About HardHatCalc
HardHatCalc is a free construction calculator suite for contractors, tradespeople, and DIY homeowners. You enter your project dimensions, and the tool gives you instant material quantities, cost estimates, or structural sizing results. No sign-ups, no paywalls, no ads (for now).
Who Built This
My name is Dan Dadovic. I'm a Commercial Director and PhD candidate in IT Sciences at the University of Zagreb. My day job is web development and publishing — I run calculatorcorp.com, a network of over 4,300 calculator pages spanning finance, health, math, and engineering.
I hold a double master's degree from the University of Zagreb and I'm currently finishing my PhD in IT Sciences. My academic background is in information technology and data analysis, not structural engineering — and I want to be upfront about that.
Where the Construction Data Comes From
In 2025, I moved to Northumberland in northeast England and bought a house that needed significant work. Over the following months I did room expansion, structural modifications, re-roofing, full interior painting, insulation upgrades, garden landscaping, and general repairs. Some jobs I did myself; others required tradespeople.
Through that process, I constantly needed calculators — how many shingle bundles for a 12/12 pitch roof, how many studs for a 20-foot wall with two window openings, what size beam replaces a load-bearing wall. The tools I found online were either too simplistic (no waste factor, no cost estimate) or too technical (structural engineering software that assumes you know how to read a steel beam table).
HardHatCalcfills that gap. Every calculator uses published construction formulas from industry references. The cost data comes from US national averages with dates and ranges — not point estimates presented as fact. Where I have hands-on experience with a topic, the content reflects that. Where I don't, the content sticks to the published data and says so.
What This Site Is (and Isn't)
This site provides estimates for planning purposes. The structural calculators can help you understand rough beam sizes, load capacities, and material quantities — but they are not a substitute for a licensed structural engineer. Building codes vary by jurisdiction. If your project involves load-bearing elements, get a professional to review the plans.
The materials calculators give you quantities and cost ranges so you can plan purchases and set budgets. Actual costs depend on your region, supplier, material grade, and time of year.
I'm a publisher and PhD candidate, not a structural engineer. I build web tools using published formulas and real-world data. The calculators are honest about their limitations, and every page shows the formulas used so you can verify the math yourself.
Contact
Found a bug? Have a feature request? Use the contact form to get in touch. I read every message.