This page explains how every calculator on CalcQuarry is made and checked, so you can decide how far to trust a result.
1. One formula, written once
Each calculation, such as the volume of a slab or the riser height of a stair, is a small function in the site’s code. The calculator you
use, the worked example on the page and the tables are all produced by that same function. The example numbers are generated when the page
is built, so they can’t drift away from what the calculator does.
2. Automated tests with hand-checked answers
Every formula has automated tests with answers worked out by hand: for example, a 10 × 10 ft slab 4 in thick with 10% extra must come to 62
bags of 80 lb mix, and a 108 in stair rise must give 14 risers. The tests run before every update is published, and a failing test blocks the
release.
3. Exact units
Conversions use exact definitions from NIST: 1 in = 2.54 cm and 1 ft = 0.3048 m exactly, and the US gallon is exactly 231 cubic inches. The
calculators keep full precision internally and round only for display. Anything counted in whole units, such as bags or blocks, is rounded
up, because you can’t buy part of a bag.
4. Sourced constants
Numbers that aren’t pure geometry, such as how much concrete a bag makes or how much a cubic yard of gravel weighs, come from a named
source: a manufacturer’s data sheet, an industry association, a university extension service or a building department. Each calculator
lists its sources with dates, and says in its hint text where a value varies (gravel weight, for example) so you can enter your supplier’s
figure instead.
5. Code rules are summaries
Where a calculator checks a code rule, it uses the International Residential Code as summarized in public building-department handouts.
Local amendments can differ, so these checks are a first pass, not an approval.
6. Reviews and corrections
Each page shows the date its formulas and sources were last reviewed. If you find an error, email
hello@calcquarry.com with the page link and your inputs. Confirmed errors are fixed and the page date
is updated.
7. Your data stays with you
Calculations run in your browser. What you type isn’t sent to our servers. See the privacy policy.
Sources used across the site
- Concrete Mix Product No. 1101 data sheet, QUIKRETE
- Mortar Mix Product No. 1102 data sheet, QUIKRETE
- CMU-TEC-001-23: Concrete Masonry Unit Shapes, Sizes, Properties, and Specifications, Concrete Masonry & Hardscapes Association
- Guide Spec PAV-GSP-011-21: Pavers on Aggregate Base, Concrete Masonry & Hardscapes Association
- Five handy rules of thumb for successful asphalt pavement construction, Asphalt magazine
- Landscape Materials Density Chart, North Bay Materials
- Screened Fill Dirt (Clay Blend), North Bay Materials
- How much does a cubic yard of topsoil weigh?, Topsoil.com
- Too much of a good thing: mulch volcanoes slowly kill trees, University of Illinois Extension
- Starting a New Lawn, University of Maryland Extension
- IRC Section R311.7.5: Stair Treads & Risers (Handout #437), City of Boise
- 2018 Residential Stair Guide (IRC R311.7), Town of Timnath, Colorado
- Asphalt Shingles (R905.2), City of Hopkins, Minnesota
- Glossary: Board foot, Virginia Department of Forestry
- Voluntary Product Standard PS 20-20: American Softwood Lumber Standard, NIST / American Lumber Standard Committee
- Span Tables for Joists and Rafters, 2024 edition, American Wood Council
- NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically, National Institute of Standards and Technology