Page updated
Editorial and corrections policy
A clock time is only as good as the figures behind it. This page says how a figure gets onto Lull, how we keep it current and what happens when one is wrong.
Where our figures come from
We prefer, in this order: the pages of government health bodies (the CDC and its NIOSH institute, NIH institutes, the NHS, the Canadian and Australian health departments, the FDA and USDA); guidance those bodies publish for travellers and shift workers, such as the CDC Yellow Book and NIOSH's training for nurses; and peer-reviewed studies, named where they are used. We do not base a figure on blogs, product sellers, news articles or summaries written by other sites or by AI tools.
How a figure gets onto the site
- We read it on the source page itself, in a browser, not in a search snippet or a summary, and copy the words that show the figure (for a USDA food record, the record's own figures).
- We add it to our data file with its value, unit, source link, the year of the source, the date we read it, a tier (below) and those words.
- We add it to the source check (below), so it cannot go stale unnoticed.
- We rebuild every page from the data file. No figure is typed into a page by hand: the worked examples and tables are generated, and the build fails if a page shows a number that does not come from the data, or a worked example the calculator would not give.
Three tiers
Each of the 129 values is tagged on the methodology and sources page:
- Primary (106): read straight off the cited page and used as published, apart from unit conversion.
- Secondary (1): reported by the cited page from another body, which is named in the row.
- Studio rule (22): a figure we chose because no source gives one, such as the minutes allowed for falling asleep. Each says what it leans on, and the 5 that lean on no source say so.
How we write about health
The calculators give clock times and amounts. They never recommend an amount of anything to take and never say what is wrong with anyone. Where a page describes a step, such as when to seek light after a flight, it is quoted from and credited to its source; where we had to set a figure ourselves, such as the 6 hour caffeine stop before sleeping after a night shift, it is labelled a studio rule. Every tool has a “Limits of this estimate” box saying what it cannot know and when to see a doctor.
Keeping figures current
Every quarter a script opens each source page on the list and flags any whose figure has changed; pages that block scripts are read by hand. When a figure changes, we update the data file, rebuild every page that uses it and add an entry to the changelog with the old and new value. A row's “last checked” date changes only when we have read its source again.
Testing
Every calculator is checked against cases worked out by hand from the data, and the checks run on every build. They are listed in full on how we test; if one fails, the site is not rebuilt until it passes.
Corrections
If you think a number is wrong, a source has moved or a page says something its source does not, email support@instacalc.co with the page, the figure and, if you have one, the source you are comparing with. We check the figure against its source. If it is wrong, we fix the data, rebuild the affected pages and log the correction in the changelog with the date and what the page said before. We do not change a published figure silently, and wording that changed what a page told readers is logged the same way.
Independence
Lull is paid for by advertising served by Google. Advertisers have no say in what the calculators show, we take no paid placements or sponsored content, and no ad appears inside a calculator or its result. Who runs the site is on the about page.