Last updated: 7 September 2026
We respect copyright, and we expect the same. This page covers both directions: what to do if you think we have used your work without permission, and what we do when someone copies ours.
If you think we have infringed your copyright
Tell us and we will look at it properly. Most of these turn out to be a photograph whose licence changed or a quotation that grew past fair use, and both are fixed the same day once we know. Send the notice through our contact page and put “Copyright” at the start of the subject line.
For a notice under the Digital Millennium Copyright Act, United States law requires all six of these. A notice missing any of them still gets read, but it may not be actionable:
- Your physical or electronic signature, or that of someone authorised to act for you.
- What work you say was infringed. If several, a list of them.
- Where the infringing material is on our site: the full address of the page, and which image, paragraph or file on it you mean.
- How we can reach you: an email address, and a postal address or telephone number.
- A statement that you believe in good faith that the use is not authorised by the copyright owner, its agent, or the law.
- A statement that the information in the notice is accurate, and, under penalty of perjury, that you are the copyright owner or authorised to act for them.
Filing a notice you know to be false carries real consequences under the same law, including liability for the other side’s costs. Please be sure before you send one.
What happens next
We acknowledge every notice. Where the claim looks well founded we remove or replace the material promptly, usually within a few working days, and we tell you what we did. Where it does not, we explain why rather than ignoring you. If the material came from a contributor, we tell them what was removed and why.
If your material was removed and you disagree
Send a counter-notice through the same route, with your signature, an identification of what was removed and where it appeared, your contact details, a statement under penalty of perjury that you believe in good faith it was removed by mistake or misidentification, and your consent to the jurisdiction of the appropriate court. We will pass it to whoever complained and, if they do not go to court, the material may be restored.
Repeat infringement
Anyone who repeatedly posts infringing material loses the ability to contribute to this site. In practice there is almost nothing here to police: comments are closed, public account registration is closed, and everything published is written for us rather than posted by visitors.
Why there is no designated agent listed
The safe harbour in section 512 of the Digital Millennium Copyright Act protects a service from liability for material its users post, and it is claimed by registering a designated agent with the United States Copyright Office. Nothing on this site is posted by a user: comments are closed, registration is closed, and every article, calculator and image here is published by us. There is nothing for that safe harbour to shield, so there is no agent to name, and we would rather say that plainly than list one that does not mean what it appears to mean. Send a notice through the contact page and it reaches a person the same way.
If that ever changes, and the site starts carrying material written by its readers, we will register an agent before it opens and this section will be replaced by the registration.
Our own content
The articles, the calculators and their implementation, the design and the original images are ours or licensed to us. What you may and may not do with them is set out in our terms of use. Short quotations with a credit and a link back are welcome. Wholesale republication, scraped copies and cloned calculators are not, and we do send notices about them.
Images
Photographs on this site come from stock libraries under their licences, and we keep a record of the library, the photograph and the photographer for each one. If a photograph of yours appears here and you believe the licence does not cover it, tell us which page it is on and we will replace it rather than argue about it.