Grout Calculator for 12×12 Tile
The tile dimensions are pre-filled to 12×12 inches — the most common floor and wall tile size. Enter your area and joint width to get pounds of grout and bag count instantly.
Tile & Area
Grout Joint
Grout Type & Bag Size
How the grout formula works
Step 1 — joint length per unit area (TCNA/Laticrete geometry)
joint_len_per_area = (tile_L + tile_W) / (tile_L × tile_W) [1/in] Each tile shares half its perimeter with its neighbours, netting (L+W) of joint per tile face area L×W. A 12×12 yields 24/144 = 0.167/in; a 2×2 mosaic yields 4/4 = 1.0/in — 6× more grout for the same area.
Step 2 — grout weight per square foot
lb/sq ft = joint_len_per_area × joint_width × joint_depth × density (lb/in³) × 144 Density: sanded 104 lb/ft³ (= 0.0602 lb/in³), unsanded 90 (= 0.0521), epoxy 110 (= 0.0637). Multiplying by 144 in²/ft² converts the per-in² result to per-ft².
Step 3 — total pounds and bags
grout_lb = lb/sq ft × area × (1 + waste%/100) bags = ⌈ grout_lb / bag_size − 1e−9 ⌉ The −1e−9 float guard prevents a spurious extra bag when the result lands on exactly a whole number due to floating-point rounding.
For 12×12 tile with a 1/4 in sanded joint at 5/16 in depth, you need about 0.113 lb of grout per square foot — one 25 lb bag covers roughly 222 sq ft net. Narrowing the joint to 1/8 in drops consumption to about 0.056 lb/sq ft, so one bag covers over 440 sq ft.
Related tools
Frequently Asked Questions
For 12×12 tile with a 1/4 in joint at 5/16 in depth (sanded grout, 104 lb/ft³): the coverage rate is 0.1128 lb/sq ft. Per 100 sq ft that is 11.3 lb raw, or about 12.4 lb with 10% waste — one 25 lb bag. For 200 sq ft: 24.8 lb with waste, so one 25 lb bag (or two for safety with excess cuts).
12×12 tile is typically laid with a 1/8 in to 3/16 in joint for a contemporary look, or 1/4 in for a traditional look. Joints under 1/8 in need unsanded grout; 1/8 in and wider use sanded grout. The "rectified" vs "pressed" edge of the tile also determines how tight a joint you can hold — rectified tile can use 1/16 in unsanded joints.
At 1/4 in joints (0.1128 lb/sq ft): 25 lb covers about 222 sq ft before waste. At 1/8 in joints (0.0564 lb/sq ft): 25 lb covers about 443 sq ft. Joint width is the dominant variable — narrower joints dramatically increase coverage per bag.
For joints 1/8 in (3 mm) or wider: sanded grout (density ~104 lb/ft³). For joints under 1/8 in: unsanded grout (~90 lb/ft³). Most 12×12 installations use 1/8 to 3/16 in joints — sanded is correct for most 12×12 jobs unless you are going very tight.
This page pre-fills the tile size to 12×12 inches for the most common floor and wall tile size. All the same inputs are available — you can change the area, joint width, joint depth, waste, and bag size. The formula is identical to the main grout calculator because it uses the same shared component.