Concrete MPa Grades Australia: 20 MPa, 25 MPa, 32 MPa, 40 MPa

Expert guidance: Jason Chandler is a recognised leader in high-performance, sustainable cements and concretes, bringing more than 22 years of construction industry experience in technical, operational, project management and innovation roles.

The information in this guide is indicative and gives examples of common uses only. You should always check with an engineer to confirm the appropriate concrete strength for your application.

What Is MPa in Concrete?

MPa stands for megapascals. In concrete, it measures compressive strength after 28 days. N20, N25, N32, and N40 are Australian normal-class grade names for 20, 25, 32, and 40 MPa concrete.

The letter and number answer different questions. In N32, the N is the normal-class label and 32 is the characteristic compressive strength: 32 MPa at 28 days. MPa is not a rival to the grade number; the MPa value is built into the grade name.

Higher strength generally provides higher durability where the same materials are used. A mix that is structurally adequate may still need a higher grade because of traffic, moisture, chemical exposure, or other local conditions.

Quick Reference: Australian Concrete Grades

The table below covers every standard grade you'll encounter on a residential or light commercial project in Sydney. Prices are delivered rates for March 2026. see Sydney delivery pricing for a breakdown of delivery fees and surcharges, or check national price guidance.

Source: Australian Standards AS 1379 and Cement Concrete & Aggregates Australia (CCAA).

Not Sure Which Grade? Use the Selector

Quick Answers: Driveway, Slab, Footings, Pool and Paths

If you already know the project type, use this as the starting point before checking engineering drawings or council requirements. The final order still needs the specified grade, slump, volume, and delivery access.

When to Use Each Grade

20 MPa (N20): Paths, Blinding, Light-Duty Slabs

20 MPa (N20) is the entry-level structural grade and the cheapest option at $320–340/m³ in Sydney. It's suitable for garden paths, concrete blinding under footings, and light-duty areas that won't carry vehicle loads.

Don't use 20 MPa where vehicles will drive. Its lower compressive strength gives it greater potential for surface wear and cracking under repeated wheel loads. The saving over higher strength grades is often not worth it for work expected to last 20+ years. See the full N20 concrete guide for suitable jobs, price, and ordering.

25 MPa (N25): Driveways, Residential Slabs, Garage Floors

25 MPa (N25) provides higher performance than 20 MPa concrete, with improved strength and durability.

It can be used for standard driveways, residential house slabs, garage floors, pergola footings, and most flat concrete work carrying passenger vehicles. Some areas require higher strength for durability, including parts of coastal and southwestern Sydney. The N25 concrete guide covers driveway and slab guidance, price, and live availability.

32 MPa (N32): Structural Slabs, Exposed Footings, Pools

32 MPa (N32) is required by AS 3600 for exposed footings and is the most commonly supplied grade for structural slabs in Sydney residential construction. At $370–400/m³, it costs more than 25 MPa and provides improved structural performance.

It can be used for exposed footings, pool surrounds and structural pool walls, retaining walls, and any slab that a structural engineer has specified in writing. When deciding between 25 MPa and 32 MPa, the cost difference is often small enough that the higher strength is worth considering with your engineer. The N32 concrete guide covers structural slab and footing use, exposure classes, and price.

40 MPa (N40): Commercial, Multi-Storey, High-Performance

40 MPa (N40) is a higher-performing grade often used in commercial and multi-storey residential construction and suspended slabs. At $400–440/m³, it's rarely specified for standard residential projects unless a durability requirement exists. The N40 concrete guide covers high-load structural use and price.

S-Class: Special-Class Concrete Outside Normal N-Grades

S-class concrete falls outside the normal N-class definitions. All decorative concretes are S-class, including coloured, exposed, and polished aggregate mixes. Other uses include narrow pump-line mixes, high- and low-slump mixes, bridges, industrial foundations, and structures with specific chemical resistance or load requirements. These mixes are architect- or engineer-specified. Price is on application; expect $350+/m³.

Australian Standards Reference

The two standards that govern concrete grades in Australia are:

• AS 1379: Specification and Supply of Concrete: Defines normal-class (N-grade) concrete. The grade number is the characteristic compressive strength in MPa at 28 days.
• AS 3600: Concrete Structures: Specifies minimum grade requirements for different structural applications. Requires 32 MPa (N32) for exposed footings and most structural elements.

The Building Code of Australia (BCA/NCC) requires a minimum of 20 MPa for residential concrete slabs. Most structural engineers in Sydney specify 25 MPa (N25) or higher for anything beyond blinding and paths for improved long-term durability in the coastal and sub-coastal climate.

When a concrete supplier asks for your "spec", they're asking for the grade, slump (workability, though technically slump is a consistency test), and sometimes the maximum aggregate size. Use the values shown on the engineering specification.

Grade vs Price: Is Upgrading Worth It?

The decision rule is simple: if the driveway has heavy loads, exposure, or engineer risk, choose the higher MPa grade. For most Sydney residential projects under 6m³, the grade upgrade can be worthwhile for improved long-term performance.

Need to calculate exactly how much concrete you need first? Use the MixHub calculator to get volume, grade recommendation, and a Sydney price estimate in one step.