- Bedtime calculators at a glance
- Ten apps that do the sleep cycle sums
- Same sum, different starting assumptions
- Working backwards from the alarm, or forwards from now
- Alarms, naps, sounds and Apple Watch extras
- What the listings say these calculators can't do
- Using a bedtime calculator tonight
- My advice on choosing a sleep calculator
- Frequently asked questions
A sleep calculator app counts back from the time you need to get up, in sleep cycles of around 90 minutes plus a few minutes to fall asleep, and suggests bedtimes, or counts forward from now to suggest wake-up times. The apps here do broadly the same sum, but they don't all start from the same assumptions.
If you've ever woken up groggy and wondered whether it was the alarm's fault, sleep calculator apps are built around that question. You tell one when you need to be up and it suggests when to go to bed, or you tell it you're going to bed now and it suggests when to set the alarm.
Everything below comes from each app's own App Store listing, read as of Nov 2026, and the list is alphabetical and in no particular order. This isn't medical advice, and none of it claims an app will improve your sleep. If you're struggling with sleep, that's a conversation for your doctor, as one of the listings says itself.
Bedtime calculators at a glance
| Tool | Type | Good for |
|---|---|---|
| Bedtime Sleep Cycles (Zachary Howe) | Coloured clock for picking an alarm time | Red, yellow and blue sleep bands |
| Nighty: Sleep Cycle Calculator (Jonathan Toussaint) | Offline sleep cycle calculator | No tracking and no accounts |
| REM Sleep Calculator & Sounds (Giorgio Network) | Sleep calculator with sleep sounds | Rain, thunderstorm and white noise |
| Sleep Calculator Plus (Kevin Hausen) | Simple calculator with a dark design | No ads and no in-app purchases |
| Sleep Calculator Pro (DealWatch24) | Sleep cycle calculator with a tracker | About 15 minutes to fall asleep built in |
| Sleep Calculator: Bedtime (Lean Asia) | Bedtime and nap calculator | Four bedtimes for one wake-up time |
| Sleep Cycle Bedtime Calculator (Kai Oelfke) | Bedtime calculator for iPhone and Apple Watch | Checking times from your wrist |
| Sleep Timer - Smart alarm (Kodeon) | Sleep cycle counter with an alarm | A 14-minute fall-asleep time built in |
| sleepytime calculator (Artur Pokusin) | Bedtime and wake-up time suggester | Starting from how long you want to sleep |
| WakeUp, Sleep Cycle Calculator (Alejandro Apodaca) | Dial-based calculator with alarms | One-tap alarms for sleep and naps |
Ten apps that do the sleep cycle sums
Bedtime Sleep Cycles (Zachary Howe)
Best for: Dragging coloured bars around a clock to pick when to set your alarm, with red for the minimum sleep, yellow for fair and blue for optimal.
Nighty: Sleep Cycle Calculator (Jonathan Toussaint)
Best for: Using a wake-up mode or a bedtime mode to see times near cycle boundaries, with an adjustable fall-asleep time and every calculation done on the device.
REM Sleep Calculator & Sounds (Giorgio Network)
Best for: Finding the moments you'll be in your lightest sleep from a 90-minute cycle and your fall-asleep time, with sounds like light rain and white noise.
Sleep Calculator Plus (Kevin Hausen)
Best for: Working out a bedtime for a set wake-up time, or wake-up times if you go to bed now, in 12 or 24-hour format.
Sleep Calculator Pro (DealWatch24)
Best for: Choosing when you want to wake up and seeing when to go to sleep, or when to wake if you sleep now, plus bedtime notifications.
Sleep Calculator: Bedtime (Lean Asia)
Best for: Typing in a wake-up time to get four bedtimes that each land on a 90-minute cycle boundary, plus nap timing, wake reminders and sleep sounds.
Sleep Cycle Bedtime Calculator (Kai Oelfke)
Best for: Entering a wake-up time to see bedtime options, or a bedtime to see wake-up times, with an adjustable time to fall asleep and an Apple Watch app.
Sleep Timer - Smart alarm (Kodeon)
Best for: Counting sleep cycles with an average fall-asleep time built in, then setting an alarm in one click for the time it suggests.
sleepytime calculator (Artur Pokusin)
Best for: Getting suggested bedtimes and wake-up times based on the length of sleep you want and sleep cycles.
WakeUp, Sleep Cycle Calculator (Alejandro Apodaca)
Best for: Turning a dial to pick a bedtime or wake-up time, seeing the times that line up with full cycles, and setting a real system alarm.
Same sum, different starting assumptions
Read the ten listings together and the arithmetic is the same: whole sleep cycles plus the time it takes you to drop off. WakeUp says it 'plans your night in 90-minute sleep cycles', REM Sleep Calculator 'uses the average sleep cycle of 90 minutes', and Sleep Calculator: Bedtime promises 'four bedtimes that each land on the boundary of a 90-minute sleep cycle'. Sleep Timer puts the same idea as cycles 'each lasting 1.5 hours'.
Where they differ is the fall-asleep time. Sleep Timer counts on 'the average time needed for a person to fall asleep', which it puts at 14 minutes, and Sleep Calculator: Bedtime uses 14 minutes too. Sleep Calculator Pro says 'It takes an average human about 15 minutes to fall asleep', and Sleep Calculator Plus also works on about 15 minutes. It's a small gap, but it's why two apps can suggest slightly different bedtimes for the same alarm.
That's the bit you wouldn't guess from the app names: they're doing the same sum from slightly different starting points. Three let you move the starting point yourself. Sleep Cycle Bedtime Calculator lets you 'Adjust the time you need to fall asleep', Nighty says you can change it 'if you tend to fall asleep faster or slower than average', and Sleep Calculator Pro lists a 'configurable time to fall asleep'. WakeUp says it learns how long you take to fall asleep, on your device. sleepytime works from a different angle again, 'based on your desired sleep length and sleep cycles'.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
Working backwards from the alarm, or forwards from now
Every calculator here works in one direction or both. Sleep Cycle Bedtime Calculator says 'Enter your wake-up time to see bedtime options, or enter your bedtime to see wake-up options'. Nighty has a wake-up mode and a bedtime mode, Sleep Calculator Plus finds wake-up times 'if you are going to bed now', and Sleep Calculator: Bedtime has an 'If you sleep now' option counted from the current minute.
Bedtime Sleep Cycles takes a more visual route. You drag coloured bars around a clock face, where 'Red is the minimum time of sleep', yellow is 'a fair night of sleep' and blue is 'the optimal amount of sleep'. Nighty highlights five cycles, about seven and a half hours, by default, and says you're free to choose what fits your schedule.
Alarms, naps, sounds and Apple Watch extras
- Alarms. WakeUp sets 'Real system alarms that ring even in Silent mode or a Focus', Sleep Timer sets an alarm in one click, and Sleep Calculator Pro adds a smart alarm and a sleep tracker. Bedtime Sleep Cycles is upfront that it 'is not an alarm clock' and can only tell you when to set yours.
- Naps. WakeUp has a Nap button for a one-tap alarm, and Sleep Calculator: Bedtime includes a nap calculator that schedules a wake reminder.
- Sounds. REM Sleep Calculator lists sounds such as Light Rain, Thunderstorm, Summer Night and White Noise, WakeUp has ocean, rain and brown noise, and Sleep Calculator: Bedtime has eight synthesized sleep sounds.
- Apple Watch and Apple Health. Sleep Cycle Bedtime Calculator works on Apple Watch, and both it and WakeUp can connect to Apple Health to show your sleep history.
- Privacy. Nighty says 'All calculations happen on-device', and WakeUp says your sleep data stays on your iPhone and in Apple Health.
What the listings say these calculators can't do
The most useful lines on these pages are the careful ones. Sleep Cycle Bedtime Calculator says it 'uses fixed 90-minute cycle estimates; actual sleep cycles vary', and that it doesn't measure or predict your sleep stages. Nighty calls its suggestions 'a helpful guide, not medical advice'. WakeUp says it 'is not a medical device' and suggests talking to a doctor if you have ongoing trouble sleeping, and Sleep Calculator: Bedtime says 'The app never claims to measure your sleep'.
Using a bedtime calculator tonight
- Start from the time you have to be up, not the time you'd like to be up.
- Check the app's fall-asleep setting, and change it if the app lets you and you know you drop off faster or slower.
- Look at the bedtimes it offers and pick one you can stick to.
- Set the alarm in the app if it can, or in your phone's clock app if it can't.
- Treat the times as a guide, since one listing says sleep cycles vary from person to person.
Do you make a sleep calculator app? Tool makers can ask to be considered for a featured place on this list.
My advice on choosing a sleep calculator
Since they do much the same sum, choose on the extras you'll use. If you want the alarm set for you, pick one that says it sets a real alarm. If you want a plain answer and nothing else, the on-device calculators keep it simple. If you want sounds or naps, a few bundle those in. Whatever you pick, treat the times as a starting point rather than a rule.
If winding down is the hard part, my list of sleep apps for busy women goes wider than calculators, and my guide to meditation apps for stress at work may help with a busy head at bedtime.
Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.
Frequently asked questions
How does a sleep calculator app work?
It counts in sleep cycles, which are 90 minutes on eight of the ten listings here, and adds the time it takes you to fall asleep. Give it a wake-up time and it suggests bedtimes, or tell it you're going to bed now and it suggests wake-up times.
How long do these apps say it takes to fall asleep?
The listings differ. Two use 14 minutes, while three others say about 15 minutes. Some apps let you change the number to suit you.
Can a sleep calculator set my alarm?
Some can. One sets real system alarms that ring in Silent mode, and another sets an alarm in one click. One listing says it isn't an alarm clock and can only tell you when to set yours.
Does a sleep calculator track my sleep?
A calculator on its own doesn't. One listing says it doesn't measure or predict your sleep stages. Some apps add sleep history from Apple Health, or a separate tracker, alongside the calculator.
Is a sleep calculator medical advice?
No. One app calls its times a helpful guide, not medical advice, and another says it isn't a medical device and suggests talking to a doctor if you have ongoing trouble sleeping.
Are sleep calculator apps free?
Several are free to download, as of Nov 2026, and one says it's free with no ads. Others keep features such as alarms, sleep history or sounds behind a purchase or subscription, so check the listing first.
