How to Choose a Grout Pen

Grout pens look interchangeable on a store shelf, but the wrong pick shows up fast: a 5mm tip wandering over 2mm lines, a bright white that fights your aged tile, or a bargain pen that washes out after two mop cycles. This guide covers the four decisions that matter, in the order you should make them.

1. Match the tip to your grout line width

Measure a grout line before you buy anything. Most wall tile sits on 2 to 3mm joints, floor tile commonly runs 5 to 10mm, and older installations can be wider still. The tip should be the same width as the joint or slightly narrower.

• Narrow tips (2 to 4mm): subway tile, mosaic sheets, and most bathroom walls. A narrow tip on a wide line means two or three passes, which is slow but workable.
• Standard tips (4 to 6mm): the all-rounder for typical floors and kitchen backsplashes.
• Wide or chisel tips (8 to 15mm): large-format floor tile and commercial-style joints. A wide tip on a narrow line will paint your tile edges, so keep painter's tape handy if you go this route.

2. Pick the formula for the room

Almost every pen is either water-based acrylic or a solvent-carried epoxy hybrid. Water-based pens are low odor, easy to clean up, and fine for most dry and lightly damp areas. For shower floors, steam-heavy bathrooms, or anything that gets scrubbed weekly, look for pens marketed as waterproof or epoxy-fortified and check that the label mentions mold and mildew inhibitors. Our steam cleaning durability article covers how the two formulas hold up under heat and moisture.

3. Choose a color you have tested, not guessed

Brilliant white is the top seller and also the most common regret. Against cream or bone tile, stark white grout can make the tile itself look dingy. If your tile is anything other than pure white, test a short hidden run first, or step down to an off-white or light grey. Charcoal and black pens are excellent for hiding stains on dark floors and for adding contrast to plain white subway tile. The full decision process is in our color selection guide.

4. Buy enough pens the first time

A standard pen covers roughly 100 to 150 linear feet of grout in one coat. A small backsplash may need one pen; a 100 square foot floor with 12 inch tiles has around 200 linear feet of joints and will need two or three, more if you change color and need a second coat. Skip the math and use our grout pen calculator, which estimates linear footage from your room size and tile dimensions.

Quick brand notes

Rainbow Chalk (UK) and Grout-Aide (US) are the two names you will see most, and both make reliable standard-tip pens. Rejuvenate sells a widely stocked white restorer marker, and Mapei's Grout Refresh is a brush-on colorant worth considering when a whole floor needs recoloring rather than touch-ups. Whichever brand you choose, buy one pen first and test a corner before ordering the full batch.

When a pen is the wrong tool

A grout pen recolors the surface. It will not rebuild crumbling joints, fix cracks that keep returning, or stop water getting behind tile. If your grout is structurally failing, read our regrouting cost guide and consider a professional; our tile contractor directory lists tile and grout specialists in every state. Not sure which side of the line you are on? Take the two-minute refresh or regrout quiz.