10 square yards to square feet

Ten square yards is 90 square feet, and the factor is fixed

Ten square yards is 90 square feet. The step is a definition rather than a measurement: a yard is three feet, a square yard is the ground inside a frame three feet on each side, and that frame holds 3 x 3 = 9 square feet. Ten frames hold 90.

Outside the yardstick world the same ground is 12,960 square inches and 8.3612736 square meters. The inch figure is 1,296 square inches per square yard, counted ten times. The metric figure starts from the legal yard of 0.9144 m agreed in 1959. Squared, that gives 0.836 127 36 square meters per square yard, and ten of those is 8.3612736.

NIST Special Publication 811, 2008 edition prints the yard as exactly 0.9144 m and the square yard as 8.361 274 E-01 square meters, and it records that the 1959 agreement replaced the older 3600/3937 m definition. That history matters in one narrow way: a drawing made against the old US survey foot will sit a couple of parts per million away from the figure here, which over 90 square feet is less than a grain of sand.

Read any row across and you are looking at one piece of ground in four units. The 20 square yard row is the 180 square foot row, which is also 25,920 square inches and 16.7225 square meters.

Outlines that hold 90 square feet

Area does not care about outline. A 9 foot by 10 foot pad is 90 square feet, and so are a 6 by 15 foot rectangle, a 7.5 by 12 foot one, a strip 5 feet wide and 18 feet long, and a square with sides of 9.4868 feet, since 9.4868 x 9.4868 = 90.

Ten square yards is a small hardscape. A bench and two chairs fit with room to walk; a car does not, unless the pad runs about 6 by 15 feet and you accept that both doors open over the grass. That size turns up as shed bases, bin pads, hot tub surrounds, and the landing at the foot of deck stairs.

Measure the ground that will be covered, not the frame that will sit on it. A pad edged with 2 inch boards loses a little surface to the timber, and a pad cut into a slope shows more stone on the downhill side than a plan view suggests. Neither error is large on 90 square feet, but both show up as a short load.

Worked example: gravel under a 9 by 10 pad

Start with the area and the compacted depth. Ninety square feet at 4 inches is 90 x 4 / 12 = 30 cubic feet, and 30 / 27 = 1.111 cubic yards. In half cubic foot sacks that is 60, and at an example density of 1.35 tons per cubic yard the load weighs 1.5 tons.

Six inches changes only the depth term: 90 x 6 / 12 = 45 cubic feet, 1.667 cubic yards, 90 sacks, 2.25 tons. Two inches gives 15 cubic feet, 0.556 cubic yards, 30 sacks and 0.75 tons.

The Oregon State University Extension Service guide to installing pavers asks for four to six inches of compacted crushed rock under the pavers, one inch of bedding sand on top of it, and the rock placed in layers with compaction between them rather than in one lift. The depth in that guide is measured after compaction, so a yard quoting loose volume is quoting a bigger pile than the hole in the ground.

The sack column is the one to hold against a shelf tag. A store selling 0.5 cubic foot sacks and a yard selling by the ton are pricing different things: 1.111 cubic yards is 1.5 tons of stone, and the same stone in 60 sacks is a pallet and a half. Buy whichever is cheaper per cubic yard after delivery.

Worked example: the bill at a price per square yard

Tags in this trade are written per square yard often enough that the conversion is worth doing once. At $6.50 per square yard the same work is $0.72 per square foot and $72.22 per 100 square feet. Ten square yards at that tag is $65.00.

Add a cut allowance and the number moves. A 10 percent allowance takes the order from 10 square yards to 11, or from 90 square feet to 99, and the bill from $65.00 to $71.50. A 5 percent allowance, which is what Oregon State suggests when the outline is mostly straight, lands at 94.5 square feet, or 10.5 square yards.

Two questions keep a quote honest. Ask whether the price includes delivery, because 1.5 tons of stone is not a car boot load, and ask whether the per square yard figure assumes compacted depth. A tag that looks $2 cheaper per square yard can lose that advantage in one extra trip.

Watch the rounding. $6.50 divided by 9 is 0.722222, which prints as $0.72. Multiplying that rounded figure by 90 gives $64.80, while the true cost is $65.00. Round the final bill, not the factor.

The hole is deeper: base, sand and paver

The hole is deeper than the stone. Add the base, the bedding sand and the paver: 4 + 1 + 2.375 = 7.375 inches for a 60 mm paver. Over 90 square feet that is 90 x 7.375 / 12 = 55.3125 cubic feet, or 2.05 cubic yards of spoil to dig, wheelbarrow and get rid of.

The sand layer alone is 90 x 1 / 12 = 7.5 cubic feet, a bit over a quarter of a cubic yard. A 6 inch base raises the total to 9.375 inches and 70.3125 cubic feet, or 2.6 cubic yards, which is enough to fill a small trailer twice.

Oregon State adds two allowances that are easy to skip. Five percent goes onto the paved area for cuts, and 10 percent where the outline curves a lot. On 90 square feet the 5 percent figure is 4.5 square feet, one more row of pavers, and the 10 percent figure is 9 square feet.

Stone is sold by volume but weighed on the way out, and wet stone weighs more than dry. If the ticket is in tons, use the density printed on it rather than the 1.35 used here, which is only a placeholder for crushed rock in the 3/4 inch range.

The Iowa State University Extension article on installing pavers, published in 1995, runs the same sum for a thicker build: 5 inches of base, 1.5 inches of sand and a 3.5 inch paver comes to 10 inches of soil to remove. Over 90 square feet that is 75 cubic feet, or 2.778 cubic yards.

Metric, acres and the decimal shift

Multiplying by 9 is the whole conversion, and at 10, 100 and 1,000 square yards the answer arrives without a calculator: 90, 900 and 9,000 square feet. Going back, dividing by 9 turns 900 square feet into 100 square yards and 45 square feet into 5.

Metric is less friendly. Ten square yards is 8.3612736 square meters, and a tidy 3 m by 3 m metric pad is 9 square meters, which is 96.88 square feet, or 10.76 square yards. That is close enough to ten square yards that a plan drawn in metres and a quote written in yards can be compared after one step.

Acres sit far above this scale. An acre is 43,560 square feet, or 4,840 square yards, so 10 square yards is 0.002066 acre, about one part in 484. Nobody buys a pad in acres, but the figure appears when a landscape plan prices a whole lot in square yards and one bed in acres.

Square inches rarely help outdoors, but they help indoors. At 12,960 square inches, a tile sold at 144 square inches per piece needs 90 pieces for the area before any cuts, which is the same count as the 90 square feet the pad started with.

Five places a ten square yard order loses material

Measuring the frame, not the fill. A 9 by 10 frame of 2 inch boards leaves 8.67 by 9.67 feet inside, which is 83.8 square feet, or 9.3 square yards.

Treating 30 cubic feet as a cubic yard. A cubic yard is 27 cubic feet, so 30 cubic feet is 1.111 cubic yards. Ordering one yard leaves a ninth of the pad short.

Mixing loose and compacted volume. Crushed rock settles under a plate compactor, so the depth to buy against is the depth after compaction, not the depth of the pile.

Rounding 90 down. Ninety square feet is the figure. Eighty square feet is 8.9 square yards and a visible gap along one edge.

Forgetting the sand. The bedding layer is 7.5 cubic feet at one inch, and it is a separate line on the ticket from the base rock.

Write four numbers on the order sheet: 10 square yards, 90 square feet, 1.111 cubic yards at four inches, and 1.5 tons at the density the yard quotes. Anything else is a guess wearing a decimal point.