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concreting a bridge slab using a concrete pump during the winder. Rebar.
concreting a bridge slab using a concrete pump during the winder. Rebar.
Rebar Size Guide & Charts: Grades, Types, and Weight Specifications
6 minute read
Kevin Forestell headshot
Kevin Forestell
July 28, 2023

Rebar Size Guide & Charts: Grades, Types, and Weight Specifications

While it's not visible in the final product, rebar plays a part in the majority of concrete projects. Rebar provides reinforced strength to any concrete structure to help them resist forces like stretching, bending, or twisting. All of these forces happen to buildings as a result of environmental factors over time. Using these reinforcing steel bars allows the structure to handle heavier loads and resist deflection.

Increasing the lifespan of structures is the main motivator for using rebar. The way that concrete and rebar work together to reinforce the concrete is crucial to the building's structural integrity and longevity. Rebar comes in a variety of different grades that are represented by the minimum yield strength of the steel. These different types of rebar are used across several building types.

How to Read Rebar Markings

At the very top of the piece of rebar, below the main ribs, there will be a letter or a symbol to indicate the production mill. Below that, there will be a number that will indicate the bar size.

Underneath the bar size, there will be a letter, usually S (carbon steel), A (axle steel), W (low-alloy steel), SS (stainless steel), or CS (low-carbon chromium). These letters resemble the type of reinforced steel.

The last marking you will find is the grade mark. The grading scale is represented by a set number of lines to represent the grading. A rebar size of 60 is represented by one line, 75 by two lines, 80 and 100 by three lines, and 120 by four.

How to Measure Rebar Diameter

To determine your rebar's diameter, you should measure the thickness of the rebar across its circular cross-section. This can either be done by using a caliper or tape measure.

When using a caliper, open the jaws and place the rebar perpendicular to the rebar's axis. From there, slide the caliper's jaws together until they touch on opposite sides of the circular rebar. Then record the measurements shown on the caliper's scale.

When trying to measure larger-diameter rebar, it's recommended that you use a tape measure. Wrapping the tape measure around the rebar, ensuring it forms a circle around the thickest part of the rebar. Note the measurement where the tape measure overlaps.

For example, if you measure 12 millimeters using a caliper or find that it aligns with the 1/2" mark on a tape measure, the rebar is 12 mm or 1/2" in diameter, respectively.

Rebar Size Chart

Below is a rebar size guide that can help you decide what is the most appropriate rebar for your construction needs.

Rebar Size Chart
Imperial Bar SizeWeight per unit length (lb/ft)Mass per unit length (kg/m)Nominal Diameter (in) Nominal Diameter (mm)Nominal Area (in^2)Nominal Area (mm^2)

What are the Rebar Grades?

Learning about rebar grades is necessary and it's also crucial to understand what is being measured. This includes both tensile strength and yield strength. Tensile strength refers to the maximum stress that a material can withstand before it breaks when stretched or pulled. It is measured in pounds per square inch (psi) or megapascals (MPa). Yield strength is the stress at which a material begins to deform, and it is also measured in units of force per unit area, such as psi or MPa.

Rebar comes in multiple grades, with specific grades depending on the standards within that region. The most five common grades are 40, 60, 75, 80, and 100.

Grade 40 rebar has a minimal yield strength of 40,000 pounds. Grade 60 rebar has a minimum yield strength of 60,000 psi or approximately 420 MPa. It is one of the most commonly used rebar grades for general construction purposes.

Grade 75 has a minimum yield strength of 75,000 psi or around 520 MPa, making it optimal for high-stress applications and structures that need higher strength. When a project demands a grade greater than 60 or 75, rebar with a grade of 80 is used. It has around 550 MPa and 80,000 psi as a minimum yield strength.

Grade 10 is the most high-strength rebar with a minimum yield strength of 100,000 psi or around 690 MPa. Overall, the appropriate rebar grade for the project is based on the structural design requirements, load-bearing capacity, and environment.

Types of Rebar

Some rebar types are better suited for specific environments. Mild or black rebar is most frequently used for the majority of general construction purposes. This type of rebar is used because of its strength and durability. Additionally, most general construction projects are not exposing the rebar to high-humidity locations.

Epoxy-coated rebar is most commonly used in corrosive and marine environments. Having an epoxy coating on the rebar helps to provide extra protection against corrosive elements and moisture. Stainless steel rebar is most frequently used in situations where corrosion resistance is the primary concern. Stainless steel rebar provides strength and long-term resistance from chemicals, like road salt and other chemicals.

Rebar comes in various grades, with different yield strengths, and it's available in different types suited for specific building requirements. Using rebar significantly extends the lifespan of structures as it works side by side with concrete to enhance structural integrity, ensuring durability and longevity.

Providing tensile strength, rebar enables structures to resist the stretching, bending, and twisting caused by environmental factors. This reinforcement allows buildings to handle heavier loads and resist deterioration. Understanding the importance of rebar will help you construct more formidable, cost-effective projects.

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Kevin Forestell headshot
Kevin Forestell
Kevin Forestell is CEO of DOZR and one of the co-founders. Kevin first got started as an entrepreneur when he founded Forestell Landscaping right after graduating from University. His love and passion for the industry and desire to help solve an equipment problem that contractors faced every day is what brought the founding team to start DOZR. Kevin is proud of the level of efficiency brought to the industry through DOZR and hopes that DOZR will help change the standard way equipment is rented.
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