How much grout do I need?

THE BASICS

1. What drives grout consumption

Three variables rule: tile size (small tile has far more lineal feet of joint per sq ft), joint width (a 3/16 in joint takes almost double a 1/8 in one), and tile thickness — deeper tiles hold deeper joints.

A 12×12 floor with 1/8 in joints consumes about 6 lb per 100 sq ft; the same floor at 3/16 in rises toward 9-10 lb. Large 24×24 formats drop to roughly 3 lb per 100 sq ft: fewer joints per area.

FIGURES

2. The formula behind the charts

The industry worksheet (metric version of the TCNA table) is pure geometry: joint volume per area = (length + width) ÷ (length × width) × joint width × tile thickness, all in the same units; mass comes from multiplying by grout density (1.6 g/cm³ ≈ 100 lb/ft³) plus about 10% application loss.

You don't have to run it by hand: the grout calculator in our toolbox does it with your exact tile format and joint width, in metric (kg/m²) with easy pound conversion (1 kg ≈ 2.2 lb).

FIGURES

3. Typical figures by tile format

These references assume cement grout with 5/16 in thick tile. Formats differ by up to 2×: never use the same number for mosaic and for 24×24 — run your own case through the calculator.

SHOPPING

4. How many bags to buy

Cement grout ships in 10 and 25 lb bags (plus small repair pails). A 25 lb bag covers about 400 sq ft of 12×12 tile with 1/8 in joints — most rooms take one bag with plenty left for the final wash.

Buy the full bag: opened grout absorbs humidity and won't survive a second session. The bag's coverage chart overrides any rule of thumb, and epoxy grouts are sold as two-part kits measured per area — follow the kit, not pounds.