Terms of Use
Last updated 3 September 2026
Short version: the calculators are free to use, they are estimates for planning, and you should have anything structural, electrical or safety-critical checked by a qualified professional before you build it.
Using the site
AllMyCalculators is free to use. You may use the results for personal or commercial work — quoting a job, ordering materials, sizing a system.
You may not:
- scrape or bulk-copy the calculators or their content to republish elsewhere;
- present the results as your own professional certification or sign-off;
- attempt to disrupt the site or its hosting.
The calculators are estimates
Every calculator here implements a published formula, and the arithmetic is tested. That is not the same as being right for your situation. A calculator does not know your soil, your local code, your building's condition, the actual product you bought, or what the drawing left out.
Treat every result as a starting point for planning, not an answer to build from.
Where professional advice is required
Some of these calculations sit close to things that hurt people or cost a great deal when they are wrong. For anything in these areas, have the figures checked by someone qualified and insured:
- Structural — foundations, beams, columns, retaining walls, anything load-bearing.
- Electrical — circuit design, conductor sizing, protective devices, anything connected to a supply.
- Gas, heating and pressure systems.
- Anything covered by building regulations or local code, which vary by country and state and are not reflected here.
Rules of thumb on this site are marked as such. A rule of thumb is a starting point for a conversation with an engineer, not a substitute for one.
No warranty
The site and its calculators are provided "as is", without warranty of any kind, express or implied. We do not warrant that results are accurate, complete, current, or fit for any particular purpose, or that the site will be available without interruption.
Limitation of liability
To the fullest extent permitted by law, we are not liable for any loss or damage arising from your use of this site or reliance on its results — including materials ordered incorrectly, work that has to be redone, project delays, or any indirect or consequential loss.
Nothing in these terms excludes liability that cannot lawfully be excluded, including liability for death or personal injury caused by negligence, or for fraud.
Content and intellectual property
The formulas themselves are public knowledge and nobody owns them. The explanatory text, page structure, design and code of this site are ours. Quote a sentence with a link if it is useful to you; do not republish pages wholesale.
Changes
These terms may change; the date at the top shows when they last did. Continuing to use the site means you accept the current version.
Contact
Questions about these terms, corrections, and reports of a calculator giving a wrong answer all go to hello@allmycalculators.com.