Every slab size, priced at 4 inches

111 sizes, grouped by area. Each row is the volume at 4 in thick and the 80 lb bag count rounded up. Something not on the list? Type it into the slab calculator.

The line runs at 1.33 yd³

Where bagging stops paying

Bag it up to

1.33 cubic yards

60 bags of 80 lb · 36 cubic feet · the largest slab that bags at 4 in is 6 × 18 ft

Read the Buy as column. Everything tagged Bags is under 60 bags of 80 lb and mixes in an afternoon. Everything tagged Ready-mix is a phone call to a plant, and the tag changes at the same 1.33 cubic yards on every page of this site.

All 111, by area

The sizes

The bands are the two decisions, not round numbers: the first ends where bagging stops paying at 108 ft², and the last begins at 750 ft², where the ordered volume at 4 in passes ten cubic yards and a second truck is needed.

Under 110 ft² — 18 sizes

Shed pads, air-conditioner pads, a step landing. The last row is the crossover itself: 6 × 18 ft is exactly 60 bags of 80 lb.

Under 110 ft², at 4 in thick. The arrow figure is the same bag count with 10% waste
Slab	Area ft²	Cubic yards	80 lb bags→ with 10% waste	Buy as
4 × 4 ft	16	0.20	9→10	Bags
4 × 6 ft	24	0.30	14→15	Bags
4 × 8 ft	32	0.40	18→20	Bags
6 × 6 ft	36	0.44	20→22	Bags
4 × 10 ft	40	0.49	23→25	Bags
4 × 12 ft	48	0.59	27→30	Bags
6 × 8 ft	48	0.59	27→30	Bags
4 × 14 ft	56	0.69	32→35	Bags
6 × 10 ft	60	0.74	34→37	Bags
4 × 16 ft	64	0.79	36→40	Bags
8 × 8 ft	64	0.79	36→40	Bags
6 × 12 ft	72	0.89	40→44	Bags
8 × 10 ft	80	0.99	45→49	Bags
6 × 14 ft	84	1.04	47→52	Bags
6 × 16 ft	96	1.19	54→59	Bags
8 × 12 ft	96	1.19	54→59	Bags
10 × 10 ft	100	1.23	56→62	Bags
6 × 18 ft	108	1.33	60→66	Bags

110 to 199 ft² — 15 sizes

Hot-tub pads and small patios. Past the bag line from the first row, and one truck covers all of them.

110 to 199 ft², at 4 in thick. The arrow figure is the same bag count with 10% waste
Slab	Area ft²	Cubic yards	80 lb bags→ with 10% waste	Buy as
8 × 14 ft	112	1.38	63→69	Ready-mix
6 × 20 ft	120	1.48	67→74	Ready-mix
10 × 12 ft	120	1.48	67→74	Ready-mix
8 × 16 ft	128	1.58	72→79	Ready-mix
10 × 14 ft	140	1.73	78→86	Ready-mix
6 × 24 ft	144	1.78	80→88	Ready-mix
8 × 18 ft	144	1.78	80→88	Ready-mix
12 × 12 ft	144	1.78	80→88	Ready-mix
8 × 20 ft	160	1.98	89→98	Ready-mix
10 × 16 ft	160	1.98	89→98	Ready-mix
12 × 14 ft	168	2.07	94→103	Ready-mix
10 × 18 ft	180	2.22	100→110	Ready-mix
8 × 24 ft	192	2.37	107→118	Ready-mix
12 × 16 ft	192	2.37	107→118	Ready-mix
14 × 14 ft	196	2.42	109→120	Ready-mix

200 to 399 ft² — 23 sizes

One-car pads, single driveways, workshop floors. Still one truck.

200 to 399 ft², at 4 in thick. The arrow figure is the same bag count with 10% waste
Slab	Area ft²	Cubic yards	80 lb bags→ with 10% waste	Buy as
8 × 25 ft	200	2.47	112→123	Ready-mix
10 × 20 ft	200	2.47	112→123	Ready-mix
12 × 18 ft	216	2.67	120→132	Ready-mix
14 × 16 ft	224	2.77	125→137	Ready-mix
8 × 30 ft	240	2.96	134→147	Ready-mix
10 × 24 ft	240	2.96	134→147	Ready-mix
12 × 20 ft	240	2.96	134→147	Ready-mix
10 × 25 ft	250	3.09	139→153	Ready-mix
14 × 18 ft	252	3.11	140→154	Ready-mix
16 × 16 ft	256	3.16	143→157	Ready-mix
14 × 20 ft	280	3.46	156→172	Ready-mix
12 × 24 ft	288	3.56	160→176	Ready-mix
16 × 18 ft	288	3.56	160→176	Ready-mix
10 × 30 ft	300	3.70	167→184	Ready-mix
12 × 25 ft	300	3.70	167→184	Ready-mix
16 × 20 ft	320	3.95	178→196	Ready-mix
18 × 18 ft	324	4.00	180→198	Ready-mix
14 × 24 ft	336	4.15	187→206	Ready-mix
14 × 25 ft	350	4.32	195→214	Ready-mix
10 × 36 ft	360	4.44	200→220	Ready-mix
12 × 30 ft	360	4.44	200→220	Ready-mix
18 × 20 ft	360	4.44	200→220	Ready-mix
16 × 24 ft	384	4.74	214→235	Ready-mix

400 to 749 ft² — 25 sizes

Two-car garages, large patios, short driveways. The last size that fits one truck at 4 in is in this band.

400 to 749 ft², at 4 in thick. The arrow figure is the same bag count with 10% waste
Slab	Area ft²	Cubic yards	80 lb bags→ with 10% waste	Buy as
10 × 40 ft	400	4.94	223→245	Ready-mix
16 × 25 ft	400	4.94	223→245	Ready-mix
20 × 20 ft	400	4.94	223→245	Ready-mix
14 × 30 ft	420	5.19	234→257	Ready-mix
12 × 36 ft	432	5.33	240→264	Ready-mix
18 × 24 ft	432	5.33	240→264	Ready-mix
18 × 25 ft	450	5.56	250→275	Ready-mix
12 × 40 ft	480	5.93	267→294	Ready-mix
16 × 30 ft	480	5.93	267→294	Ready-mix
20 × 24 ft	480	5.93	267→294	Ready-mix
20 × 25 ft	500	6.17	278→306	Ready-mix
14 × 36 ft	504	6.22	280→308	Ready-mix
18 × 30 ft	540	6.67	300→330	Ready-mix
14 × 40 ft	560	6.91	312→343	Ready-mix
16 × 36 ft	576	7.11	320→352	Ready-mix
24 × 24 ft	576	7.11	320→352	Ready-mix
20 × 30 ft	600	7.41	334→367	Ready-mix
24 × 25 ft	600	7.41	334→367	Ready-mix
25 × 25 ft	625	7.72	348→382	Ready-mix
16 × 40 ft	640	7.90	356→392	Ready-mix
18 × 36 ft	648	8.00	360→396	Ready-mix
14 × 50 ft	700	8.64	389→428	Ready-mix
18 × 40 ft	720	8.89	400→440	Ready-mix
20 × 36 ft	720	8.89	400→440	Ready-mix
24 × 30 ft	720	8.89	400→440	Ready-mix

750 ft² and over — 30 sizes

Barn floors, RV pads, long driveways. At 4 in the ordered volume passes ten cubic yards here, so every one of these needs a second truck and a placing plan.

750 ft² and over, at 4 in thick. The arrow figure is the same bag count with 10% waste
Slab	Area ft²	Cubic yards	80 lb bags→ with 10% waste	Buy as
25 × 30 ft	750	9.26	417→459	Ready-mix
16 × 50 ft	800	9.88	445→489	Ready-mix
20 × 40 ft	800	9.88	445→489	Ready-mix
24 × 36 ft	864	10.67	480→528	Ready-mix
18 × 50 ft	900	11.11	500→550	Ready-mix
25 × 36 ft	900	11.11	500→550	Ready-mix
30 × 30 ft	900	11.11	500→550	Ready-mix
16 × 60 ft	960	11.85	534→587	Ready-mix
24 × 40 ft	960	11.85	534→587	Ready-mix
20 × 50 ft	1,000	12.35	556→612	Ready-mix
25 × 40 ft	1,000	12.35	556→612	Ready-mix
18 × 60 ft	1,080	13.33	600→660	Ready-mix
30 × 36 ft	1,080	13.33	600→660	Ready-mix
20 × 60 ft	1,200	14.81	667→734	Ready-mix
24 × 50 ft	1,200	14.81	667→734	Ready-mix
30 × 40 ft	1,200	14.81	667→734	Ready-mix
25 × 50 ft	1,250	15.43	695→764	Ready-mix
36 × 36 ft	1,296	16.00	720→792	Ready-mix
24 × 60 ft	1,440	17.78	800→880	Ready-mix
36 × 40 ft	1,440	17.78	800→880	Ready-mix
25 × 60 ft	1,500	18.52	834→917	Ready-mix
30 × 50 ft	1,500	18.52	834→917	Ready-mix
40 × 40 ft	1,600	19.75	889→978	Ready-mix
30 × 60 ft	1,800	22.22	1,000→1,100	Ready-mix
36 × 50 ft	1,800	22.22	1,000→1,100	Ready-mix
40 × 50 ft	2,000	24.69	1,112→1,223	Ready-mix
36 × 60 ft	2,160	26.67	1,200→1,320	Ready-mix
40 × 60 ft	2,400	29.63	1,334→1,467	Ready-mix
50 × 50 ft	2,500	30.86	1,389→1,528	Ready-mix
50 × 60 ft	3,000	37.04	1,667→1,834	Ready-mix

Not on the list

3 other ways in

All 111 slab sizesArea, yards at 4 in and 80 lb bags, no typing Any dimensionsType a width, a length and a thickness How to measureBefore you trust any of these numbers

About this table

Questions

Bags or ready-mix — where is the line?

Around 60 bags of 80 lb, which is 36 cubic feet or 1.33 cubic yards. Under that you can mix it in a day with a rented mixer and one helper, and you pay only for what you open. Over it you are buying several pallets, handling two tons or more by hand, and racing the set on the first batch you placed. Some plants charge a short-load fee below about 3 yards, so ask when you book.

How many 80 lb bags are in a cubic yard?

45, and you buy 45. An 80 lb bag of mix yields about 0.60 cubic feet once water is in it, and a cubic yard is 27 cubic feet. A 60 lb bag yields about 0.45 cubic feet, so 60 of those make a yard. Every bag count on this site is rounded up, because a store will not sell you nine tenths of a bag.

Where exactly do I measure thickness from?

From the top of the compacted gravel base to the finished surface of the slab. The gravel is not concrete, and the mistake is expensive: one inch of it counted as concrete on a 20 × 20 ft slab is 1.23 cubic yards. Compact the base, set a stake to the finished height, and measure down from that.

How much extra should I order?

10 percent, and where it appears depends on what you are buying. Ready-mix carries it inside the ordered figure, because a truck will not come back for a quarter yard. Bag counts do not: the headline count is the volume, and the plus figure sits beside it, because bags are bought one at a time and an unopened one goes back. Either way the allowance covers spillage, a base that is not perfectly flat and the thickness you gain at the edges of the form.

What is a mixer-truck load?

A full truckload is typically about 10 cubic yards, and that is the figure this site plans with. Ask when you book: drums vary, and a plant will tell you what it is sending. The load count here is worked from the ordered volume — the one that already includes the 10% allowance — because that is what actually has to fit on the truck.

Does this include rebar, forms or labour?

No. The price band is concrete delivered: your own price per yard on the ordered volume, taken 15% either side of the middle to cover what a quote actually varies by. Forms, gravel, mesh or bar, a pump if the truck cannot reach, and finishing are all separate. Get the plant to quote your postcode before you budget.

Bag yields: QUIKRETE Concrete Mix data sheet No. 1101. Price basis: Concrete Financial Insights weighted average selling price for 2025, escalated with U.S. Bureau of Labor Statistics PPI series PCU327320327320 (2026-07). Prices vary by region — enter your own quote above.