What types and sizes of pavers are there, and which do I need?

The three main paver types

Type	What it is	Standard	Best fit
Concrete pavers	Factory-made units of cement, aggregate and usually pigment, made from a very low-water mix[2]	ASTM C936 in the US[1][3]	Patios, walks, driveways, pool decks; widest range of shapes and colors
Clay brick pavers	Clay or shale fired at high temperature[4]	ASTM C902 for pedestrian and light traffic[4]; ASTM C1272 for heavy traffic[5]	Classic brick look; color is fired in, not pigmented
Natural stone	Quarried stone such as sandstone, bluestone, limestone, granite or slate	Material standards by stone type, such as ASTM C616 for quartz-based stone[6]	Flagstone and cut-stone patios and walks

Concrete pavers: what ASTM C936 requires

ASTM C936 is the US specification for solid concrete interlocking paving units, and the current edition is C936/C936M-24^[3]. CMHA, the trade group that absorbed the Interlocking Concrete Pavement Institute (ICPI), summarizes its main requirements^[1]:

• Average compressive strength of at least 8,000 psi (55 MPa).
• Average absorption no greater than 5%.
• Length and width within plus or minus 1/16 inch; height within plus or minus 1/8 inch.
• Freeze-thaw testing under ASTM C1645: average mass loss no more than 225 g/m² after 28 cycles, or 500 g/m² after 49 cycles. Pavers that will see deicers are tested in a 3% salt solution.

ICPI's application guide adds the shape limits. A concrete paver under C936 has a surface area of no more than 101 square inches and a length-to-thickness (aspect) ratio no greater than 4, with a minimum thickness of 2 3/8 inches^[2]. Larger, thinner units are slabs or large-format pavers, which behave differently. See large-format pavers.

What to ask: whether the product is tested to ASTM C936. ICPI says US-made pavers from its member producers typically meet it^[2].

Concrete paver thickness: 2 3/8 vs 3 1/8 inches

Use	Recommended thickness (ICPI)[2]
Patios, walks, pool decks, residential driveways	2 3/8 in (60 mm)
Pavements with regular vehicle traffic	3 1/8 in (80 mm)
Heavy-duty commercial	4 in (100 mm), sometimes more

ICPI adds an aspect-ratio rule for anything a car will touch. Units with an aspect ratio of 4:1 or more should not be used under vehicles. Units between 4:1 and 3:1 can work where car use is limited, such as a residential driveway. Units at 3:1 or less suit all vehicle areas^[2]. For areas under steady traffic, ICPI recommends 45 or 90 degree herringbone patterns for the most interlock^[2].

A common upsell is "you need the thick paver for a driveway." For a typical home driveway, ICPI's guidance says 2 3/8 inches is enough when the base is built right^[2]. The base, not the paver, carries most of the load. See paver base and installation basics.

Clay brick pavers: classes, types and sizes

ASTM C902 covers clay brick for pedestrian and light traffic, including residential driveways. It is not meant for heavy vehicle traffic^[4]. The Brick Industry Association (BIA) explains how a C902 paver is graded^[5]:

Grade	Options	What to pick for an outdoor home patio
Class (weather)	SX: may freeze while wet. MX: exterior, no freezing. NX: interior only	SX for most exterior residential use[5]
Type (abrasion)	I: extensive abrasion. II: intermediate traffic, including residential driveways. III: low traffic, such as single-family patios	I or II for most exterior residential use[5]
Application (look and tolerance)	PS: general use. PX: tight tolerances for narrow joints. PA: deliberate variation in size, color or texture	PS or PX for sand-set; PA for an antique look[5]

Sizes. BIA lists 4 by 8 inches and 3 5/8 by 7 5/8 inches as two commonly specified sizes. The smaller one is sized so a mortar joint brings it to an 8 inch module^[5].

Thickness. C902 sets no minimum thickness, but clay pavers are commonly made 2 1/4 inches and 1 1/2 inches thick. BIA says the 1 1/2 inch units usually go over a rigid (concrete) base, except for patios or walks at one- or two-family homes in warm climates with limited frost^[5].

Natural stone pavers

Stone is graded by the standard for its rock type, not by a paver standard. The Natural Stone Institute's design manual lists them: granite ASTM C615, limestone ASTM C568, marble ASTM C503, quartz-based stone (sandstone, bluestone types, quartzite) ASTM C616, and slate ASTM C629^[6].

The same manual suggests a minimum thickness of 1 1/4 inches for exterior stone pavers under foot traffic. For vehicle traffic it says thickness is best set by engineering analysis and is generally 3 inches or more^[6]. It also recommends exterior joints of at least 1/4 inch, preferably 3/8 inch, and 1/2 to 1 inch for stones with split edges^[6]. Irregular flagstone gets its own page: flagstone patios and walkways.

Common sizes and how many you need

Paver face size	Pieces per 100 sq ft (HomeGuide)[7]
4 x 8 in	450
6 x 6 in	400
6 x 9 in	267
8 x 8 in	225
12 x 12 in	100
12 x 18 in	67

Order about 10% extra for cuts and breakage, or 20% for angled patterns^[7]. Many concrete paver lines are sold as mixed-size bundles. Ask for the coverage per pallet instead of counting pieces.

How to choose

• Patio or walk, any climate: 2 3/8 inch concrete pavers, Class SX clay pavers, or stone at least 1 1/4 inches thick all fit the published guidance^[2][5][6].
• Driveway: 2 3/8 inch concrete pavers with a low aspect ratio in herringbone, or Type I or II clay pavers. Avoid long, thin slabs^[2][5].
• Freeze-thaw with deicers: ask for freeze-thaw test results in salt solution for concrete pavers^[1], and Class SX for clay^[5].
• Pool deck: ICPI lists pool decks as a standard concrete paver use^[2]. Pick a textured surface.

When to call a pro

• You want pavers on a driveway, a slope or near a pool, where base and pattern choices matter more.
• You live with hard freezes or deicing salt and need product test data matched to that exposure.
• You are mixing paver sizes or patterns and need a layout that keeps joints tight.
• You want bids from independent installers who can name the exact product and its ASTM standard.