About this site
About My Gravel Calculator
This is a small, single-purpose tool site. It does one job — turning an area and a depth into the quantity of landscaping material you need to order — and this page explains exactly how it does that, and where the answer stops being trustworthy.
What is here
Three calculators, all free, all usable without an account:
- Gravel calculator — pea gravel, 3/4 inch crushed stone, crusher run, decomposed granite and the rest, including French drain trenches.
- Topsoil calculator — beds, raised planters, lawn levelling and top-dressing, with a coverage table by depth.
- River rock calculator — decorative stone by size grade, with coverage per ton.
Each page also carries the reference material that usually sits behind the number: coverage tables, typical depths, size guides, and answers to the questions people ask after they get a figure. The pages are plain static HTML — no sign-up, no paywall, no gated results.
How the calculators work
There is no proprietary model here, and there is nothing to trust on faith. The arithmetic is elementary geometry plus unit conversion, and it is the same arithmetic you would do on paper:
- Area. A rectangle is length × width. A circle is π × (diameter ÷ 2)². Several areas are simply added together.
- Volume. Area × depth. Every input is converted to a single internal unit first, which is why you can enter feet for the length and inches for the depth in the same calculation.
- Cubic yards. Cubic feet ÷ 27, because a cubic yard is a cube three feet on each side. Cubic metres come from the same volume using 1 ft³ = 0.0283 m³.
- Weight. Cubic yards × the density shown on the page, in US tons per cubic yard. This is the only step that involves a judgement call rather than a definition.
- Bags. Cubic feet ÷ 0.5, the most common retail bag size in North America — 54 bags to the cubic yard.
- Cost. Your own quoted price × the quantity, on whichever basis you choose. No price is pre-filled, because regional spreads are far too wide for a default to mean anything.
Any settling or compaction percentage you enter is added to the whole volume before the outputs are shown, and is capped at 50%. It is an allowance on top of the figure, not a back-calculation from a loss: if material you order loose ends up 10% smaller once it is compacted or watered in, the number that lands you back on target is 11 rather than 10. The pages that use those fields spell the conversion out.
If a block in the Area section is only half filled in — a length without a width, or a circle without a diameter — it is worth nothing to the arithmetic and the calculator says so by name instead of quietly dropping it from the total.
Where the density figures come from
Volume is exact. Weight is not, and the honest version of why is short: converting cubic yards into tons requires a density, and the density of a pile of aggregate or soil is not a constant.
The presets on each page are typical values from the ranges used across the landscape supply trade for dry, loose-delivered material — roughly 1.3–1.5 US tons per cubic yard for common gravels, 1.1–1.3 for screened topsoil, and so on. They are starting points, not measured constants and not a specification. Real material moves away from them with rock type, particle size, moisture, whether it has been washed, and how a given yard loads and settles its trucks. A difference of 10–15% is ordinary, and rained-on material can be further out than that.
This is why every density field on the site is editable rather than locked. If your supplier will tell you the tons-per-yard figure they actually bill by — most will — type it over the preset and the weight and cost lines become genuinely yours rather than typical.
The one thing worth taking away. Treat the output as a planning estimate that gets you to the right order of magnitude and a sensible order size. Confirm the final quantity with the supplier who is loading the truck, before you pay for it.
What the numbers cannot account for
- Ground that is not flat or uniform. Slopes, ruts, settlement and a subgrade that swallows the first inch of stone all pull the true quantity away from the calculated one.
- Measurement error. The result is only as good as the tape measure that produced the inputs; a foot of slop across a driveway is a meaningful number of tons.
- Local trade conventions. Some yards sell by the ton, some by the yard, some round to the half yard, and many apply delivery minimums that change what is worth ordering.
- Whether the material is the right choice. The calculator will happily size a French drain filled with crusher run, which would be the wrong stone. The written guidance on each page covers this; the arithmetic cannot.
What this site is not
It is an independent tool site, not a supplier and not a trade body. It does not sell material, does not take orders, is not affiliated with any quarry, landscape yard or retailer, and does not carry sponsored placements or affiliate links. Nothing here is engineering advice or a construction specification — for anything structural or load-bearing, the numbers you need come from a professional who has seen the site. The terms of use set this out formally.
Privacy, briefly
Every calculation runs as JavaScript in your own browser. The lengths, depths, densities and prices you type are never sent to a server, never stored, and never recorded by the site's analytics — there is no backend for them to go to. The only third-party code on these pages is Google Analytics 4, which counts page views. The full detail is in the privacy policy.
Corrections and questions
If a result looks wrong, a density seems off for your region, or something on a page is simply incorrect, that is worth telling us about — see the contact page. Corrections are the most useful mail this site gets.