The LATICRETE lineup, and which chart applies
LATICRETE splits its grout range four ways, and each branch has its own coverage table. The cement side is PERMACOLOR Select and PERMACOLOR Grout, sanded, sharing a chart with the older 1500 Sanded Grout. Beside it sits PERMACOLOR Select NS — the unsanded version for polished marble and soft glass — and 1600 Unsanded for joints of 1/8″ and under. The epoxy side is SPECTRALOCK PRO Premium. They do not share numbers: at 12″ tile with a 1/8″ joint, a 25 lb unit of PERMACOLOR Select goes about 383 sq ft while a full unit of SPECTRALOCK goes about 159.
That gap is not a quality difference, it is a packaging one — a full SPECTRALOCK unit is 0.8 US gal of mixed epoxy, and 25 lb of cement grout makes a lot more joint volume than that. It is exactly why comparing brands or lines by bag weight tells you nothing useful, and why this tool keeps a separate published table per product instead of one blended rate.
PERMACOLOR Select is a base, not a finished grout
The bag on the shelf is PERMACOLOR Select Grout Base. It is mixed with water and one pigment packet from a separate PERMACOLOR Select Color Kit — that is how one base supports dozens of colors. For estimating this changes nothing about the coverage number, but it changes your shopping list: counting bags of base and forgetting the color kits is the most common way a LATICRETE order comes up short of usable grout.
It also explains the two charts. LATICRETE publishes coverage for the 25 lb unit and, separately, for a 10 lb base bag. Both presets are here. The 25 lb chart puts 1×1 mosaic at a 1/8″ joint at 51 sq ft; the 10 lb chart says 21. Read the wrong one and your order is off by a factor of about two and a half in the direction that leaves you standing in a half-grouted bathroom.
Where these numbers come from
SPECTRALOCK is the interesting one. Its product data sheet, DS-681, gives packaging and working time but no coverage table — it says to refer to the chart on Data Sheet 254.3. Plenty of calculators stop there and fit a density curve instead. DS 254.3 is a real document: the LATICRETE Grout and Sealant Color Card, and it carries the full table, stated per full unit. Pairing the two — the chart from the card, the unit volume from DS-681 — gives a sourced number with nothing invented in between.
When your tile size and joint width land exactly on a published cell, the calculator uses that cell and says so. When they fall between cells, it fits the standard joint-volume formula to that product's own chart and warns you that it is interpolating. Outside a calibrated zone — roughly faces under 3 inches, or joints over 3/8″ — it stops rather than extrapolating, because that is where published charts and geometry diverge most.
What is deliberately missing
LATICRETE READY-TO-USE Grout is on the same coverage card and is not a preset here. Its table gives only three tile sizes, which is too thin to fit a reliable curve to — the fallback lands around 7% off between the published cells, against a 3% bar for every other product in this tool. The chart cells themselves are fine; the gaps between them are not. A preset that is wrong where you cannot see it is worse than an honest omission.
SPECTRALOCK 2000 IG is also on the card but carries no table at all — LATICRETE points to its estimator instead. Same rule applies: no table, no preset.