ExactMaterials is built and maintained by Liviu Iulian Taune. It is a set of material calculators and guides that show their working: what you measured, what was assumed, and where each assumption comes from.
Why this site exists
I’m a front-end developer, not a contractor. Estimating material is, underneath, arithmetic — area, coverage rate, waste allowance, pack size — and an estimate is only as good as the assumptions inside it, so this site puts them where you can read them.
Every calculator does that in the same places. Under the tool, a short list states what the maths assumes. In the results, some lines carry their assumption with them: in the flooring and tile calculators the waste line says whether its percentage came from the site’s table, the plan the calculator drew or a figure you typed, and in the drywall calculator the screw line gives the spacing it counted. Further down each calculator page, a sources section either links the published document a number came from or says plainly that the number is this site’s own.
What I can’t give you is a tradesperson’s judgement about your particular room. I have never installed a shower, hung drywall or set tile on a job, and nothing on this site should read as if I had. If a number here disagrees with your supplier’s spec sheet, the spec sheet wins — and I’d like to hear about it, because that is a bug.
How the results are calculated
The arithmetic runs in your browser. There is no server doing the sums, no account and no saved project. Your room’s dimensions and your prices are not sent anywhere. The site’s analytics records how the calculators are used — which one, the pattern and the units, how often a result is recalculated, the number of pieces in a plan you print, and the waste percentage if you type your own in place of the site’s — but not those measurements or prices, and the privacy policy lists every event and what it records. The calculator keeps your last inputs in your browser’s local storage so they are there next time, and writes them into the page address after the # sign, which is how a copied link brings an estimate back. That part of an address is not sent to the server.
The engine works in inches internally and converts at the edges. The eight flooring and tile calculators share a layout engine that places pieces by pattern — grid, half and third brick offsets, vertical stack, diagonal, herringbone, chevron, basketweave and a random plank stagger — then clips each piece against the room outline to decide whether it is a full piece or a cut. The plan is drawn to scale up to 4,000 pieces; past that the drawing is simplified and the waste falls back to the table figure for the pattern.
Offcuts are used again before a new piece is opened. In every pattern except the plank stagger, a cut that leaves at least a quarter of a piece goes onto a scrap pile, and the smallest offcut that covers a later cut is taken from it; anything smaller is counted as waste. In the plank stagger, every row after the first starts with a cut piece no shorter than the minimum stagger — 6 inches, or a quarter of the plank once the plank is longer than 24 inches — and offcuts at least that long go back on the pile to start or finish later rows.
Inputs are checked against fixed ranges, and nothing is calculated while a field is out of range. Purchase quantities always round up, because boxes, bags and sticks are not sold in fractions. Areas are shown to one decimal, money to two, percentages to one.
Where the waste figures come from
The waste allowances are this site’s own table, not a figure from a published standard: 10% for a grid, a half offset, a vertical stack or a plank stagger; 12% for a third offset or basketweave; 15% on the diagonal; 17% for herringbone; 19% for chevron. On top of the pattern figure the calculator adds 2 points for an L-shaped room and 3 each for a floor under 40 square feet, a piece 24 inches or longer and a first install, and it caps the total at 25%.
The table climbs with the pattern because the cutting does. Laid square to the walls, a grid only cuts the pieces along the edges of the room; turned 45 degrees, every piece that meets a wall is cut, which is the note the calculator shows beside the diagonal option, and herringbone and chevron are laid at an angle to the walls as well. The calculator also measures the waste in the plan it drew for your room and uses whichever figure is higher, and the waste line in the results says which one it used. Type in your own percentage and it uses yours as given.
Which sources back which calculator
Each calculator page lists its sources with links, and says which of its numbers are the site’s own. This is the short version.
| Calculator | Published sources it cites | This site’s own figures |
|---|---|---|
| Flooring Calculator | None, and the page says so. | The waste table and the points added to it, the 25% cap, the stair allowances and the default prices. |
| Vinyl Plank (LVP) Calculator | COREtec’s installation guidelines for WPC products with 5G fold: end-joint stagger, the row-starting piece, the perimeter gap, acclimation. | The waste table, the wear-layer suggestions, the underlayment overlap and the default price. |
| Laminate Flooring Calculator | Shaw’s Repel installation and care guides (expansion gap, end-joint stagger, water resistance); EN 13329 for the AC classes; ASTM E989 and IBC 2021 section 1206.3 for impact sound between dwellings. | Which AC class suits which room, the underlayment overlap, the waste table and the default price. |
| Hardwood Floor Calculator | NWFA guidance on moisture content and acclimation, as published in Hardwood Floors magazine. | The waste table, the extra for random-length bundles, the racking advice, the share of short boards and every cost figure. |
| Tile Calculator | ANSI A108.02 section 4.3.8.2 on offsets, as quoted by the Ceramic Tile Education Foundation; LATICRETE’s 253 Gold data sheet for thinset coverage; Custom Building Products’ coverage charts for its Polyblend Plus grouts. | The waste table and the points added to it and the default prices. |
| Subway Tile Calculator | ANSI A108.02 sections 4.3.8.1 and 4.3.8.2 on offsets and joint width, as quoted by the Ceramic Tile Education Foundation; LATICRETE’s 253 Gold data sheet; Custom Building Products’ grout coverage charts. | The waste figures by offset, the spacer count, the joint advice for handmade tile and the default prices. |
| Herringbone Tile Calculator | LATICRETE’s 253 Gold data sheet, for thinset coverage and back-buttering; Custom Building Products’ grout coverage charts. | The 17% table figure, the 20% for small rooms and the blade, clip and labour costs. |
| Backsplash Calculator | ANSI A108.02 section 4.3.8.2, as quoted by the Ceramic Tile Education Foundation; LATICRETE’s 253 Gold data sheet; Custom Building Products’ grout coverage charts. | The 18 inch default height, the extra cuts per outlet, the 15% for mosaic sheets, the edge-trim prices and the waste table. |
| Paint Calculator | Sherwin-Williams’ stated coverage of 350 to 400 square feet a gallon. | The adjustments for new drywall, texture, spraying and roller nap, the door and window allowances and the trim figure. |
| Exterior Paint Calculator | Sherwin-Williams’ stated coverage of 350 to 400 square feet a gallon, used for smooth siding. | The coverage for vinyl, stucco, rough wood and masonry, the gable height taken as a share of its width, the dormer and trim allowances, the storey heights and the prep and caulk estimates. |
| Drywall Calculator | GA-216-2010 section 5.4 and Table 1, for screw spacing and which ceiling board each framing spacing allows; IRC 2021 Table R302.6, for the board between a garage and the rooms above it. | The 10% waste, the screw spacing and the framing the screw count assumes, the screws per pound, and the compound and tape per square foot. |
| Baseboard Calculator | None, and the page says so. | The 10% mitre allowance, the extra for awkward rooms, the default doorway width and the stock lengths offered. |
Two of the twelve cite nothing, and their pages say so. Not every standard is posted in full, either. Where one is not, the page links a published summary of it instead: a trade foundation quoting it, an association’s magazine, a standards body’s catalogue entry.
What the site does not do
It does not measure your room. A result is only as good as the numbers typed into it, and beyond checking that each one is in a sensible range, the calculator cannot tell a wrong measurement from a right one.
It does not know your floor or your walls. Whether a slab is flat enough for large tile, how much moisture is in a subfloor, whether a wall is straight: none of that is an input, and all of it is for whoever looks at the job in person.
It does not know what labour costs. The optional labour line multiplies the area, or the length for trim, by the rate in its box; the default rate is one of the site’s default prices, not a figure for where you live.
It does not know what your merchant sells, or in what boxes. The coverage per box in the flooring and tile forms is a starting figure, and the carton on the shelf may cover more or less: read its label and type that figure in. The same goes for sheet sizes and trim lengths. The forms offer a few, and your store may stock others.
It is not a quote. A merchant’s quote is a price for specific product on a specific day; a result here is arithmetic on the numbers in the form, and the prices in it are this site’s defaults until you type in your own.
How to read a result
Take a tile floor. The result lists the area to cover; the waste allowance, with the reason for it; the material to order, which is the area plus that allowance; and the boxes, which are the material to order divided by the coverage per box in the form, rounded up. The plan line underneath says how many full and cut pieces the drawing used, so you can see where the waste comes from.
So the margin in an order has two layers. The waste allowance covers what the layout consumes in cuts; rounding up to whole boxes adds whatever is left over in the last box. Neither is a spare for future repairs. If you want spare tiles or planks put away for later, add them yourself: the calculator does not.
How the figures were built
Every result comes out of one calculation engine, a single module that all twelve calculators call. The plan drawings in the guides, and the numbers in their captions, come from that same engine when the site is built. Where a page quotes a figure that a calculator also works out — a box count, a waste allowance, a pound of grout — the page takes it from the same functions as the result, and a test checks each of those figures against the calculator.
Where a calculator uses a manufacturer’s number, its page names the source. Paint starts at 350 square feet per gallon, the low end of the 350 to 400 Sherwin-Williams states. Thinset uses 95 square feet per 50 lb bag, the top of the 80 to 95 in LATICRETE’s data sheet for 253 Gold. Grout follows the coverage charts Custom Building Products publishes for its Polyblend Plus grouts, to within about 1%. The primer line on the two paint calculators is the exception, and their pages say so: it uses the paint figure, not the 200 to 300 square feet a gallon Sherwin-Williams gives for primer.
Where the prices come from
They are default values, not a price survey: this site’s estimates for mid-range product in the US, there so that a calculator shows a total before you have typed anything of your own.
The number that matters is the one on your receipt. Every price field in every calculator is editable. Put in what your merchant quoted and every total on the page follows it; leave the defaults in and treat the money as a rough order of magnitude. The quantities — square footage, boxes, waste, cuts and the plan drawing — do not depend on the prices at all.
The defaults were last set on 2026-09-13, and they get another look every three months. If that date is more than four months old, the review is overdue.
What it costs to use
Nothing: using the site is free, and there is no paywall. It does not sell anything either. There are no affiliate links, no sponsored products and no lead-generation forms selling your project to contractors, and no one pays for placement in the content. If a paid arrangement ever exists, it will be labelled on the page where it appears.
Corrections
If a number here is wrong, tell me: write to hello@exactmaterials.com. The contact page says what to include and how long a reply takes, and the person who answers is the one who builds the site.
A correction that comes with a source — a data sheet, an installation sheet, a label — is the quickest to check. When a fix goes in, the page’s “Updated” date moves with it. That date is not typed by hand: it is read from the site’s change history for that page when the site is built.