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Tile Grout Coverage: How Much Grout Per 100 Sq Ft?
The formula
Area × joint factor = grout weight. Rule of thumb: 100 sq ft of 12×12 tile with 1/8 inch joints needs one 25-lb bag of sanded grout. Small mosaics (2×2) need roughly double; large 24×24 with tight joints need half. Wider joints and deeper beds scale linearly.
Worked example: 10×10 ft bathroom floor
100 sq ft, 12×12 tile, 1/8 joints → 1 bag (25 lbs). Same floor in 2×2 mosaic → 2 bags. Same floor in 24×24 with 1/16 joints → half bag — buy one full bag anyway since partial bags cannot be reordered by dye lot.
Sanded vs unsanded vs epoxy
- Sanded: joints 1/8–1/2 inch, floors, strongest for wide gaps
- Unsanded: under 1/8 inch, walls, smoother finish
- Epoxy: stain-proof and chemical-proof, 3× price, short working time
- Pre-mixed urethane: no mixing, great for DIY backsplashes
Steps that prevent callbacks
Mix to peanut-butter consistency, slake 10 minutes, remix — skipping slake weakens grout. Float diagonally, sponge lightly with minimal water (over-washing weakens joints and causes efflorescence), then haze-buff next day. Seal cement grout after 72 hours.
FAQ
- Seal necessary? Yes for cement grout, yearly in showers; epoxy and urethane never need sealing.
- Cracked grout? Movement or over-washed joints — rake out 2/3 depth and regrout that section.
- Color change? Grout stains exist but never match perfectly; test a hidden spot first.
Cost reality
One 25-lb bag costs $15–$25, sealer $12, float and sponges $20 — a typical bathroom regrout totals under $60 DIY versus $300–$600 pro. Epoxy doubles material cost but halves future maintenance in a rental shower.
Limits
Estimates assume standard 1/4 inch bed depth; thick-bed or uneven substrates drink more. Never grout over movement joints — use color-matched silicone there or cracks return within months. Plan tiles with our tile estimator.
Maintenance calendar
Squeegee shower walls after use — 30 seconds prevents 90% of mildew. Reseal cement grout yearly in wet areas; dry areas every 2–3 years. Re-caulk tub-to-tile joints (never grout there) at the first hairline crack. Bleach pens whiten surface stains but never fix structural cracking underneath.
One last rule: save half a bag of grout plus the sealer bottle with the room name written on both. Touch-ups from the same batch blend invisibly; a new bag two years later never matches, and that leftover half-bag costs less than one hour of rework.