From bridges and skyscrapers to tunnels and power plants, we rely on the strength and durability of concrete. Understanding concrete PSI (Pounds per Square Inch) is critical for choosing the right mix for each project. But with so many types of concrete available, how do you know which one to use? The answer lies in the concrete PSI chart.
This comprehensive guide will show you how to read and use a concrete PSI chart, explain the difference between nominal and design mixes, and help you assess compressive strength accurately. We’ll also show you where to get the best equipment for all your testing needs in 2025.
What Is a Concrete PSI Chart and Why Does It Matter
A concrete PSI chart is a table that displays the pressure resistance (compressive strength) of various concrete grades. PSI (pounds per square inch) helps identify how much load a concrete mix can withstand before failure.
The PSI rating is crucial for:
- Selecting the correct concrete strength
- Matching the right mix ratio to your project
- Ensuring long-term structural safety
Concrete PSI Chart Table (M5 to M70)
To begin understanding the concrete PSI chart, let’s first examine an example of a standard concrete PSI chart.
|
Concrete Grade |
Concrete Mix Ratio (cement: sand : aggregate) |
Compressive strength (MPa (N/mm2)) |
Compressive strength |
|
M5 |
1 : 5: 10 |
5 MPa |
725 psi |
|
M7.5 |
1 : 4 : 8 |
7.5 MPa |
1087 psi |
|
M10 |
1 : 3 : 6 |
10 MPa |
1450 psi |
|
M15 |
1 : 2 : 4 |
15 MPa |
2175 psi |
|
M20 |
1: 1.5 : 3 |
20 MPa |
2900 psi |
|
M25 |
1 : 1 : 2 |
25 MPa |
3625 psi |
|
M30 |
Design Mix |
30 MPa |
4350 psi |
|
M35 |
Design Mix |
35 MPa |
5075 psi |
|
M40 |
Design Mix |
40 MPa |
5800 psi |
|
M45 |
Design Mix |
45 MPa |
6525 psi |
|
M50 |
Design Mix |
50 MPa |
7250 psi |
|
M55 |
Design Mix |
55 MPa |
7975 psi |
|
M60 |
Design Mix |
60 MPa |
8700 psi |
|
M65 |
Design Mix |
65 MPa |
9425 psi |
|
M70 |
Design Mix |
70 MPa |
10150 psi |
This PSI chart shows concrete strength in both MPa and PSI. U.S. projects typically use PSI, while international ones often rely on MPa. One MPa equals approximately 145 PSI.
Concrete Grades & Correct Mix Ratios Explained
Concrete grades are labeled with the letter “M”, which stands for “Mix”, followed by a number. This number indicates the compressive strength of the concrete in megapascals (MPa) after 28 days of curing. For example, M20 concrete has a strength of 20 MPa. Common grades like M10, M15, M20, and M25 are widely used in residential and commercial projects, depending on structural needs.
Both MPa and PSI measure the same thing: how much pressure the concrete can handle before it fails. MPa is the metric unit (used globally), while PSI is the imperial equivalent (mainly used in the United States).
Next to each grade, you’ll find the concrete mix ratio. This ratio shows the correct parts of cement : sand : aggregate needed to make that grade. For example, M5 has a ratio of 1:5:10, meaning you mix 1 part cement, 5 parts sand, and 10 parts aggregate to achieve a strength of 5 MPa.
Nominal Mix vs. Design Mix: What’s the Difference?
When exploring a concrete PSI chart, you may notice that some concrete grades come with fixed mix ratios, while others are marked as design mix. Understanding the difference between these two types is crucial for choosing the right concrete for your project.
What is a Nominal Mix? (M5–M25)
Nominal mixes are standard concrete grades from M5 to M25, each defined by a fixed ratio of cement : sand : aggregate. For example:
- M10 has a ratio of 1:3:6
- M20 uses a ratio of 1:1.5:3
These mixes are simple, based on years of practical experience rather than lab testing. They’re easy to prepare and ideal for:
- Small to medium construction work
- General concrete repairs
- Non-critical structures like footpaths, patios, and floors
Key Advantage: Anyone can mix nominal concrete by following the ratio.
However, nominal mixes don’t account for:
- Variations in material quality
- Moisture content in sand or aggregates
- Climate conditions or curing time
This can lead to inconsistencies in strength. That’s why nominal mixes are mainly used for non-structural work.
What is a Design Mix? (M30–M70)
Design mixes apply to concrete grades M30 and above. Unlike nominal mixes, they are custom-engineered for each project. A qualified engineer calculates the exact mix based on:
- Target compressive strength (PSI/MPa)
- Material properties (cement type, aggregate size, moisture)
- Water-cement ratio
- Workability and durability needs
- Environmental factors
Design mixes may also include admixtures like superplasticizers, retarders, or waterproofing agents to improve performance.
How It Works: Engineers run lab tests and adjust the proportions through trial batches until the concrete meets the required strength and workability.
Design mixes are essential for:
- Structural elements like beams, columns, and slabs
- Commercial and industrial buildings
- Bridges, dams, high-rise projects
Note: Using a nominal mix for critical load-bearing structures can lead to unsafe or unstable results.
Water-Cement Ratio and Its Importance
The water-cement ratio directly impacts strength, durability, and workability.
A design mix considers the water ratio in cement paste, the unique properties of the materials, and other external factors. Design mixes may also incorporate various admixtures that impact the concrete’s PSI.
When developing a design mix, an engineer will create several batches, experimenting with different ratios to create a concrete mix with the desired PSI strength on the concrete PSI chart.
Experimentation is vital for stronger concrete mixtures because a structural engineer cannot rely on an inconsistent nominal mix ratio when constructing an important structure.
What PSI Strength Do You Need? Real-World Applications
| PSI Range | Common Use Cases |
| Under 3,000 PSI | Sidewalks, flooring, temporary structures |
| 3,000–4,000 PSI | Slabs, foundations, driveways, patios |
| 4,000–6,000 PSI | Columns, beams, parking garages, heavy slabs |
| Above 7,000 PSI | High-rises, tunnels, powerplants, industrial use |
More Read: Concrete Break Machine Models for Efficient Strength Testing.
How to Measure Compressive Strength with PSI Tests
- Sample Prep: Pour fresh concrete into cube or cylinder mold
- Curing: Let the sample cure in a moist environment for 28 days
- Testing: Use a compressometer or automatic concrete compression machine
- Calculation: Divide force by the cross-sectional area (e.g., 10,000 lbs ÷ 4 in² = 2,500 PSI)
What Projects are Different Concrete Mix Ratios Useful For?
We now know that concrete with a higher PSI is more compression-resistant and a Concrete PSI Chart, but how does this apply in the real world?
Nominal concrete mixtures under 3,000 PSI shouldn’t be used for complex load-bearing structures. They are best suited to applications such as:
- Flooring, sidewalks, and driveways
- Repair work
- Temporary structures
Concrete in the range of 3,000-4,000 PSI is well-suited to basic structural components like:
- Columns, beams, slabs, and footers
- Small-scale construction projects
- Slab foundations and footings, especially in situations where heavy loads are expected to be stored or moved, such as RV pads
Design mixtures in the range of 4,000-6,000 on the concrete PSI chart are very strong. As such, an engineer may use them when building:
- Bridges and large-scale buildings
- Warehouses and factories
Higher than 7,000 PSI Concrete
Anything higher than 7,000 PSI concrete is considered ultra-high-strength concrete. These concrete mixtures are used in large-scale load-bearing structures or in situations where contamination is possible. For example:
- Nuclear powerplants
- High-rise buildings
- Bridges and tunnels
How to Test the Compressive Strength of a Concrete Mixture?
Depending on the concrete standards you follow, you may choose to test compressive strength using either a concrete cube or concrete cylinder. Here’s a basic step-by-step guide to testing concrete psi chart and compressive strength.
- Prepare the sample: Take a concrete sample from freshly-poured concrete. Pour the sample into your cube or cylinder mold. Use a tamper to remove excess air and compact the concrete.
- Cure the sample: Remove your concrete from the mold after 24 to 48 hours and cure it according to your chosen standard. This typically involves placing the concrete into a moist environment at a specified temperature for a predetermined period (usually 28 days).
- Test the sample: Place the sample in a concrete compressor such as a compressometer or automatic compression testing machine. These machines apply load at a constant rate following recognized standards.
- Find the PSI: Once the sample fails, calculate PSI by dividing the force applied by the cross-sectional area of the specimen. For example, a 2″ concrete cube has a cross-sectional area of 4 square inches. Let’s assume that the concrete withstood a force of 10,0000 pounds. Dividing 10000 by 4 gives us a concrete strength of 2500 PSI.
Where Can I Find the Best Material Testing Equipment?
Knowing how to interpret a concrete PSI chart is one thing. Having the right equipment for your own concrete testing is another. Certified MTP is your one-stop shop for all your material testing needs.
We offer a range of compression testing equipment, molds, tampers, finishing trowels, and more, designed to make creating accurate concrete mixtures fast, easy and reliable.
Looking for something different? We also offer a range of soil testing, aggregate testing, asphalt testing, and cement testing equipment. Whatever your material testing needs, Certified MTP has the equipment and expertise to help you get things done.
Can’t find what you’re looking for? Get in touch. With thousands of products from some of the world’s leading material testing brands, we’re sure to have what you need.
For more concrete testing needs, consider the popular Mini-Jaw Crusher
Final Takeaway: Why PSI Charts Matter in Construction
Understanding and using the concrete PSI chart helps ensure that every mix meets safety standards and structural requirements. With this guide, you’ve learned:
- How to read and apply a PSI chart
- When to use nominal vs. design mix
- How water ratio affects strength
- Which concrete grade is best for your project
Visit Certified MTP to explore equipment and tools that support strong, safe, and consistent concrete results.
FAQs: Concrete PSI Chart & Strength Testing
What does PSI mean in concrete?
PSI measures how much pressure concrete can handle before failing. The higher the PSI, the stronger the concrete.
What PSI is good for a driveway?
A PSI range of 3,000–4,000 is ideal for driveways, patios, and residential slabs.
What is 7000 PSI concrete used for?
It’s used in high-load projects like bridges, nuclear plants, tunnels, and tall buildings.
Is 5000 PSI concrete stronger than 3000 PSI?
Yes. 5000 PSI concrete has more compressive strength and is more durable than 3000 PSI concrete.
Can I use M25 concrete for slabs?
Yes. M25 (3625 PSI) is a good choice for structural slabs, beams, and residential construction.
How does a concrete PSI chart help in real projects?
It helps select the right mix ratio and ensures safety in structural design.
