SHEET 01 OF 03 PAINT / INTERIOR SCALE 1:1 REV 2026-08-11

Measure it once.
Buy it once.

Fifteen calculators for home projects. Every constant is read off a manufacturer data sheet, and the formula is printed next to the answer.

OPEN A CALCULATOR
COVERAGE ......... 350 sq ft/gal at 2 coats
SOURCE ........... SW / BM / Valspar overlap
ROUNDING ......... UP, to whole gallons
A plan of the room you entered, dimensioned, with the paint arithmetic below it. 14 ft 12 ft 8 ft PLAN — WALLS ONLY, CEILING EXCLUDED

A = 2(14 + 12) x 8 = 416 sq ft 416 x 2 ÷ 350 = 3 GAL

DRAWN MEASURE & BUY
UNITS FT · SQ FT · GAL
NOTE EXCLUDES OPENINGS
SHEET 02 OF 03 CALCULATOR SCHEDULE 4 GROUPS / 15 ITEMS ALL LIVE

Fifteen calculators, one buying answer each.

Grouped the way a drawing set is, by discipline. Open a group to see its sheets.

Press P L C I to open a group from anywhere on the page.

P Painting & finishing 2 calculators gallons
L Landscaping 7 calculators cu yd, tons, pounds, posts
C Concrete & masonry 2 calculators bags, pavers
I Interior 4 calculators rolls, boxes, sheets, gallons
INDEX 15 OF 15 ISSUED
STATUS FOR CONSTRUCTION
SHEET 03 OF 03 GENERAL NOTES RESOURCE STANDARD 6 ITEMS

Built for answers you can defend.

Six rules every calculator on this site has to pass before it ships. They are the reason the numbers are worth trusting.

  1. Sourced numbersCoverage and yield constants trace to a manufacturer data sheet or an industry reference, cited by name and date.
  2. Triangulated mathEvery calculator is checked against independent calculators before it launches, and disagreements are explained rather than hidden.
  3. Formula shownThe exact arithmetic is printed on the page beside the rounded buying quantity. If we will not show it, we do not ship it.
  4. No fake experienceThe guides cover estimation, not craft technique. No invented jobsite stories, and an honest note wherever a job needs a professional.
  5. Honest commercePaid links only cover what the calculation implies, with anything else in a separate block that says so.
  6. Rounded to what you buyNobody sells 2.09 gallons. Answers come as whole gallons, bags and rolls, with the raw math printed beside them.

READ THE SOURCES PAGE

SPEC RESOURCE STANDARD v1
AUDIT /SOURCES/