About us
Septic & Drainage Calculators is a free online resource providing easy-to-use calculators for septic systems, drainage projects, excavation, and related property improvement projects.
Our purpose
Our goal is simple: make common project calculations easier to understand and perform.
Septic & Drainage Calculators provides free calculators that can help homeowners, property owners, DIYers, contractors, and other visitors estimate measurements, quantities, volumes, slopes, and other project-related values.
The calculators currently on the site are:
- Septic Tank Volume Calculator
- Daily Wastewater Calculator
- Perc Rate Calculator
- Drain Field Area Estimator
- French Drain Gravel Calculator
- Drain Pipe Slope Calculator
- Pipe Drop Calculator
- Drainage Stone Calculator
- Rainfall Runoff Calculator
- Trench Volume Calculator
- Excavation Volume Calculator
- Soil Weight Calculator
We may add additional calculators and educational resources as the website grows.
How our calculators work
Our calculators use mathematical formulas and information entered by the user to generate estimates. Everything runs inside your browser — your measurements are not sent to a server, stored, or associated with you.
Whenever possible, we explain the formulas, assumptions, and measurements used so visitors can better understand how a result was calculated. Every calculator page shows the formula it uses, a worked example, and a step-by-step breakdown of the arithmetic behind your own result.
We work to make our tools useful and accurate, but calculator results should be considered estimates rather than professional recommendations or guaranteed project specifications.
Important information about septic and drainage calculations
Septic systems, drainage systems, excavation projects, and similar work can be affected by local building codes, environmental regulations, soil conditions, site conditions, permits, setbacks, system design requirements, and other factors. Requirements can vary significantly between states, counties, municipalities, and individual properties.
Our disclaimer sets out in more detail what these tools do and do not tell you.
Free to use
Our calculators are provided free of charge. There is no account to create and no sign-up.
To help support the operation and continued development of this website, Septic & Drainage Calculators may display advertising and may use third-party advertising services such as Google AdSense. Our privacy policy explains how that works.
Our commitment
We aim to provide a website that is:
- Easy to use
- Fast and mobile-friendly
- Transparent about calculations
- Helpful for project planning
- Regularly improved as new tools and information are added
If you find an error or have a suggestion for a calculator you would like us to add, we welcome your feedback.
Contact us
Questions, corrections, suggestions, or other feedback can be submitted through our contact page.
Thank you for visiting Septic & Drainage Calculators.