Stone Calculator for Texas Drains, Pads and Surface Courses

Cold is not what stops work in most of this state. A wet spell is. The trench you opened stays open, the pad you were shaping turns to soup, and the window you had disappears for a week. A short or wrong stone order is expensive for that reason alone, because the second delivery lands after the ground has gone off again. Most bad orders come from a handful of repeatable errors, so clear those before you touch the form.

Ordering by the wrong name, and the 5 to 10 percent nobody counts

Names first. The binding material with the fines left in is sold here as crushed limestone base, and Flex Base is what a Texas plan or a TxDOT line item will call the compacted grade. Number 57 and 57s are the same rock, and 3 quarter clean often means it too. If a plan or a permit lists a gradation, order the material named on it rather than the nearest thing on a shelf, and if the line item is hard to read, send it through the contact page before ordering rather than after.

Second, compaction. Angular stone rolled under traffic settles about 5 to 10 percent, and blends carrying fines settle more because that is what they are for. The optional 5 percent box on this page covers ordinary settling and spillage. It is not a substitute for a compacted-depth specification on engineered base work, where the finished depth is written down and the loose quantity is yours to solve.

Third, volume. Calculate a drain from the trench, not from the pipe. A 4 inch pipe in a 30-foot run displaces about a tenth of a yard, which is a wheelbarrow, and chasing that correction costs more attention than it saves.

Trench volume, not pipe volume: what actually goes in the boxes

Rectangle mode takes a length and a width in feet, which is how a pad or a drive goes in. For a trench, the length is the run and the width is the trench width, so a 14 inch trench is entered as 1.167 feet rather than 14. Circle mode takes a diameter, for a tank pad or a round hard standing. Multiple areas mode holds up to five sections and adds them, which suits a drain that changes depth partway along its run.

Depth runs from 0.25 to 24 inches. Use 2 to 3 inches for a top course, about 4 for a base layer, and 12 or more for a French drain. Pick the stone, decide about the 5 percent box, and the result comes back in cubic yards, tons and cubic feet, with an Email my quote button if you want the figures held somewhere before you commit.

Twelve graded materials and a spread of weights

Most of the crushed stock here converts at about 2,800 lb per cubic yard, which is 1.40 tons to the yard, and that figure covers #57, #67, three-quarter inch stone and the 3/8 inch chip sizes alike. Two groups sit above it. Stone screenings and dust, and #4 stone and railroad ballast, all run near 2,900 lb per yard, or 1.45 tons. Crusher run and Flex Base come in at about 3,000 lb, or 1.50, because the fines pack the voids. Armor stone is heaviest, near 3,100 lb per yard at 1.55 tons, and that is sized on the rip rap calculator.

The arithmetic is short: square feet, times depth in inches, divided by 12, gives cubic feet. Divide by 27 for cubic yards, then multiply by the figure for your material. Coverage falls out the same way. At the common 1.40 tons per yard, one ton covers roughly 116 square feet at 2 inches, about 77 at 3 inches, about 58 at 4 inches and about 39 at 6.

Lower numbers mean bigger rock, which is the part that trips people up on a first order.

Clean stone drains, stone with fines binds

Everything above falls into two families, and putting one where the other belongs is the error that costs a whole job rather than a few tons.

Clean washed stone such as #57 Limestone, #67 Stone or 3/4" Crushed Stone stays open, and water moves through the voids between pieces. That is what a French drain, a pipe surround or a drainage bed behind a wall needs. Drain Rock is the same idea sold for that purpose.

Stone carrying fines is the opposite. Crusher Run and Flex Base lock up tight when they are rolled, which is what a base under load wants and exactly what you do not want in a drain. Put crusher run in a French drain and you have built a dam. Put clean #57 under a driveway with no binder and the surface keeps moving under the tires. On a new drive the usual arrangement is 3 to 4 inches of compacted base with 2 to 3 inches of #57 or driveway gravel over the top, and each layer is its own run of the calculator. Base depths for lanes and pads are worked out on the road base calculator.

Stone Screenings sit between the two. They screed flat and firm up under a plate, which makes them a bedding layer over a compacted base rather than a base in their own right.

A 52-foot drain line and a pad the feeder sits on

Two hypothetical jobs, worked through so you can check the tool against them.

A French drain taking roof and yard water out to a ditch runs 52 feet, with a trench 14 inches wide and 16 inches of #57 Limestone in it. Width in feet is 14 / 12 = 1.167, so the area is 52 x 1.167 = 60.67 square feet. Cubic feet: 60.67 x 16 / 12 = 80.89. Cubic yards: 80.89 / 27 = 3.00. Tons: 3.00 x 1.40 = 4.19. Wrap the trench in non-woven fabric before the stone goes in, because the fine clay that dominates much of this state will silt the voids closed within a couple of seasons otherwise.

A hard standing where a feeder or a hay ring sits, 26 by 16 feet with 6 inches of Railroad Ballast so it drains while cattle and a tractor work it: 416 square feet, 416 x 6 / 12 = 208 cubic feet, 208 / 27 = 7.70 cubic yards, 7.70 x 1.45 = 11.17 tons. With the 5 percent box ticked, 8.09 cubic yards and 11.73 tons.

Getting the load in while the ground is still dry

Delivery is arranged at checkout by ZIP code, so set the drop spot before you book. The spot matters twice over here, because a pile in the wrong place means wheelbarrowing across the exact ground you are trying to keep firm. Put it on hard standing near the trench head or the pad edge, leave the truck a clear way out, and have fabric and pipe on site first. Take the tonnage to the product page and set a quantity and a date. For job-named material rather than a graded number, the gravel calculator covers driveway and decorative work.

Common questions

Related calculators