 1/853.9755.39752.1250.177
2 1/457.155.7152.250.187
2 3/860.3256.03252.3750.198
2 1/2es63.56.352.50.208
2 5/866.6756.66752.6250.219
2 11/1668.26256.826252.68750.224
2 3/469.856.9852.750.229
2 7/873.0257.30252.8750.24
3 1/879.3757.93753.1250.26
3 1/288.98.893.50.292
3 3/495.259.5253.750.312
5 1/2139.713.975.50.458

Standard to metric conversion should hopefully be a breeze with the metric conversion table above!

With the dynamic society, we must have basic knowledge of the units of measurements used today, either SAE or metric. We are primarily conversant with only the system used in our home countries.

Conversion from SAE to the metric system is a tiring and grueling experience. Conversion charts are tables designed to help you easily switch from one to another without making any errors. Many people often complain that the charts in circulation are challenging to use; we decided to create and design one that you can quickly utilize.


Do I need a table? This is a question that we often ask. We fail to realize that different items come in various measuring systems. The king-sized bed you use could be sold in inches while bedding is in centimeters; thus, having basic knowledge of the sizes will help you choose the right sized items. Placing your orders in online businesses requires prior knowledge of the goods needed to avoid costs incurred on returning.

Choosing the appropriate wrench size for basic repairs will also test your knowledge of the units. Their sizes could be written in millimeters, while nuts and bolts are inches. Our table will quickly help you navigate through such experiences.

SAE hex set

Have you ever traveled to a foreign country and found measuring volume units different from what you are used to? Maybe water sold in ounces or petrol in gallons? To refill enough gas for your car, conversion to volume units you are familiar with is vital. The evening news bulletin giving the price of crude oil in barrels. At the same time, we only understand liters necessitates a relevant chart.

It is advisable to have your work done to perfection. A task as easy as buying an electric cord for your house could leave you homeless! The reason for this being if you get the wrong one, it could lead to a fire that will burn down your house. Nonetheless, you can view an electrical cord guide here.

We have listed the SAE equivalents in millimeters and centimeters for your convenience. You’ll also find it in inches and even feet! Let’s take a closer look at all of these in detail.

Best devices to measure SAE & metric

Consider one of these gifts for yourself. There’s an easy standard-to-metric chart magnet to put on your fridge! This impact socket set makes switching between different sizes or the easy thread identifier.

Magnet chart
Thread Detective
Universal socket set
Magnet America Standard to Metric Conversion Chart Magnet is 3 1/2" x 10 3/4" Made for Vehicles and Refrigerators
Thread Detective / Thread Identifier Mini Metric and SAE / Inch Set
CASOMAN 3/8" Drive Impact Socket Set, 48 Piece Standard SAE and Metric Sizes (5/16-Inch to 3/4-Inch and 8-22 mm), 6 Point, Cr-V Steel Socket Set
What we love
Great, cheap magnet to put on a fridge.
Easy tool to identify the right thread.
Great socket set to upgrade your tool set.
Magnet chart
Magnet America Standard to Metric Conversion Chart Magnet is 3 1/2" x 10 3/4" Made for Vehicles and Refrigerators
What we love
Great, cheap magnet to put on a fridge.
Thread Detective
Thread Detective / Thread Identifier Mini Metric and SAE / Inch Set
What we love
Easy tool to identify the right thread.
Universal socket set
CASOMAN 3/8" Drive Impact Socket Set, 48 Piece Standard SAE and Metric Sizes (5/16-Inch to 3/4-Inch and 8-22 mm), 6 Point, Cr-V Steel Socket Set
What we love
Great socket set to upgrade your tool set.

Thread Detective

When you need to figure out the right metric or SAE size, the thread detective can help you out. Here’s some more information on it.

NameThread Detective
Item Weight‎5.8 ounces
Product Dimensions‎5 x 1.2 x 8.5 inches


  • It’s very easy to use.
  • Find the right thread in less than 30 seconds.
  • Laser-etched numbers indicating sizing


  • We wish the female testers would spin as it would make them easier to use.
  • It’s a premium set that’s a bit more expensive than alternatives.
Here's a great thread detective.

Standard to metric sticker conversion chart

Here’s a great magnet to put on the fridge.

BrandMagnet America
ForFridges & metal surfaces
Item Weight0.493 ounces
Made inNC
Package Dimensions10.5 x 3.6 x 0.01 inches


  • It’s cheap.
  • It’s easy to use.
  • It can be placed on a bunch of surfaces in the garage.


  • You won’t have to come back to this website when you get the magnet.
  • Your wife may not want this magnet on the fridge.
  • It doesn’t have the depth that the chart on this page have.
Put it on the fridge.

What is SAE, Or Standard?

tool chest

SAE stands for Society of Automotive Engineers and is now known as SAE International. It’s the organization that standardized the units for ease of usage. The organization has a membership of over 128,000 worldwide. It’s responsible for advancing and setting standards in the engineering space. SAE has set standards for measurement that are not only followed by most of North America’s construction and automotive industry. They have also made the engineering and production aspect a piece of cake.

Units of measurement are a medium of communication. The standard size lengths were needed to enhance accuracy. The Roman Empire initially developed the system where one foot was generally the length of a human being. An inch was the width of a thumb, on the other hand.

SAE International took these basic units one step further and developed the evolved SAE measurement system. It continues to spread other technical information and set North American standards in the construction and auto industry. It does so through forums, magazines, journals, and periodicals.

wrench set

It is mainly used in the UD and formerly in the UK. In the UK, it is referred to as the Imperial system. Other countries adopted another method of measurement, metric. Thereby, they left the two countries as the system’s primary users. Units of division in this system are in eighths and twelfths. With these scale graduations, it becomes tough to read the scale.

SAE units are also granted the label of UD Customary Units (USCS). It indicates the official unit used in the USA is not the same as the Metric system. It is also incompatible with the British Imperial system. It is a common mistake to use the Imperial system and SAE interchangeably as they are different systems.

They were used during the USA’s Industrial Revolution, thus cementing their use. The manufacturing and construction industry adapted its use as the accepted standard. You can use our metric-to-standard conversion tables to get the units you need for your project.

Pros of SAE system / Imperial units

  • Often easier to use fractions as this system employs
  • Great for daily use
  • Easier to understand than the metric system.
  • The names are easier to remember than confusing prefixes like liter and meter.


  • Conversions are more difficult than the metric system.

Now let us take a closer look at the metric system used in other parts of Europe and some parts of Asia and Africa.

Time needed: 5 minutes.

In any given place of your living, there’ll be a standard system of measurement that’s being followed. When you come into contact with other locations and their standard measurement systems, confusion begins. Follow the steps below to convert easily from one system to another to make this easier.

How do you convert between standard and metric units?

  1. Verse yourself in the equivalents.

    You will have to be fluent in the equivalent values of the metric and standard units. You’re going to want to know how many kilometers in a mile and how many centimeters in an inch.

  2. Set up the equation

    When familiar with the equivalents, you can easily set up an equation to solve and quickly find out the resulting answer.

    If there are 2.54 cms in 1 inch, how many centimeters in 3.5 inches?

    Here’s how the equation will be set up:

    Inches: centimeters = Centimeters: inches

    1 inch : 2.54 cms = X cms: 3.5inches
    nuts and bolts next to a ruler

  3. Solve the equation

    You can solve the equation by multiplying the inches by the centimeter value on the left.

    X= 3.5 x 2.54
    X= 8.89 cms

    And voila! You have successfully converted from one unit to the other.

Now you know how to do metric to SAE conversions.

What is the Metric System?

It is a measurement system developed in the 18th century after the French Revolution. It is a measurement system with meter, liter, and gram as the standard. It’s used for length, volume, and mass. You will most certainly realize this model of representing lengths is the most common globally.

Units of measurements are subdivided into tenths, making the reading of this scale much easier than the other systems. The most common engineering level of the scale is the millimeter (mm). It is easier to read. Being the smallest, it can represent any length.

What makes the system most resourceful is the ability to be intuitive and interconnected. For instance, 1 liter of water will weigh 1 kg.

Thanks to its convenient measurement method and Napoleon’s triumphs, this system spread far and wide. Great Britain also accepted some metric units over the British Imperial system. The older generations in Britain may still use the older Imperial method. The youngsters prefer their kilograms and millimeters.

Pros of the Metric System

  • Using prefixes like meter and kilo makes the conversion and comprehension process simpler.
  • Metric units can be as precise as you need them to be. For instance, you can use mg instead of grams when the item is smaller.
  • This system has simplicity due to fewer number of units to reduce confusion.


  • Due to fewer units, it can be difficult to apply in many places. For instance, cooking often turns to teaspoons and tablespoons because grams are too small and kilograms are too huge of a unit.

What are millimeters and centimeters used for?

Both Millimeters(mm) and centimeters(cm) are part of the metric system. While mm is a unit of length, cm can be used for both length and area. One mm is 0.1cm and one cm is 10mm. Since mm is the smaller unit, it denotes the very small but visible lengths and distances. For instance, the thickness of a wire or the length of your nail.

On the other hand, a centimeter is a larger unit and is roughly the 100th part of a meter. It can be used to measure the size of medium-range objects. It’s great for the distance between two points in the vicinity. Where larger distances are involved, the meter is chosen over the centimeter.

SAE (Standard) vs. METRIC UNITS

Here’s what you need to know when it comes to the whole debate of SAE (standard) vs. metric.

SAE was incorporated into the whole automotive industry, although it took time. In the beginning, the standard was only used for vehicles. However, they are currently utilized in all modes of transport. Airplanes and boats adapted the system to become the preferred means of measurement. It happened when SAE changed from Society of Automobile Engineers to Society of Automotive Engineers.

The metric system is more prevalent in other countries. Major vehicle manufacturing hubs such as Japan and Germany use this mode. We now have vehicles with nuts and bolts in the metric system, which led to SAE sizes and metric-sized wrenches development.

It means if you’re an engineer looking to work on foreign cars made by companies like Nissan or Kia, you’re going to be buying metric equipment. But if you’re only looking at the domestic market, then you’re good to go with SAE sockets.

Nowadays, another innovation is also becoming more and more popular. Due to rising production costs in the USA, their big vehicle manufacturing companies source parts in other countries. The trend has led to vehicles having different components with different measuring systems. You can find the engine and its members in the metric system while the rest of the car is in SAE. It has given rise to the need for universal wrenches.

Repairs now require high-precision tools such as plasma glass cutters which accurately cut whatever component you need. MIG welders are also used for simple welding jobs. With vehicles now considered expensive investments, choosing the perfect wires for repairs requires an expert opinion.

Metric vs. Imperial System

For imperial vs. metric, take a look at this section to understand the two better.

tape measurer

An Imperial system is a form of older standardizations that have given way to more logical and thoughtful designs. It was mainly used in the UK. One foot was subdivided into twelve units or inches. Formerly it was equal to 11.6 inches. We can now quickly and comfortably represent inches as a foot or vice versa. The monarch made all these changes in ancient times, hence the Imperial.

The UK transitioned over later on, however. It was necessitated by the need to have a standard unit globally. After the French Revolution, the French developed the metric system. Napoleon’s conquests led to its acceptance in other lands.

It is the current base International System of Units (SI) for length. If you use or understand both the metric and imperial system, you will find the former easier to use.

screwdriver on a white background

SI Units

These universal units of measurements were agreed on to reduce confusion with data representation. With these, scientists can easily discuss their findings globally. An engineer can design a car in Germany and send the design to China, where it will be manufactured to the exact length.

Preparing various tools of different sizes for motor vehicles needs high-quality lathe machines. We have prepared a list of high-precision and easy-to-use lathe machines. They will give you the best quality for your money with medium-sized lathes which can fit in your garage.

SAE wrench set


What is the inch used for?

An inch is also a unit used commonly in the USCS and the imperial units. Throughout history, its denotation has been shifting and adapting to modern times. It originally meant one-twelfth of a Roman foot. During the reign of King David I of Scotland, an inch went on to mean the size equal to the breadth of a man’s thumb. Under the monarchy of King Edward II in the 14th century, the inch represented the size equal to three grains of dry barley. It was placed lengthwise next to each other.

Don’t worry. Today you won’t need barely to do the math. An inch officially means 2.54cm as of 1959.

What is the foot used for?

The origin of this one shouldn’t be too hard to guess. Human body parts were popular tools for measurement all around the world. The foot was popular in Rome and China, while other places used the cubit for units of length and area. While the standard Roman foot was 295.7mm, the Greek foot was around 302mm. This measurement changed again after the fall of these empires.

In England, archeologists identified the use of this unit dating back to the construction of the Stone Henge in the form of the Neolithic foot.

Due to its controversial nature, it was not surprising that an international conference had to meet and standardize its value.

In imperial units, a standard foot denotes the value of 1/3 yard. Since 1959’s International Yard and pound agreement, the yard has been standardized to 0.9144 meters. This meant the international standard for the foot was then simultaneously set at 0.3048 meters. It is widely used for measuring lengths and distances between points to date.

What are Acres?

Have you tried to buy land sold in acres and didn’t know the extent of the size? Real estate is a long-term investment that requires prior knowledge due to the enormous amounts of money involved.

Purchasing the land without having a mental image could lead you to buy land smaller or larger than you need. Letting of apartments and office spaces has now been converted to square units. Getting a good value for your money will only happen when you know how big it is. We will help you change to the units that you entirely relate to.

Acres are a measurement of land and are part of both the USCS and the Imperial systems. It was designed in the Middles Ages as the area to ideally be plowed by one ox and one man in a single day.

Today, it stands for various measurements in different countries. In the USCS, one acre is roughly 4840 square yards. In SI, it is 4046.9 square meters. An acre refers to 1/640 parts of a square mile in the Imperial system.

Fun fact and note of caution: Sometimes, the Puerto Rican Cuerda is called the Spanish Acre. It is equivalent to 0.96 acres. Confusing acre and Spanish acre could land you in some trouble, so make sure to keep the two separate!

What is 7mm in standard?

7 mm or 0.7cms reads as 1/4 in standard. This is also true for 6.35mm, 6.5mm, and 7mm.

What size is 7/8 in mm?

This size of 7/8’th of an inch converts to 22mm. This can also be read as 0.22cm in metric units.

Conversion at home

When moving to a new office or apartment, you need extension cords to power your appliances. Choosing the right power cables can be a real struggle. You can get advice on how to choose the right extension here. You will get tips on connection and usage from the experts in the link.

It is a landowner’s dream to have well-manicured lawns and property landscaped to their liking. A garden will require a tractor suited for your property size if you have a garden. A tractor is an expensive investment; hence it needs proper guidance before purchase. You should strive to buy a top-rated machine and the best fit for performing tasks when required.

While revamping your home, you will need a basic understanding of the units of measurement. Some materials you will need are sold by the foot. An example is wood. Others are in meters. With this knowledge, you can prepare for the renovations needed regarding how big your furniture should be. If you’re looking to purchase property or buy car parts, knowing your British units from the American ones is good. It will give you the upper hand even before browsing.

Easy and simplified conversion size chart


It would be best to have a domestic wrench toolbox to help renovate. The sizes and types of wrench needed to depend on the bolts and fasteners you have. It is not unusual to find the fasteners and wrenches in different units of measurement. However, you will discover equivalent lengths in various sizes with our chart.

We aim at helping you with arithmetic computations and save your time by providing an accessible and simplified table. Our tables can be easily used by elementary school kids if needed.

Making a few vehicle repairs from home will lead to the need for a simplified chart. Tools used such as wheel spanners or nuts for tire tightening could be in either unit. A conversion table makes it easier to perform the tasks without a mechanic, making it cheaper to maintain your car.

nut driver set

We hope this article helped you learn about the various standards around the globe. Your next trip to Home Depot doesn’t leave you scratching your head as a consequence. Hopefully, SAE to metric conversion and a metric to standard conversion has gotten easier!

Make sure to also check out our guide on adding a shower to a half bath & our guide on shower vs. bathtub resale values. Hopefully, this has made finding the right bolt size easier, even without a fancy calculator or formula. Avoid stress and strain, and you won’t need Poisson’s ratio. You can just move up the page. We’ve also covered you with a wrench conversion chart and made it easy to find the right drill bit.

Hopefully, you’re no longer confused by imperial socket sizes. There is no need to dig into velocity, acceleration, & torque if you don’t have to!

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