Most sand jobs around a house are thin layers over a large area, which makes them easy to underestimate. A one inch bedding layer under a 300 square foot patio is 25 cubic feet — just under a cubic yard, and around 2,400 pounds.
Paver bedding is one inch, not more
The bedding layer under pavers should be one inch of coarse sand, screeded flat and left uncompacted before the pavers go down.
Thicker bedding is the single most common cause of a patio that goes wavy. Sand is not a base material — it will not carry load without settling. The strength comes from the compacted stone underneath, and the sand only fills the small irregularities.
Types of sand are not interchangeable
Concrete sand, sometimes sold as coarse or C-33 sand, is the correct bedding sand for pavers. The angular grains lock together.
Play sand is washed and screened fine and soft, which is why it is safe for a sandbox and wrong under pavers — it holds water and shifts.
Mason sand is finer than concrete sand and is meant for mortar.
Polymeric sand is a jointing product that goes between pavers after they are laid, not underneath them.
Bags or bulk
Bagged sand is usually 0.5 cubic feet, so a single cubic yard takes 54 bags. Anything past about half a yard is worth ordering bulk if you can.
Weight
Dry sand is about 2,600 pounds per cubic yard and wet sand can reach 3,200. Sand stored outside at a yard is almost never dry, so assume the high number when planning how to haul it.
Polymeric sand is a different product
The sand swept into paver joints at the end of a job is not the same sand that went underneath it. Polymeric sand contains a binder that sets when watered, locking the joints and resisting weeds and washout.
It is sold by the bag with its own coverage figure, which depends on joint width and paver depth rather than on area alone — a wide-jointed flagstone patio uses several times what a tight-jointed paver patio does.
It also has to be installed dry, swept completely off the paver faces, and then watered in stages. Left on the surface and wetted, it sets as a haze that is genuinely difficult to remove.
Do not use sand to level
The most common misuse of bedding sand is as a levelling medium — adding more where the base is low. It does not work, because sand is not compactable in the way a base is; it migrates under load.
Any correction of level belongs in the compacted stone base, which is the layer that carries weight. The sand layer is a uniform bedding course and it should be the same thickness everywhere.
A patio that was levelled with sand settles into a mirror of the base underneath it, usually within the first winter.