Sod is the one material on this site with a clock on it. It is cut to order, it is heavy, and it starts dying the moment it leaves the field, so the number you want is the one you can lay the day it arrives. This sod calculator takes the lawn, adds the cutting allowance, and tells you how many pieces to order.
What one piece covers is the figure to get right
Everything else here is arithmetic. This one number comes from the grower, because the cutting machine sets it and machines differ.
Purdue Extension puts a slab at about 18 by 24 inches, which is 3 square feet, and a roll at either 18 inches by 6 feet or 24 inches by 5 feet, which is 9 or 10. Virginia Cooperative Extension describes the standard roll as approximately 10 square feet. That 10 is the default above, and it is the right starting point for most of the country, but it is a default and not a fact about your order.
Pallets are not a unit of measure
Ordering “two pallets” is how most people start and it is the easiest way to end up short. Mississippi State Extension says a pallet typically holds 450 to 500 square feet. Virginia puts the range wider, at 450 square feet, which is 50 square yards, up to 700 square feet. Purdue gives about 50 square yards.
So a pallet is somewhere between 450 and 700 square feet depending on who grew it. Work in square feet, get the piece count above, and let the grower tell you how that lands on pallets.
The allowance is for cuts, not breakage
Sod does not break in transit the way brick does. The waste is the offcut left over every time a piece meets a curve, a bed, a path or a tree ring, and it scales with how complicated the edge is rather than with the area.
Purdue recommends ordering about 10 percent more than you expect to need, covering both measurement error and cutting around corners and edges. Mississippi State suggests about 5 percent. Ten is the default here; drop it toward five on a plain rectangle with straight edges, and leave it at ten or above on anything with curves.
Square yards, square feet
Growers usually quote by the square yard and you almost certainly measured in feet. One square yard is 9 square feet, so 1,000 square feet is about 111 square yards. To turn a square yard price into the price per piece this calculator asks for, divide it by nine and multiply by the coverage of one piece.
Order for the day you can lay it
Weight is the part people underestimate. Virginia gives dry sod at 20 to 25 pounds per square yard and wet sod at 30 to 40. Mississippi State notes that a 450 square foot pallet may weigh as much as a ton.
That is a real constraint on the order rather than a note at the end. A lawn that takes three pallets is three tons arriving at once, it has to come off the truck, and it wants to be on soil the same day. If you cannot lay it all in a day, order it in deliveries you can keep up with rather than stacking the rest in the driveway.