Thurston Laboratories, LLC offers a growing collection of professional engineering calculators free of charge to the design community. Each tool runs in your browser with no software to install, no license fee, and no watermark on the results. Whether you are sizing a septic leach field, designing a concrete mix per ACI 211.1-22, analyzing lateral earth pressures on a retaining wall, or working through Manning’s equation for pipe or open-channel flow, these calculators are built to give you clear, code-aware answers in minutes—not hours in a spreadsheet.
Engineers, architects, and other design professionals can download fully white-label PDF reports carrying your company name, logo, and project metadata, ready to drop into a submittal or client package. Homeowners exploring a property improvement and students checking coursework will find the same straightforward workflows and transparent calculations. Thurston Labs built these tools from real project work and classroom practice; we are pleased to share them with the community at no cost.
These tools are provided free of charge, without warranty, for preliminary planning and education only—not engineering, legal, or regulatory advice. Verify all project requirements before use; construction and submittal work should be reviewed by a licensed professional. Thurston Laboratories, LLC disclaims liability for use of these calculators and for decisions made in reliance on their output. If you find an error in any of these calculators, please let us know.