8×8×16 Cinder Block Coverage, Courses, and Mortar Reference

May 31, 2026

Standard 8×8×16 Cinder Block Dimensions

The 8×8×16 is the most common cinder block size used in residential and light commercial construction. “8×8×16” refers to nominal dimensions — the actual block measures 7⅝×7⅝×15⅝ inches. The difference accounts for a standard 3/8-inch mortar joint on all sides.

Spec	Value
Nominal size	8 in × 8 in × 16 in
Actual size	7⅝ × 7⅝ × 15⅝ in
Nominal face area	0.889 sq ft
Blocks per sq ft	1.125
Weight (normal weight)	38–43 lb
Weight (lightweight)	28–33 lb

Coverage: Blocks Per Square Foot

With a standard 3/8-inch mortar joint, one 8×8×16 cinder block covers approximately 0.889 sq ft of wall face. The inverse — blocks needed per sq ft — is 1.125.

Blocks needed = Wall area (sq ft) × 1.125

Wall area	Blocks (no waste)	+10% waste
50 sq ft	57	63
100 sq ft	113	124
150 sq ft	169	186
200 sq ft	225	248
300 sq ft	338	372
500 sq ft	563	619

Always add minimum 10% for cuts, breakage, and irregular edges. For complex walls with many corners and openings, use 15%.

Course Height Reference

Each course (horizontal row) of 8×8×16 blocks with a 3/8-inch mortar joint = 8.375 inches in total height.

Courses needed = Wall height (in) ÷ 8.375

Wall height	Courses	Actual height
2 ft (24 in)	3	25.1 in
4 ft (48 in)	6	50.3 in
6 ft (72 in)	9	75.4 in
8 ft (96 in)	12	100.5 in
10 ft (120 in)	15	125.6 in
12 ft (144 in)	18	150.8 in

Note: actual finished height will be slightly above your target. Plan bond beams, lintels, and sill heights using the actual course height (8.375 in per course), not the nominal 8 in.

Mortar Quantities

For 8×8×16 cinder blocks using 80 lb bags of pre-mixed Type S mortar:

Blocks	Bags (80 lb pre-mix)
50	4–5
100	8–9
200	17–18
300	26–27
500	43–45

Rule of thumb: 8.5 bags per 100 blocks (covers both bed joints and head joints).

Scratch-mix mortar (Type S)

For mixing from raw materials:

1 part Portland cement : 0.5 part hydrated lime : 4.5 parts masonry sand
1 bag (94 lb) Portland cement + 0.5 bag (50 lb) lime + 4.5 bags (60 lb) sand ≈ 40–50 blocks

Mortar Joint Options

Joint size	Effect on block count	Use
1/4 in	~2% more blocks/sq ft	Tight-tolerance or restoration work
3/8 in	Standard — use this	All standard cinder block walls
1/2 in	~2% fewer blocks/sq ft	Decorative variation

Other Common Cinder Block Sizes

Nominal size	Face	Blocks/sq ft	Common use
4×8×16	8×16	1.125	Interior partition walls
6×8×16	8×16	1.125	Moderate load-bearing
8×8×16	8×16	1.125	Standard structural (most common)
12×8×16	8×16	1.125	Heavy retaining walls
8×8×8	8×8	2.25	Half-block filler courses

All blocks with a nominal 8×16 face require the same 1.125 blocks per sq ft. Only the 8×8 half-block changes the coverage rate.