Four quick questions. Everything else is set from your baby's age and you can change any of it later in settings.
Settings
Numbers start from your baby's age. Adjust anything that doesn't fit — this is your baby, not an average.
Baby
Wake windows & naps
The stretch of awake time your baby can handle between sleeps, and how naps are scored.
A wake window before each nap, then before bed — it's normal for them to get longer as the day goes on. These are starting points from age norms. Every baby runs a little different, so adjust freely; the windows are a guide, not a rule.
Healthy overnight band
Used for the split-night check. Overnight sleep above the high end is the split-night zone; below the low end is on the short side.
Which hints to show
Turn off anything that isn't useful for your baby.
Log checkboxes
These are the things you tick each night. Turn off what you don't track, or add your own.
Hi! 👋
Hi! I'm happy you're here. If you're like me, you obsessed over your baby's sleep and desperate for sleep help, spent hours on the internet (thanks r/sleeptrain!) poring over suggestions and sleep help. As someone with a low sleep needs baby, it felt impossible to understand the schedule and keep everything in my head math-wise while on low sleep. Other sleep apps were helpful to a point, but nothing matched exactly what I needed. So I made this calculator just for me to use. Simple, tailored to my baby, editable. I tried to find patterns with it and am still working on it! I have a 10m old as of July 2026 :) but I wanted to share it with anyone who might need the help that I did.
What really helped me the most was the moderators and fellow parents in r/sleeptrain so check those out if you're desperate to understand baby's sleep more. If nothing is working and you're just trying to hang on, hopefully this sleep calculator can work for you. It's free to use and stores info every day. Disclaimer: there are a few affiliate links at the bottom if you're interested in what my most-used items are as a first time mom!
If you have questions or have suggestions, please email me @ angie@babysleepcalc.com with the subject line SLEEP CALCULATOR.
FAQ
Quick answers. Still stuck or have an idea? Email me (bottom of this list).
How do I back up my data?Under Daily History, tap Copy backup. It copies a readable, restorable block of text — paste it somewhere safe like a note to yourself or an email. Do this every so often, especially before clearing your browser or switching phones.
How do I restore from a backup?Tap Restore backup and paste the whole thing you saved — including the line that starts === RESTORE DATA === and everything below it. That replaces your current history with the backup.
Where is my data stored? Can you see it?No — everything lives only on this device, in this browser. Nothing is uploaded and I can't see any of it. The trade-off: it doesn't sync across devices, and clearing your browser data (or using private/incognito mode) erases it. So keep a backup.
How much sleep does my baby actually need?The American Academy of Sleep Medicine (endorsed by the AAP) recommends, per 24 hours including naps:
Those totals are the reliable part. How they split between night and naps isn't fixed by any authority — it's an average, and it shifts with age and with your specific kid.
So how do I figure out the nap vs. nighttime split?Start from the age total, subtract typical overnight sleep (roughly 10–11 hours for most babies past ~4–6 months), and whatever's left is naps. This app does that math live — the dashboard shows implied overnight = total − naps. Example: a 10-month-old needing ~13h who sleeps ~11h overnight has about 2h of naps to spend. Nap counts drop from 3 → 2 → 1 across the first two years.
What's a wake window?The stretch of awake time a baby can handle between sleeps. Short for newborns, longer with age — very roughly 2–2.5h around 6 months, 3–4h around 12 months, longer past age 2. You can set one per nap in settings (gear icon). It's a guide, not a rule: watch your baby's tired cues, not just the clock.
What's the "awake target"?Total hours awake across the whole day. The app uses it to project bedtime: wake time + awake target + total nap time = bedtime. If real bedtimes keep landing off, log a few actual ones in the dashboard and it'll suggest an adjustment.
Why is the projected bedtime so early sometimes?Short naps "use up" less of the day, so the math can push bedtime earlier than is healthy — which is a classic setup for a split night (baby up for a chunk in the middle). That's what the earliest bedtime floor guards against. Hold bedtime near the floor instead of dropping it.
My baby doesn't match the default numbers. Is something wrong?No. The starting numbers come from age averages, and plenty of babies (mine included) run outside them — that's normal. Edit anything in settings to fit your actual kid. That flexibility is the whole reason this exists.
Can I turn off the hints?Yes — gear icon → Which hints to show. Toggle off anything that isn't useful for your baby.
Where can I learn more?r/sleeptrain — the mods and parents there taught me most of what I know, and the wiki collects the good stuff. For the sleep-total numbers, the AASM/AAP consensus is the anchor. For age charts and wake windows, Precious Little Sleep and Huckleberry are commonly referenced starting points.
How do I reach you or suggest a feature?Email angie@babysleepcalc.com with the subject SLEEP CALCULATOR.