Score the cut lines with a tile scribe. A tile scribe is a small, sharp hand tool that etches a cut line into the tile. This etching helps make sure the tile snaps where you want it to instead of breaking or cracking elsewhere. The scoring only needs to be 0.125 in (0.32 cm) or so deep.
You can get a tile scribe at any hardware store or online. Use tile nippers to clip away the excess tile. Think of tile nippers as industrial-strength fingernail clippers. Start at the corner of the tile that’s being cut away, and squeeze the handles together to make the top and bottom blades take small “bites” out of the tile. Start “nibbling” more carefully as you approach the scored line.
Standard tile nippers will work with practically every kind of tile, although some natural stone tiles (like slate) may be too fragile. Consult your tile supplier if needed. You can also use specialty tile nippers for glass tiles or other particular types. Be careful not to nip one of your fingers while you work. Wear work gloves to protect your hands from cut tile edges and safety glasses to protect your eyes from snipped shards of tile.
Make sure your cuts are correct by dry-fitting the tiles. Because the toilet base will cover the cut tile edge, your cuts don’t need to be perfect. However, take the time to dry-fit the tiles in place to make sure your cuts are generally accurate—ideally, no more than 0.5 in (1.3 cm) larger than the flange.
Use plastic spacers to account for your grout lines when dry-fitting the tiles. If you’re going to rest a removable toilet flange on top of the installed tiles, remember to remove it before dry-fitting (and later, when laying the tile!). If your dry-fit lines up properly, you’re ready to set these tiles in place in the same way you did the rest of the floor.