Last updated: January 2026
Purpose
This document discloses the sources behind reference material shown on ConstrCalc® — guides, standard quantities, country practices, glossary. It does not disclose sources for user-supplied data, because user-supplied data has no source but the user.
Standard Material Quantities (per 1,000 ft²)
- Cement 400 bags, sand 81.6 ton, steel 4,000 kg, bricks 8,000 pcs, aggregate 1,350 ft³, paint 2.5 gal
- Origin: Conservative Indian/South Asian residential RCC (Reinforced Cement Concrete) construction norms popularized in field manuals and cross-referenced against practitioner data.
- Applicability: Regional; verify locally. Use Manual Entry when standards diverge.
Cost Reference Ranges
- Cement $6–$12/bag, sand $20–$45/ton, steel $0.60–$1.20/kg, bricks $0.25–$0.60/pc, aggregate $1.00–$2.20/ft³, paint $30–$60/gal
- Origin: Aggregated retail/wholesale pricing from major North American home-improvement retailers and construction supplier catalogs, sampled quarterly.
- Volatility: These are point-in-time reference values, not price predictions. Prices vary materially by location and market conditions. Always use your actual quotes in the calculator.
Country-Specific Practices
- Origin: Publicly available national/municipal building code references (IRC/IBC USA, Building Regs UK, DIN Germany, SANS South Africa, NBR Brazil, BCA/NCC Australia, etc.) and government revenue portals for tax rates.
- Applicability: Country practice notes are broad summaries. Consult a licensed local professional for project-specific requirements.
Glossary
- Origin: Composite of standard construction industry usage across US, UK/Commonwealth, and international practice. Cross-regional variance (e.g., punchlist vs snag list) noted where relevant.
Labor & Permit Reference Values
- Origin: US Bureau of Labor Statistics (BLS) for national wage benchmarks; state and municipal permit fee schedules for typical permit ranges; sampled from public data.
Currency & Unit Conversion Constants
- Deterministic mathematical constants only:
- 1 m² = 10.7639 ft²
- 1 m³ = 35.3147 ft³
- 1 US Ton = 907.185 kg; 1 Metric Ton = 1,000 kg
- 1 US Gallon = 3.7854 L
- Currency exchange rates shown in the selector are illustrative labels — ConstrCalc does not convert user-entered monetary values between currencies.
Correction Policy
If you find a factual error in any of our reference material, please contact us. Substantive corrections are published with a dated note on the affected page.
Not A Substitute For Professional Advice
All reference material is informational. For real-project decisions, consult a licensed professional in your jurisdiction. See our Disclaimer.