Accessibility and reporting a problem
Use the skip link to reach the main content, headings to navigate an article, and the visible labels beside form fields. If a feature is difficult to use, report the page address, intended task and what happened. Include browser or assistive-technology details when helpful.
Content and interactive features
Reference text, tables and diagrams are provided with the page. Calculators include formulas and worked examples; a normal form submission also returns a result when JavaScript is unavailable. The optional My Equipment feature requires JavaScript and local browser storage.
The contact form uses ordinary labeled fields. Verification may load when JavaScript is active. If a submission fails, retain your message and note the error text rather than assuming it was delivered.
Accessibility target and verification limits
The accessibility target is Level AA of the Web Content Accessibility Guidelines. Automated markup checks can detect some label, heading, landmark and alternative-text problems. They do not establish a complete experience for a person using assistive technology.
Independent screen-reader testing and a complete visual contrast review have not been verified for this revision. An accessibility report can identify an issue that an automated check missed.
Send a reproducible report
- Copy the full page address.
- Describe the control or text you were using and the result you expected.
- Quote the error or describe the unexpected behavior.
- Include the browser and assistive technology, if applicable.
Send the details through contact. For example, “Calculate announced an error but focus stayed on the button” identifies a specific interaction. Avoid including private information that is unnecessary to reproduce the issue.
Legal
Accessibility statement
This states what the site’s own code does for accessibility, each item described here with the current keyboard and form behavior, and separates that from what has not yet been independently verified: no page here has been tested by a person using a screen reader, and a full color-contrast measurement sweep has not been run. The site targets WCAG 2.1 Level AA. A skip link, one visible heading per page with no skipped levels, alt text on every image, a labeled control on every calculator field, and ordinary keyboard-operable HTML rather than custom widgets are all built in and available to keyboard users; screen-reader testing and a contrast sweep are not yet done, and this page says so rather than claiming otherwise.
Reviewed 2026-10-18.
What this page is
This describes what the site's own code does for accessibility, described here with the current keyboard and form behavior using the controls described here. It is not a claim of full compliance with any standard: no page here has been tested by a person using a screen reader, and the statement below says exactly that rather than a stronger claim we have not verified.
What is built in, and how it is checked
| Feature | What it does |
|---|---|
| Skip link | A "Skip to main content" link is the first focusable element on every page, so a keyboard or screen-reader visitor does not have to tab through the header on every page load. |
| Landmarks and heading order | Every page carries exactly one visible top-level heading, navigation and footer are marked as landmarks, and heading order should follow the visible sections. |
| Images | Every image and diagram carries alt text, or is marked decorative when it repeats text already on the page. Report a problem through the contact form on any image with neither. |
| Form controls | Every calculator field on every tool carries a visible, associated text label. Report a problem through the contact form on any control it cannot find one for. |
| Link text | Links are written to make sense out of context; report unclear link text such as "click here" or "read more" standing alone. |
| Keyboard operation | The site uses ordinary HTML links, buttons and form controls rather than custom widgets, so standard keyboard navigation (Tab, Shift+Tab, Enter, Space) works without any custom scripting to maintain. |
| Color contrast | Body text is set in dark text on a light background at a ratio intended to clear WCAG 2.1 AA (4.5:1 for normal text), but this has not been re-verified against every color combination on every page with a contrast-measurement tool, so it is stated as intent and design, not as a tested guarantee. |
| Motion | The site has no auto-playing video, no auto-advancing carousel and no animation that cannot be paused, because none of those things exist on the site at all. |
What is not yet independently verified
The items above are described in the current implementation, which is different from a person using assistive technology confirming the experience works for their needs. Screen-reader testing with a real tool (VoiceOver, NVDA or JAWS), a full-page color-contrast sweep with a measurement tool rather than a design intent, and a review against the complete WCAG 2.1 Level AA success criteria have not been done. This statement will be updated, and this section shortened, as each of those is completed.
Standard targeted
Where this site sets out to meet a standard rather than simply describing what it does, the target is WCAG 2.1, Level AA, published by the W3C Web Accessibility Initiative.
Known limits
The calculators provide JavaScript interaction and an ordinary HTML submission path. Without scripting, enter the values and submit the form for its HTML result. The assumptions, formula and worked examples also remain readable, so the arithmetic and its limits can be checked independently.
Reference text, tables, diagrams and question answers remain readable when browser scripting is disabled. Interactive features and calculator submission behavior are described separately above.
Reporting a problem
If something on this site is difficult or impossible to use with a keyboard, a screen reader, or any other assistive technology, tell us through the contact form, naming the page and what happened. That report is treated as an accessibility issue: include the page, the control and the steps that produced the problem so it can be investigated.