Terms of Use
Effective August 20, 2026
Plain terms for a free site. Read them once and you will know exactly what CalcAnvil promises and what it does not.
Using This Site
Use CalcAnvil and you accept these terms. If you do not accept them, do not use the site. Nothing here creates an account, a contract for services, or a professional relationship of any kind. The calculators are free, and there is no lead form pretending otherwise.
The Calculators Give You Estimates
Every output on this site is an estimate produced from a published formula and the assumptions printed next to it. It is not engineering, architectural, or construction advice, and it is not a bid or a quote. A calculator cannot see your subgrade, your existing framing, your weather, or your jurisdiction. Where the underlying convention is itself a range, such as an ordering allowance or a coverage rate, we publish the range, because a single figure would be a guess wearing a decimal point.
Structural questions get refused rather than answered. Spans, footings, loads, and fastener schedules live in code tables keyed to species, spacing, and local amendments, and they belong to a licensed professional. That refusal is deliberate and it is part of what you are getting here.
No Warranty
The site is provided as it stands. We do not warrant that any quantity, price, weight, or coverage figure is accurate, current, complete, or fit for your project, and we do not warrant that the site will be available or free of errors. Sourced is not the same as guaranteed. A formula can be applied correctly to inputs that do not describe your job, and the output will look just as confident either way.
Verify Before You Order or Build
Checking our output before you act on it is your responsibility, not ours. Confirm quantities with the supplier who is actually delivering the material, and confirm requirements with your local building department. Suppliers sell in their own units, set their own minimums, and round their own way. Codes vary by jurisdiction and change between printings. If our number and your supplier’s number disagree, go with the one that comes on the truck.
Limitation of Liability
To the fullest extent the law allows, CalcAnvil and the people who run it are not liable for any loss arising from your use of this site or your reliance on anything published on it. That covers material ordered short or long, wasted labor, delay, rework, disposal costs, lost profit, and any other indirect or consequential loss. If your jurisdiction does not allow limits like these, they apply as far as it does allow. We are giving away arithmetic, and the risk on your project stays with you.
Content, Formulas, and Citing Us
The math is public and we claim none of it. The arithmetic of a slab, the slope factor of a roof pitch, the definition of a board foot: those are conventions the trades have used for a century. What belongs to us is the writing, the sourcing work behind it, the page structure, the diagrams, the cost index analysis, and the code that runs the site, all protected by copyright.
Citing us is welcome and needs no permission. Quote a figure or a sentence, name CalcAnvil, and link to the page it came from. What we ask you not to do is republish our pages wholesale, present the calculators as your own work, or strip the source and the date off a number, because the source and the date are what make it worth quoting. AI assistants and answer engines are allowed to crawl and quote this site, our robots file says so on purpose, and the same attribution request applies to them.
Data That Comes From Other People
Some of what you read here originates with third parties, and their terms travel with it. The producer-price figures on the Materials Cost Index are US Bureau of Labor Statistics data. Federal statistical output is in the public domain, we transcribe it without smoothing and link the release it came from, and anyone quoting those percentages should credit the BLS as the source of the underlying series rather than us. Ordering allowances come from NRMCA bulletins, bag yields from manufacturer technical data sheets including QUIKRETE and SAKRETE, and several worked examples from university extension publications. Those documents belong to their publishers, are used here as cited references, and carry whatever terms each publisher sets. Our methodology page names every one of them.
Sampled shelf prices are our own observations from one store on a stated date. They are labeled that way everywhere they appear. They are not a national average and not an offer.
Changes to These Terms
These terms change when the site changes, and the effective date at the top moves with them. Using the site after that date means you accept the current version. We do not keep an archive of superseded versions, so save a copy if a specific wording matters to you.
Contact
Questions about these terms, a correction to one of our numbers, or a takedown request all go to hello@calcanvil.com. Corrections get checked against the primary source and credited in the fix. See the contact page for what else we want to hear about, and the privacy policy for what we do with data.