Six calculators, one room
Finishing a room is not one question, and until now this site answered it
as if it were six. You typed the same length, width and ceiling height
into the drywall calculator, then the compound one, then the screws, then
the paint, then the tile, then the grout — and finished with six tickets
to add up by hand.
This types it once. What comes back is the same six answers, from the
same six calculators, as one list you can take to a merchant.
A 12 × 14 ft room, 8 ft ceiling, boarded and painted:
21 × 4 × 8 ft sheet drywall
2 × 61.7 lb pail joint compound
205 × linear ft joint tape
3 × 1 lb box screws
3 × 1 US gallon wall paint
1 × 1 US gallon ceiling paint
Six lines. One room typed once.
Nothing here is a second opinion
The only arithmetic on this page is geometry: perimeter, wall area,
ceiling area, floor area. Every quantity comes from the calculator that
owns it, called with those areas. If the
drywall calculator changes
its mind about waste, this changes with it, because there is no second
implementation to drift. That is worth more than it sounds — a project
tool that recalculated everything itself would be seven answers, and
seven answers is worse than six.
What it decides for you, and where to argue
Every one of those is a link on the ticket with your room already in it,
so second-guessing a line costs a click rather than a re-measure.
What three rooms come to
Boarded and painted at an 8 ft ceiling with one door and one window, straight from the calculator on this page. The bathroom adds a tiled floor in 12 × 12 in tile.
The rest of the job
A room is rarely the whole job. The
square footage calculator
handles a floor that is not a plain rectangle and hands the area to any of
these, the
drywall screw calculator
breaks the fastener count down by schedule, and the
crown molding calculator
covers the trim this list does not. Boarding a ceiling below an unfinished
loft? The board and batten calculator
handles a feature wall in the same room.
Common questions
What does this work out that the individual calculators do not?
Nothing. That is the point. Every line comes from the calculator that already owns it — the drywall calculator does the board, the paint calculator does the paint, the grout calculator does the grout — called with the areas this page derives from your room. There is no second set of arithmetic here to fall out of step with the first. What it saves you is typing the same room into six forms and then adding six tickets together.
Why is the board quoted in 4 by 8 sheets when longer ones exist?
Because a shopping list has to commit to something. The drywall calculator offers 4 by 8, 4 by 10 and 4 by 12 and lets you weigh fewer joints against a sheet you can actually carry; that is a real decision and it is not one this page should make silently for you. It commits to the four-by-eight — the size every merchant stocks and the only one that fits in a car — says so on the ticket, and links straight to the page that prices the other two with your room already in it.
Why do the doors and windows come off the paint but not the board?
Because the trades genuinely disagree, and each is right about its own work. You do not paint a doorway, so openings come out of the paint at the published deductions. Plenty of hangers sheet straight over an opening and cut it back afterwards, which is faster and wastes board on purpose — so the board order does not deduct, which is also the safe direction. Deducting would order less board than someone working that way actually uses. The drywall calculator will deduct if you tell it to.
Why is the total not just everything added up and rounded once?
Because you do not buy it in one transaction. Paint comes in tins, board in sheets, compound in pails, and each of those rounds up on its own — you cannot buy nine tenths of a pail. Summing the raw quantities and rounding once at the end would give a smaller number and a wrong one. Every line here rounds up in its own units, exactly as its own calculator does.
Some lines have no price. Is the total still right?
It is right about the lines it covers and it says how many that is. A total printed over a partly priced list is the most misleading thing this page could show, because a blank line is invisible in a sum — so the ticket reads "seven of eight lines priced" rather than presenting a short figure as the cost of the room. Joint tape is always unpriced, because the constants file has no published roll length and this site does not invent one.
Can I use it for a room with a sloped or vaulted ceiling?
No, and it says so rather than quietly under-ordering. Everything here runs off one ceiling height, which is right for most rooms and wrong for the interesting ones. A vaulted ceiling, a stepped soffit or a room open to a stairwell is its own calculation — measure the wall areas yourself and take them to the individual calculators, which accept an area directly.
Does it cover flooring other than tile?
Not yet. The floor question is tile or nothing, because tile and grout are the two the site has published charts for and both key off the same floor area. Laminate, vinyl and carpet each come with their own waste conventions and pack sizes, and adding them without the constants to back them would be guessing.
Sources
Coverage is a published range and the default is the value BEHR quotes. Primer carries its own range because it is a different product, but not for the reason commonly repeated: two KILZ data sheets, including the PVA primer formulated specifically for bare uncoated drywall, both publish 300 to 400 sq ft per gallon. That is the same territory as finish paint, not a third less. No typical value is published for primer, so none is stored; calculators take the thirsty end of the range, because a wall you run out of primer on halfway is a wall with a visible line. Door and window deduction areas are BEHR's stated averages and are used by the drywall calculator too, since a door is the same hole whichever trade is working round it.
- Default waste allowance
- 10%
- SOURCE REQUIRED — tile cutting waste by lay pattern. These are trade estimating conventions rather than published constants, and no manufacturer or standards body publishes them. Every one is exposed as a waste percentage the user can overwrite
Awaiting verification against the published data sheet
Waste depends on lay pattern: straight 10%, diagonal or offset 15%, herringbone or complex 20%. Flooring planks use 10%.
- Default waste allowance
- 10%
- Gold Bond Gypsum Board product page (National Gypsum) — panel width 48 in
- Lowe's Drywall Materials Estimator — sheet lengths and per-sheet consumable rates
- USG Sheetrock UltraLightweight All Purpose Joint Compound submittal sheet J2051 — coverage approximately 9 to 10 gallons per 1,000 sq ft of gypsum panels, packaged in 4.5 gal pails, 3.5 gal cartons and 4.5 gal cartons, up to 40 percent lighter than conventional
- USG Sheetrock Brand All Purpose Joint Compound submittal sheet — coverage approximately 125 to 150 lb per 1,000 sq ft of gypsum panels, packaged in 48 lb, 50 lb and 61.7 lb pails and cartons, varying by geographic region
- Grip-Rite coarse thread drywall screws, published SKU table — 1 lb, 5 lb and 25 lb containers; piece counts give 313 per lb at 1 in, 258 at 1-1/4 in, 200 at 1-5/8 in and 175 at 2 in
The 10% allowance is the 1.10 multiplier given in the drywall formula. Screw, tape and compound rates are trade estimating conventions rather than physical constants: they vary with sheet size, framing spacing, finish level and waste, and are always presented as approximate. Fastener spacing is governed by local code and the manufacturer's schedule. Screw counts are ranges because spacing within a schedule is not fixed, and joint compound is split by product type because the two differ by roughly 2x — a lightweight compound covering the same board at about 72 lb per 1,000 ft2 against 123 to 140 for conventional all-purpose. The lightweight figure is now verified against USG's own submittal sheet, and it was wrong: USG publishes 9 to 10 gallons per 1,000 sq ft, which at 4.5 gal and 36 lb per pail is 72 to 80 lb — not the flat 72 stored here, which was the bottom of the band quoted as if it were the whole of it. Coverage is published in gallons rather than pounds, so the gallon figures are stored alongside and are the ones to trust.
- Default waste allowance
- 0%
A published chart, not a derived formula. Grout quantity depends on the total linear footage of joint, which is a function of tile size, joint width and tile thickness together — the implementation plan explicitly forbids deriving it and requires a manufacturer chart. The thickness is not a free variable here: it is fixed per row by the chart, 1/4 in for tiles up to 6 in and 3/8 in above, and changing it would invalidate the figure. Sizes and joint widths are therefore offered as a choice from the chart rather than as free numbers, which is how the manufacturer intends it to be read. Other grout products differ; check the box.
Unit conversions are exact by definition and need no source.
How we choose and cite these figures
