This page explains how RenoCalcs calculators produce their results, which default values they use, and what they do not cover.
Units and rounding
- All calculations run internally in metric units (meters, square meters, cubic meters, liters) and are converted for display. 1 inch = 2.54 cm and 1 US gallon = 3.785 liters exactly.
- Quantities you buy, such as bags, boxes and cans, are always rounded up to the next whole unit.
- Displayed values are rounded for readability; the underlying calculation is not rounded.
Default values
Some results depend on the product you buy. We start with common published values and let you change them:
- Pre-mixed concrete bag yield: 80 lb ≈ 0.60 cu ft, 60 lb ≈ 0.45 cu ft, 40 lb ≈ 0.30 cu ft
- Paint coverage: 350 sq ft per gallon per coat (the conservative end of the typical 350–400 range)
- Door and window areas for paint: 21 sq ft (3 × 7 ft) and 15 sq ft (3 × 5 ft)
- Flooring waste: 10% for straight layouts, 15% for diagonal or herringbone
Always check the label or data sheet of the product you are buying and adjust the inputs if they differ.
What the calculators do not do
The calculators estimate material quantities. They are not a substitute for structural design, engineering or local building code advice. For load-bearing work, consult a qualified professional.
Privacy
Calculations run in your browser. The measurements you enter are not sent to our server.
Found an error?
If a result looks wrong, please let us know through the contact page so we can check it and correct it.