PSI — pounds per square inch — is concrete's compressive strength rating at 28 days. Higher PSI resists more load and weather. Your ready-mix supplier will ask for it, and matching it to the job saves money without sacrificing durability.
PSI by project type
2,500 PSI: the practical minimum — non-structural fill and some interior slabs.
3,000–3,500 PSI: residential slabs, patios, sidewalks, and basement floors. The everyday workhorse.
4,000 PSI: driveways, garage floors, and footings — anything carrying vehicles or structural load.
4,500–5,000+ PSI: heavy-duty, commercial, and harsh freeze-thaw exposure.
PSI doesn't change the volume
Strength is about the mix, not the amount — a higher-PSI pour uses the same cubic yards, just a richer recipe. It costs a little more per yard but doesn't change the quantity you order. So size your pour with the calculator, then specify PSI when you call the supplier.
Don't forget air entrainment
In freeze-thaw climates, exterior concrete should be air-entrained — tiny air bubbles that give freezing water room to expand without spalling the surface. It's a separate spec from PSI; ask for it on any outdoor pour up north.
Common questions
What PSI concrete for a driveway?
4,000 PSI is the standard for residential driveways, with air entrainment in cold climates.
Is 3000 PSI concrete good for a patio?
Yes — 3,000 to 3,500 PSI is the normal range for patios and walkways.
Does higher PSI mean I order more concrete?
No. PSI changes the mix, not the volume. Order the same cubic yards and specify the strength.