Ordering bathroom tile comes down to one number, and most people guess it. This is Badeloft’s working guide to getting that number right: the calculator below does the math for every surface in the room, and the rest of the page shows where each figure comes from.
Every waste percentage, coverage rate, and cost range here is drawn from published manufacturer guidance and installer convention: Fireclay Tile’s overage recommendations, Schluter’s mortar coverage charts, and the Tile Council of North America’s grout rules, checked against what working tile setters actually order.
When we say bathroom tile, we mean both the simple case and the complicated one: a single floor, and a full room where the floor, the shower walls, and the tub surround each get tiled, each with its own measurements and its own openings to subtract.
If this is your first tile order, the fear is real: order short and the reorder may not match; order long and you paid for boxes you never open. If you’re mid-remodel and a contractor just handed you a quantity, you want to check it before the invoice clears. And if you have your heart set on herringbone, you already suspect the pattern changes the math. It does.
By the end you’ll have five numbers you can defend: square footage per surface, the right waste percentage for your pattern, tiles, boxes, and a realistic materials budget. The page runs in five parts: the calculator, the math behind it, measuring the room, patterns and waste, and ordering, materials, and cost. Start by running your own numbers below; everything after explains them.
Optional: estimate material cost
Your takeoff
How the Tile Math Works, Step by Step
Four steps take you from a tape measure to a purchase order:
- Measure each surface in feet and multiply length by width to get square feet.
- Add the surfaces together, then subtract large openings such as doors and windows.
- Multiply by your waste factor: 1.10 for a straight lay, more for angled patterns.
- Divide by the coverage printed on the tile box and round up to whole boxes.
Here is the worked example the calculator loads by default. A 5 by 8 foot bathroom floor, a classic American full-bath footprint and the same one our 5 by 8 bathroom remodel cost guide budgets around, measures 40 square feet. With 12 by 24 inch tile laid straight, add 10 percent: order 44 square feet. Each tile covers 2 square feet, so plan on 22 tiles. If a box covers 16 square feet, 44 divided by 16 is 2.75, which rounds up to 3 boxes.
One deliberate simplification: the count ignores grout joints. Joints make each tile occupy slightly more area, so ignoring them overstates the tile you need by a hair. When you’re deciding between running short and having a spare, that is the right direction to err.
How to Measure a Bathroom for Tile
Installers do not measure a bathroom as one rectangle, and neither should you. Build what we call the whole-bathroom takeoff: list every surface that gets tile, measure each one separately, subtract its openings, then add them up. The calculator above is built around that list.
Floors. Measure at the longest and widest points, wall to wall under the vanity’s toe kick. An L-shaped floor splits into two rectangles; measure each and add them.
Walls and showers. Measure each wall separately, width times height to the line where tile stops. Most installers advise against deducting the shower door opening; the surplus becomes your cut cushion. Subtract genuine openings like a window. If the design includes a storage niche, prefabricated boxes commonly come in sizes like 12 by 12, 12 by 16, and 12 by 24 inches, about 3.5 inches deep; browse prefabricated shower niches to lock the size before you order tile, then add the niche’s back and side faces to the wall total.
Tub surrounds. A standard alcove tub runs 60 inches long and 30 to 32 inches wide, so a surround is three walls: one back wall at 60 inches wide and two end walls at the tub’s depth, each measured from the tub rim up to where the tile stops, commonly 60 inches above the rim or the ceiling.
Picture a homeowner tiling around that standard 60 inch tub, floor to a line 60 inches above the rim. The back wall is 60 by 60 inches, 25 square feet. Each end wall is 30 by 60 inches, 12.5 square feet. That totals 50 square feet; subtract a 2 by 3 foot window on the back wall and the net is 44. At 10 percent waste, the order is 49 square feet. Five minutes with a tape measure, and the number is defensible at the tile counter.
Scope changes the takeoff. If you’re only refreshing the floor, one surface line does it, and you can skip everything about surrounds. If the shower and tub walls are in scope, measure them first: walls usually double or triple the order, so they, not the floor, set the budget.
Two last line items. Trim pieces such as bullnose and accent strips sell by the linear foot, not the square foot, so measure exposed edges separately. And one layout decision removes a surface entirely: a freestanding tub needs no tiled surround, and whether a freestanding tub needs tile at all is its own question.
Tile Sizes and Patterns That Fit a Bathroom
Size guidance that holds for most bathrooms: 12 by 24 inch tile is the modern default for floors and walls, small mosaics belong on shower floors, and anything 15 inches or longer per side counts as large format with its own handling rules. Mosaic sheets earn their place in the shower because the sheets follow the floor’s slope to the drain and the extra grout joints add grip underfoot.
Pattern is a style call first; our guide to 2026 bathroom tile trends covers what holds up and what will date the room. But every pattern is also a math call, because the layout sets the waste factor, which the next section prices out.
Tile size forks on the room. If your bathroom is under about 40 square feet, or chopped up by a vanity, a toilet flange, and an alcove, large-format tile means nearly every perimeter piece gets cut, so waste and the required substrate flatness both climb; a 12 by 24 or smaller keeps cuts manageable. If you have an open 10 by 10 floor, large format shines: fewer joints, faster coverage, a calmer surface.
Say you fall for a 24 by 48 porcelain slab look for a 5 by 8 bath. Each tile covers 8 square feet, so the whole floor is only six uncut tiles, and not one of them fits uncut: every piece meets a wall or the flange. Waste runs closer to 20 percent than 10, one miscut costs a quarter of a box, and the substrate has to be dead flat. The slab look is gorgeous; it is simply a large-room format.
How Much Extra Tile to Order for Each Pattern
The direct answer, by layout:
| Layout | Extra to order | Why |
|---|---|---|
| Straight or stacked | 10% | Perimeter cuts only |
| Running bond offset | 10–15% | Offset rows add cut starts at every course |
| Diagonal at 45 degrees | 15% | Every edge tile gets an angled cut |
| Herringbone | 15–20% | Angled cuts at both ends of the run |
| Cut-heavy or mosaic-heavy rooms | can climb toward 25–30% | Obstacles multiply partial tiles |
Handmade-tile makers set the bar even higher for their own material: Fireclay Tile recommends 15 percent extra on field tile and 20 percent on specialty patterns, and their reasoning is the part worth internalizing: an add-on order is a new production run, and a new run may not match your original color exactly.
That dye-lot risk is the real argument for ordering the full percentage up front. Reorders ship from different runs, small add-on orders can carry fees, Fireclay’s is $100 under 25 square feet, and a half-shade mismatch in the middle of a wall reads as a mistake forever. Pros also keep 3 to 5 spare tiles per room after the job for future repairs; build that into the order, not the reorder.
The 10 percent question splits households. In one Houzz thread, a vendor suggested 10 percent extra on a marble foyer and the buyer’s husband called it excessive. For a straight lay, 10 percent is standard advice, not padding. The number only climbs when the pattern angles.
Picture a renovator setting a 3 by 12 herringbone floor in a 40 square foot bath. Ordering at 10 percent, she has 44 square feet on hand; the 45 degree cuts at every wall eat through offcuts that a straight lay would reuse, and she runs out with one corner bare. The add-on order takes two weeks and arrives half a shade warmer. At 20 percent, 48 square feet, she finishes the floor from one dye lot and shelves the spares. The difference was one box ordered on the right day.
Boxes, Dye Lots, and Ordering With a Margin
Tile sells by the box, and boxes commonly cover roughly 8 to 16 square feet depending on tile size, so the box, not the tile, is your real unit of purchase. The ordering sequence:
- Take your waste-adjusted square footage from the calculator above.
- Divide by the coverage printed on your box and round up to a whole box.
- On delivery, check that every box shows the same shade or lot number before installation day.
- Keep 3 to 5 whole tiles after the job; label the box with the room and lot number.
Do this and the outcome is immediate: you walk into the tile shop with a number you can defend, and you never make the mid-project second order that arrives a shade off.
Grout and Thinset: How Many Bags
Tile math that stops at tile leaves two line items unpriced. For thinset, plan around one 50 pound bag per 40 to 50 square feet with the 1/4 by 3/8 inch notch trowel most bathroom tile calls for, per Schluter’s coverage guidance; the deeper notches used for large-format tile drop coverage toward 30 to 40 square feet, and manufacturer charts differ, Custom Building Products’ runs higher per notch, so treat the bag’s own chart as final. Tiles with any side 15 inches or longer may also need back-troweling, a skim coat on the tile’s back, to reach required mortar coverage; installers’ rule of thumb is to budget 15 to 20 percent more thinset when they do.
Grout type is a rule, not a preference: the Tile Council of North America assigns unsanded grout to joints under 1/8 inch and sanded grout to 1/8 inch and wider. Quantity is where guessing goes wrong: consumption is driven by joint length, so a wall of penny mosaic drinks grout while a floor of 12 by 24 with tight joints barely sips it. The chart on the grout bag is the authority; the planner below tells you which end of it you’re on.
Your materials plan
What Bathroom Tile Costs in 2026
Material first, per square foot: ceramic runs about $1 to $5, designer lines higher; porcelain $3 to $10; natural stone $3 to $30, per HomeGuide's 2026 cost data. Installed, with labor, a typical bathroom lands between $7 and $25 per square foot, and porcelain or stone jobs can reach $35 to $50. Labor alone adds roughly $4 to $12 per square foot depending on tile size, pattern, and region, and pattern work is priced like the skill it is: herringbone commonly adds 30 to 50 percent to installation labor over a straight lay.
Run the numbers on the default example: 44 square feet of mid-range porcelain at $4 is $176 in tile, one bag of thinset, one of grout, and the materials side of a floor refresh stays under $250. The labor line is where the budget forks.
If it's a straight-laid floor and you have set tile before, doing it yourself saves that $4 to $12 per square foot, about $180 to $530 on our 44 square foot example, and a weekend. If the job is a herringbone shower with a niche and a glass door, hire it out: the pattern premium exists because angled layouts punish inexperience, and a redo costs more than the pro did. Either way, price the tile against the whole project with our average cost to remodel a bathroom guide so the tile line sits in context.
The longer payoff is the one you feel every morning: a floor and walls you measured yourself, finished from a single dye lot, with spare tiles labeled on a shelf instead of a mismatch staring back from the middle of the room.
Bathroom Tile Questions, Answered
How many 12 by 12 tiles do I need for 100 square feet?
A 12 by 12 tile covers exactly 1 square foot, so 100 square feet needs 100 tiles plus waste: 110 tiles at a straight lay's 10 percent.
How do I calculate tile for a shower?
Treat each wall as its own rectangle, width times height, and add the curb and any niche faces. Most installers keep the door opening in the count as cut cushion. Mosaic floors are figured by the sheet, using the sheet's coverage.
What if my bathroom is not a simple rectangle?
Split it into rectangles, calculate each, and add them. The calculator above handles this directly: enter each rectangle as its own surface.
Can I tile over existing tile?
Sometimes, if the existing bed is flat, sound, and well bonded, though it raises the floor height and is usually the wrong call in wet areas. Our guide to retiling a bathroom wall walks through when tear-out is worth it.
How do I convert square meters to square feet?
Multiply by 10.764. A 4 square meter bathroom floor is about 43 square feet; add your waste percentage after converting.
Plan the Rest of the Bathroom with Badeloft
Tile sets the envelope; the fixtures make the room. Badeloft builds stone resin tubs and sinks for exactly this stage of a remodel, when the takeoff is done and the design decisions start, and a freestanding piece can even take a tiled surround off your list entirely. When the floor plan is settled, browse our freestanding bathtubs to see what anchors the room.