What a calculator here is#
A QuantiYard calculator turns measurements you already have into the unit your supplier actually sells in.
That is the whole scope. Cubic yards of concrete, tons of stone, gallons of paint, boxes of flooring, squares of siding, pounds of fertiliser. The hard part of a material estimate is rarely the geometry. It is knowing that a face cord has no fixed volume, that carpet is priced off a roll rather than off a floor, or that a nitrogen rate and a bag of fertiliser are in different units. Each page carries the one piece of trade knowledge that makes its answer right, and states it.
Nothing here is behind a sign-up, and nothing here needs an account. There is no saved data because there is nothing to save: every calculation happens in your browser and never reaches a server.
Where the formulas come from#
Most of them are geometry. Volume is length by width by depth. A cubic yard is 27 cubic feet. A roof's area is its footprint times a pitch multiplier, which is the square root of rise squared plus 144, divided by 12. None of that needs a citation, and it is written out on the page so you can check it against your own arithmetic rather than trusting the box.
Where a formula is not geometry, it is trade practice, and the page says which trade practice. The gutter calculator sizes off the horizontal footprint rather than the sloped roof, because rain falls vertically and a 12/12 roof collects exactly what a flat roof on the same footprint does. The carpet calculator tries the layout both ways round and keeps whichever buys less carpet. Those are decisions, not conversions, and every one of them is explained where it is used.
Every formula was checked by hand against a known reference case before it shipped, and the worked example is recorded so a later change can be checked against the same case.
Where the constants come from#
Three places, and each calculator's own sources block names which one applies to it.
Printed on the package. Bag yields, spread rates and coverage figures. An 80 lb bag of concrete mix yields 0.60 cubic feet, a 60 lb bag 0.45, a 40 lb bag 0.30. Paint covers about 350 square feet a gallon. These are the manufacturer's own numbers and the bag in your hand outranks this site.
A published standard. A small number of pages rest on something with a name and an edition. The insulation calculator uses the ENERGY STAR recommended R-values from 2021 IECC Table R402.1.3, with R per inch and bag coverage from manufacturer charts including Owens Corning AttiCat and Greenfiber. The stair calculator checks against the 2021 IRC limits of a 7 3/4 inch maximum riser and a 10 inch minimum tread. The gutter calculator uses SMACNA pitch factor bands. The deck joist span chart reproduces AWC DCA 6 Table 2, read from the published PDF rather than a secondary summary.
An industry average. Everything else, and this is the largest group. Material densities, mortar per brick, screws per sheet. Where a figure is an average, the page says so instead of implying a source it does not have. The excavation calculator goes a step further and prints the pounds per cubic foot its tonnages are derived from, so the arithmetic can be checked rather than taken.
A constant nobody published is not a weakness as long as the page admits it. The failure mode worth avoiding is a citation that sounds authoritative and cannot be looked up, which is why no page here carries one.
How waste factors are chosen#
A waste factor is an estimate of what the cutting pattern destroys, and it is set per material rather than picked once for the site.
Flooring defaults to 10 percent on a straight layout and 15 on a diagonal, because a diagonal cut leaves a triangle nothing else uses. Baseboard defaults to 15 rather than 10, because a coped inside corner and a mitred outside corner both leave nothing usable where a flooring offcut leaves a strip. Roofing runs 10 on a simple roof and 15 on a cut-up one. Sod runs 5 on a rectangle and 10 on an irregular lawn. Every one of those is editable, and every page says which way to push it.
Waste is also applied to the right thing. On the paver calculator it applies to the paver count only, for cuts and breakage, and not to the base or the bedding sand, which are poured to a depth and do not care about the cutting pattern. On the carpet calculator it applies to the drop length rather than the area, because that is where the trim allowance is.
Which way a number rounds#
Anything sold in whole units rounds up: bags, boxes, sheets, pieces, pails. That rounding runs through one shared helper rather than a bare ceiling, because a waste multiplier can land a hair above a round number in binary floating point. A hundred tiles at 10 percent waste computes to 110.00000000000001, and a bare ceiling turns that into 111. Rounding the fuzz off first is why a 10 by 10 room of 12 by 12 inch tile quotes 110 tiles.
Two pages round down, on purpose. The rebar calculator rounds bar counts down because grid spacing is a maximum: a slightly narrow last bay is the safe side, and rounding up would put a bar past the clearance line. The wallpaper calculator rounds strips per roll down, because a strip two inches short is waste rather than a strip.
Where rounding up costs real money, the page shows what the rounding bought. Plywood and driveway sealer both report coverage bought alongside coverage needed, because a sheet you do not use is still a sheet you paid for.
How prices are sourced and reviewed#
Prices appear in the cost and comparison guides, never inside a calculator's formula. A calculator's optional price field multiplies by whatever number you type into it, so nothing on a calculator page can go stale.
Guide prices are 2026 US national ranges, compiled from published contractor and industry cost data and cross-checked against multiple homeowner cost surveys. Each guide names its sources in its own method note. All eighteen were written in September 2026 and share a vintage, which is recorded rather than left to be guessed at, and they are scheduled for a full recheck in January 2027, ahead of the spring project season.
Where a chart or a saved image quotes the same work as a guide, the guide's own itemised table is the source and the image is generated from it. That is enforced rather than remembered: the build refuses to ship an image carrying a number that does not appear in the guide it cites.
Code and standards pages#
Two pages reproduce published code and are held to a higher bar than the rest of the site, because a wrong figure there has consequences past a bad material order.
Stair code requirements reproduces 2021 International Residential Code minimums, checked against the IRC Code and Commentary rather than recalled or taken from a secondary summary. The edition is named on the page and every dimension carries its section number. The deck joist span chart reproduces AWC DCA 6 Table 2, read from the published PDF, with the table's own footnotes alongside it.
Both pages report published minimums, cite the section, and stop. Your jurisdiction adopts an edition and may amend it, amendments to the stair section in particular are common, and anything outside the ordinary cases belongs with an engineer. Where a figure could not be verified to that standard it is left off the page rather than published with a hedge, which is why the joist span chart carries deck joists and no floor joists.
What these deliberately do not do#
The list is as much a part of the method as the formulas.
- No structural design. Nothing here sizes a beam, a header, a post, a footing or a load path. The framing calculator counts the studs in a wall with openings in it and says plainly that it does not size the headers over them.
- No load calculations. The BTU calculator is a rule of thumb from floor area, climate, ceiling height and sun. Real equipment is sized with an ACCA Manual J calculation, which accounts for insulation, windows and air sealing, and the page says so on the result card.
- No permit or code advice. A retaining wall over 4 feet generally needs a permit and an engineered design, and any wall holding a slope needs engineering at any height. The retaining wall calculator flags that above the calculator so it is read before any number is.
- No soil, drainage or geotechnical work. The excavation calculator converts volumes and weights. It does not tell you whether a slope will stand up.
- No substitute for the supplier. Densities vary with moisture, coverage varies by manufacturer, and pallet and roll sizes vary by supplier. On a large order, the quote in your hand beats the estimate on your screen.
How the site checks itself#
Reading a page carefully catches a mistake once. A check catches it every time, so most of what this site knows about itself is written down as a test that runs before anything ships.
One command runs them all. Every page must carry its analytics tag in the right place and self-reference its own clean URL. Every schema question and answer must appear word for word in the visible text of the page, so structured data can never claim something a reader cannot see. Every internal link and image source must resolve to a real file, every declared social card must exist on disk, and every URL named anywhere in a page's structured data must resolve too. The sitemap and the repository must agree in both directions. Every guide must link at least two calculators at least twice each. Every number printed on a chart must appear in the page or the calculation it was taken from. And a separate check reads the live site after a deploy, because everything the others prove, they prove about files rather than about what a visitor was actually served.
Reporting an error#
If a formula, a default or a coverage rate does not match what you are seeing in the field, that is worth knowing about, and a specific report is worth far more than a general one. The most useful message names the page, the numbers you put in, the number you got, and the number you expected.
Write to hello@quantiyard.com, or see the contact page for what else to send there and how long a reply takes. A correction to a calculator gets fixed and re-verified against a hand-worked case before it goes back up.
Common questions#
Are QuantiYard calculators accurate enough to order from?#
For ordering material, yes, which is what they are for. Every one carries a waste allowance and states what it assumes. They are not accurate enough to build structure from: nothing here sizes a beam, a header, a footing or a load path, and anything a building inspector signs off on needs a designer, not a calculator.
Where do the densities, bag yields and coverage rates come from?#
Three places, and every calculator says which. Some are printed on the package, like a bag yield or a spread rate. Some come from a published standard, like the insulation R-values, which are the ENERGY STAR recommended levels from 2021 IECC Table R402.1.3. The rest are industry averages, and where a figure is an average the page says so rather than implying a source it does not have.
Why does a calculator sometimes round down?#
Because rounding up is not always the safe direction. Rebar spacing is a maximum, so rounding a bar count up would put a bar outside the clearance line, and the rebar calculator rounds down. Wallpaper strips per roll round down because a strip two inches short is waste rather than a strip. Everything sold in whole units rounds up.
How current are the prices in the cost guides?#
All eighteen cost and comparison guides carry 2026 US national ranges, set in September 2026, and every one names its date on the page. They are scheduled for a full recheck in January 2027, before the spring project season. A guide's own cost table is the source for any pin or chart quoting the same work, so the two cannot drift apart.