About
A sleep calculator that tells you what it assumed
There are dozens of sleep calculators. They all run the same three lines of arithmetic on the same borrowed assumption, and almost none of them mention that the assumption is an average with a very wide spread. That gap is the entire reason this site exists.
What this is
Two things. A sleep calculator that takes a wake-up time and counts backwards in sleep cycles, and a small library of field notes that explain what the calculator is doing and how much confidence its output deserves.
The calculator is deliberately conventional. It uses the same 90-minute cycle and the same 15-minute fall-asleep allowance that everyone else uses, because those are reasonable central estimates and because a tool that produced idiosyncratic answers would be less useful, not more honest.
What is different is everything around it. The four assumptions are printed on the homepage. Cycle length is a slider, not a hard-coded constant. Short nights are flagged as short. And the article that asks whether sleep calculators work at all concludes that the category's central claim is unproven — which is an odd thing to publish next to your own calculator, and is the point.
Why bother being this careful
Because sleep advice is a field where confident, round, unsourced numbers travel further than accurate ones, and because the cost of that lands on readers rather than publishers.
The 90-minute sleep cycle is the clean example. The original descriptive work put individual cycle length at roughly 70 to 120 minutes. What propagated was the midpoint, stripped of its range, restated as a constant, and eventually presented as the basis for a precise bedtime. Nobody lied. The uncertainty just fell off in transit.
Once you have noticed that pattern you cannot publish the tidy version in good conscience. So this site states ranges, names its sources, and says "I could not find evidence for this" where that is the truthful answer.
The standard applied here
Every factual claim links to a source. Where two respected bodies disagree, both figures are shown. Where a claim rests on a single study, that is stated. Where the honest answer is that nobody knows, that is what gets written — including when a more confident answer would sell the calculator better.
Who writes it
One named person, Chaitanya Banerjee, a third-year medical student at Manipal Tata Medical College who writes every article on the site. Three years of medical school is enough training to read a paper properly and nowhere near enough to be a doctor — the author page is explicit about both halves of that, and it is worth reading before you weight anything here.
Nothing on this site is published anonymously or under a house byline. If a claim here is wrong, there is a specific person to hold responsible for it, and a public log where the correction goes.
How it makes money
At the moment, it does not. There is no advertising, no affiliate scheme, no supplement sponsorship, no mattress rankings and no email list. The calculator is free and does not require an account.
If that changes, it will be disclosed here and on the affected pages before anything else happens, and the rule will be that no commercial relationship may influence a factual claim. The reason to say this now, while there is nothing to disclose, is that it is much easier to commit to in advance.
What this site will not do
- Diagnose you. This is general information about sleep in healthy adults. It cannot examine you and it is not medical advice.
- Promise you will wake up refreshed. The mechanism behind that claim is not established, and asserting it would be the single easiest way to make this site more persuasive and less true.
- Sell you a sleep product. Not currently, and if ever, not without disclosure.
- Quietly edit its mistakes. Corrections are dated and logged.
Start with the tool
Enter the time you need to be up. Every assumption behind the answer is on the same page.
Open the sleep calculator