K. Lynch
Site Owner & Calculator Author — Home Project Calculator
I'm the person behind Home Project Calculator — a library of 60+ free construction and material estimating tools for homeowners, DIYers, and contractors.
I started this site because I kept running into the same frustration when planning my own home improvement projects: online calculators either gave results without explaining their assumptions, used vague formulas that didn't reflect how materials are actually measured, or produced outputs that didn't match what suppliers quoted me. I wanted tools that were transparent, accurate, and built on the same logic a professional would use — so I built them.
Every calculator on this site is built using documented formulas, defined unit conversions, and clearly stated assumptions for waste, coverage, and depth. Where calculators cover structural or safety-critical topics, I bring in external reviewers with relevant professional experience to verify the logic. The full review process is described on the Review Board page.
What I Actually Know
I'm not a licensed engineer or professional contractor — and I don't claim to be. What I bring is a practical working knowledge of home improvement built through years of hands-on projects, a genuine obsession with getting the maths right, and a commitment to being transparent about every assumption the calculators make.
The calculators covering concrete, structural framing, roofing, and electrical are reviewed by qualified professionals before publication. Their names and credentials are listed on each relevant page.
My Projects
These are real projects I've worked on. Getting hands-on with roofing, fencing, drainage, and water collection is part of what drives the attention to detail in the calculators — these are the kinds of jobs where an inaccurate estimate actually costs you money.
Roof Vent Installation
Installing a turbine vent to improve airflow and reduce heat buildup in the roof cavity. Planning this job is what prompted me to build more detailed roofing calculators — roof area and pitch measurements matter a lot when ordering materials.
Completed Roof Vent (Close-Up)
The finished installation. Proper ventilation manages moisture and heat, which affects how long a roof lasts — something that came up repeatedly when building the roofing calculator content.
Rainwater Tank Installation
Connecting a rainwater tank to the roof downpipe. A good reminder that roof area and drainage capacity are practical numbers — not just abstract calculations.
Fence Installation
Installing a steel fence along the property boundary. Accurate post spacing and panel counts make a real difference on fencing jobs — which is exactly what the fence calculators are designed to handle.
How the Calculators Are Built
Each calculator starts with the standard industry formula for that material or project type. I document the assumptions — waste allowances, coverage rates, density values, unit conversions — directly on the page so users can see exactly how results are produced and adjust if their project differs from the defaults.
- Formulas documented with sources and unit definitions
- Edge cases tested across irregular shapes, fractional units, and rounding
- Assumptions disclosed on each tool's page
- Last-reviewed dates maintained on all calculator pages
- Structural and safety-critical pages reviewed by qualified professionals
Full methodology is available on the Methodology page. Reference standards and data sources are listed on the Data Sources page.
Some of the Calculators I've Built
Get in Touch
For calculator feedback, corrections, or suggestions for new tools, use the contact page. I read every message and genuinely use the feedback to improve the site.