Every calculator on Delimetra is built to the same rules, so a result can be traced from the input to the formula and to the document behind it.
Units
Calculations run in SI units inside: metres, kilograms, pascals. Feet, inches and fractions are converted only at the edge — when you type a dimension and when the result is shown. The conversion factors are exact by definition: 1 inch is 25.4 mm, 1 foot 0.3048 m, 1 pound 0.45359237 kg, 1 US gallon 231 cubic inches. Lengths in the US market are rounded to the nearest ⅛ inch for display only; the calculation keeps the full value.
Markets
The page loads with the US market: feet and inches, dollars, US codes. If your browser says you are in the UK, Canada, Australia or another market the calculator offers, it switches after the page has loaded and tells you. A market you choose yourself in the header is remembered and wins over the automatic choice. You can switch only the units with the Imperial / Metric toggle.
Codes and standards
Where a code sets a limit, the calculator checks it and names the section. We currently use:
- International Residential Code (IRC) 2021: concrete strength (Table R402.2), slab thickness (R506.1), stairs (R311.7.5), roof coverings (Chapter 9, R905).
- ASCE/SEI 7-22 for snow loads, IECC 2021 for insulation, NFPA 70 (NEC) 2023 for wire sizing — in the calculators that need them.
- ASTM product standards for sizes: reinforcing bars (A615), masonry units (C90, C216), wire gauges (B258).
Your local code may differ: many jurisdictions adopt an older edition or add amendments. The calculator tells you which edition it used.
Manufacturer data
Some numbers come from products rather than codes, such as the yield of a bag of premixed concrete. We use the figures manufacturers print on their packaging and charts, note the date we checked them, and say so on the page.
Prices
Prices are never pre-filled. Material costs differ by region and season, so price fields start empty and an estimate appears only when you enter your supplier's price.
Reviews and changes
Each calculator shows the month it was last checked. When a formula changes in a way that moves a result, the method version on the page goes up and the change is recorded.
What a calculator is not
A calculator gives estimates for planning and ordering. It is not an engineering design and does not replace a permit drawing, a structural calculation or your building official's interpretation of the code. Found a mistake? Write to the address on the contact page; corrections are made within days.