Mix ratios, cure times, and bag counts for slabs, footings, and driveways.
Doing this on a real job? Pour a concrete slab: materials, tools and steps sized to your numbers.
Get the planBasement walls or slab leaking? Diagnose it and size the fix with the basement waterproofing cheat sheet.
Pouring piers? Get bags per tube and cubic yards with the sonotube concrete calculator.
How long before you can use new concrete (standard mix at 70 F)
Enter a pour date and a temperature between 20 and 120 F.
| Age | 50 F | 70 F | 90 F |
|---|---|---|---|
| 1 day | 10% | 20% | 28% |
| 3 days | 25% | 40% | 50% |
| 7 days | 45% | 65% | 72% |
| 14 days | 65% | 85% | 88% |
| 28 days | 85% | 100% | 98% |
Approximate percent of 28-day design strength for a standard mix kept moist. Hot weather gains early strength but often ends a little lower.
| Use | PSI | Cement : sand : gravel | Water-cement ratio | Slump | Air entrainment |
|---|---|---|---|---|---|
| Footings and foundations | 2500 to 3000 | 1 : 2.5 : 3.5 | 0.55 to 0.60 | 4 to 5 in | Not needed below grade |
| Slabs, patios, sidewalks | 3000 to 3500 | 1 : 2 : 3 | 0.50 | 4 in | 5 to 7% in freeze-thaw areas |
| Driveways, garage floors | 4000 | 1 : 1.5 : 3 | 0.45 | 3 to 4 in | 5 to 7% in freeze-thaw areas |
| High strength (heavy loads) | 4500+ | 1 : 1.5 : 2.5 | 0.40 | 3 to 4 in | As specified |
Code minimums (IRC R402.2): 2500 PSI where weathering is negligible, 3000 PSI for moderate, and 3500 PSI air-entrained for porches, steps and garage floors in severe freeze-thaw areas. Water: about 3 qt per 80 lb bag; every extra quart makes it weaker and more likely to crack. Mix by the yard with the concrete mix calculator.
| Time | Strength | Activity |
|---|---|---|
| 24-48 hours | ~20% | Initial set, walk on carefully |
| 3 days | ~40% | Light loads |
| 7 days | ~65-70% | Cars, keep curing |
| 28 days | 100% | Design strength, heavy loads, seal or stain |
| 90 days | 100%+ | Continued hardening |
Sidewalks: 4 inches minimum
Patios: 4 inches minimum
Driveways (Cars): 4-6 inches
Driveways (Heavy Trucks): 6-8 inches
Garage Floors: 6 inches minimum
Basement Floors: 4 inches over gravel base
Rebar
Wire Mesh
Fiber Mesh
1. Screeding
Level concrete with screed board
2. Bull Floating
Smooth surface, embed aggregate
3. Edging
Round edges to prevent chipping
4. Control Joints
Cut to 1/4 of slab depth, every 2 to 3 times the thickness in feet (see the joint table below)
5. Troweling
Smooth finish after bleed water evaporates
6. Brooming
Add slip resistance for outdoor surfaces
1 Cubic Yard = 27 cubic feet
4" Slab: 1 cubic yard covers 81 sq ft
5" Slab: 1 cubic yard covers 65 sq ft
6" Slab: 1 cubic yard covers 54 sq ft
80 lb Bag: Makes 0.6 cubic feet
60 lb Bag: Makes 0.45 cubic feet
40 lb Bag: Makes 0.30 cubic feet
| Bag | Yield | Bags per cu yd | 10 x 10 ft slab, 4 in | Water |
|---|---|---|---|---|
| 40 lb | 0.3 cu ft | 90 | 112 | 1.5 qt |
| 50 lb | 0.375 cu ft | 72 | 89 | 1.9 qt |
| 60 lb | 0.45 cu ft | 60 | 75 | 2.3 qt |
| 80 lb | 0.6 cu ft | 45 | 56 | 3.0 qt |
Same yields for standard, high early, fast-setting and crack-resistant mixes; mortar and sand mixes yield less. For your exact pour use the concrete calculator, footing calculator, concrete stairs calculator or column calculator.
| Slab | Joint spacing | Joint depth |
|---|---|---|
| 4 in | 8 to 12 ft | 1 in |
| 5 in | 10 to 15 ft | 1-1/4 in |
| 6 in | 12 to 15 ft | 1-1/2 in |
Rule: 2 to 3 times the thickness in feet, depth 1/4 of the slab, and panels no longer than 1.5 times their width. Cut within 6 to 18 hours.
This concrete mixing and pouring cheat sheet provides essential reference information for DIY concrete projects including sidewalks, patios, driveways, footings, and slabs. Understanding concrete mix ratios, slab thickness requirements, reinforcement needs, and proper curing techniques is crucial for durable, long-lasting results.
Concrete work is unforgiving - once poured, you have limited time to finish before it sets, and mistakes are difficult to correct. This guide helps you plan your project properly, from calculating material quantities to understanding strength development timelines. Proper preparation, including correct reinforcement and adequate curing, makes the difference between concrete that lasts decades and concrete that cracks within the first year.
Whether you're pouring a small pad for an AC unit or a full driveway, the fundamentals remain the same: correct mix design, proper thickness, adequate reinforcement, good finishing technique, and thorough curing. This reference provides the specifications you need to get each of these elements right.
Having quick access to concrete specifications helps ensure your project will be strong enough for its intended use and will resist cracking and deterioration over time.
Finishing the slab? See concrete staining and stamping, driveway repair and sealing, paver patio installation, retaining walls and masonry joint types.
Ask about your situation. Posting needs a free account, and your question carries over so you get an answer with your project in view. Questions we hear often get answered on this sheet.
Cubic yards, bags and cost for slabs, footings, walls, columns, stairs and curbs
Draw any slab shape and get a full materials list, tools, cost, and step-by-step plan
Cement, sand, gravel and water for any mix ratio or PSI, plus premix bag counts
Stain coverage and cost calculator, how to recolor stamped concrete, stain vs paint vs dye vs overlay, stamping timing, troubleshooting and FAQs
Sealer calculator, crack identifier, repair vs replace table, sealer types, timing and cure, 8-step checklist and FAQ
Block selection, base preparation, drainage requirements, and height limitations