Most babies are ready to move from a bassinet to a crib between 3 and 6 months of age, though the exact timing depends on your baby’s size and development. The transition works best when you watch for specific readiness signals, set up the crib environment carefully, and introduce the new sleep space gradually rather than all at once.
When Your Baby Is Ready for the Crib
The single clearest signal is rolling. As soon as your baby shows any signs of being able to roll, it’s time to move them to a crib. Most babies begin showing these early signs around four months. A bassinet’s shallow sides and smaller sleep surface aren’t designed for a baby who can shift their own body weight, and continued use becomes a safety concern quickly.
Rolling isn’t the only trigger. Many bassinets have weight limits (often around 15 to 20 pounds, though this varies by model), and some babies hit that threshold before they start rolling. If your baby seems cramped, is bumping the sides frequently, or is pushing up strongly during tummy time, those are all signs the bassinet is getting too small.
The CDC recommends keeping your baby’s sleep area in the same room where you sleep for at least the first six months. That means you can place the crib in your bedroom initially. You don’t have to move the baby to a separate nursery at the same time you switch to a crib. Separating these two changes actually makes the whole process easier.
Handle the Swaddle Transition First
If your baby is still being swaddled, you’ll need to stop before or during the crib switch. Once a baby shows signs of rolling, swaddling is no longer safe because they need free arms to push themselves up and reposition if they roll onto their stomach. Most babies are ready to drop the swaddle between 3 and 6 months, which is the same window when the startle reflex (the involuntary arm-flinging that wakes them) naturally fades.
Signs your baby is ready to lose the swaddle:
- Attempting to roll when unswaddled
- Pushing up on hands during tummy time, especially lifting one hand off the ground
- Fighting the swaddle or fussing when it goes on
- Trying to free their hands up near their face while wrapped
- The startle reflex has faded, even if rolling hasn’t started yet
A sleep sack with open arms is the easiest middle step. It keeps the cozy, enclosed feeling your baby is used to while freeing their arms. Some parents do one arm out for a few nights, then both arms out, before switching to a full sleep sack. Tackling the swaddle change a week or two before the crib move means your baby isn’t adjusting to two big shifts at once.
Set Up the Crib for Safe Sleep
The crib mattress should be firm and flat, covered by a single fitted sheet. That’s it. No pillows, blankets, bumper pads, stuffed animals, or positioners. A bare crib looks sparse, but it’s the safest sleep surface for a baby.
Room temperature matters more than most parents realize. The recommended range is 68 to 72°F, though some research suggests the sweet spot is actually a bit cooler, between 60 and 68°F. A slightly cool room supports deeper sleep and reduces overheating risk. Dress your baby in a sleep sack appropriate for the room temperature rather than adding loose blankets. If you’re unsure whether your baby is too warm, touch the back of their neck or chest. Hands and feet tend to run cool naturally, so they’re not a reliable gauge.
Humidity in the nursery should stay between 30 and 60 percent. For babies, aiming toward the higher end of that range, around 55 percent, can help keep nasal passages comfortable, which means less congestion disrupting sleep.
White Noise Placement
If you use a white noise machine, place it at least 30 centimeters (about 12 inches) from the crib and never at maximum volume. A study testing 14 popular white noise devices found that nearly two-thirds exceeded safe noise thresholds when set to max volume and placed close to a baby. At minimum volume or at a reasonable distance, none of the devices exceeded those limits. Low to moderate volume across the room is the safest approach.
Why the 4-Month Mark Feels So Hard
Many parents attempt the crib transition right around four months, which unfortunately coincides with a major shift in how babies sleep. In the early weeks, babies spend most of their sleep time in deep sleep. Around four months, their sleep architecture reorganizes to cycle between deep and light phases, more like adult sleep. This means more partial wake-ups throughout the night, which can look like a sudden regression even though it’s actually a sign of brain maturation.
This is frustrating timing, but it’s also an opportunity. A baby who learns to fall asleep in the crib from an awake state during this period is practicing a skill that pays off for months. When they surface into lighter sleep at 2 a.m., they already have the experience of settling themselves in that same space. Babies who are always rocked or fed fully to sleep and then placed in the crib don’t get that practice, which often means more overnight wake-ups during the transition.
A Gradual Approach That Works
Going cold turkey works for some families, but a phased approach tends to produce less resistance and fewer sleepless nights. Here’s a practical way to spread the change over one to two weeks.
Week one: daytime familiarity. Let your baby spend awake time near or in the crib during the day. Supervised play on the crib mattress, diaper changes nearby, even a short nap or two in the crib while you’re present. The goal is to make the crib a familiar, neutral space rather than a strange new place that only appears at bedtime.
Start with one nap. Once your baby seems comfortable in the space, begin putting them down for one nap per day in the crib. The first nap of the day tends to be the easiest because sleep pressure is highest. Don’t worry if these naps are shorter than usual at first.
Move to nighttime. After a few days of successful crib naps, shift bedtime to the crib. Keep the crib in your room if your baby is under six months, or if you’re not ready for a full room change yet. The first few nights are typically the hardest. Expect some protest, and expect to offer comfort more often than usual.
Then the room change, if applicable. Once your baby is sleeping consistently in the crib, you can move it to the nursery. A video monitor can ease the anxiety of not being in the same room.
Build a Consistent Bedtime Routine
A predictable bedtime routine is one of the most effective tools for any sleep transition. The ideal routine lasts about 30 to 45 minutes and signals to your baby’s brain that sleep is coming. The specific activities matter less than the consistency, but three components show up repeatedly in pediatric guidance: a bath, a calming activity (like reading, singing, or gentle massage), and a feeding.
The order matters slightly. Placing the feeding earlier in the routine rather than last helps avoid the association between eating and falling asleep. A common sequence is bath, feeding, book or song, then into the crib drowsy but awake. “Drowsy but awake” is one of the most repeated phrases in baby sleep advice for good reason: it gives your baby the chance to make the final transition to sleep on their own, which is the core skill that makes the crib work long-term.
Keep the routine identical whether you’re at home, traveling, or having a rough night. The sameness is the point. After a week or two of repetition, most babies begin to visibly relax when the routine starts because they know what’s coming next.
Common Setbacks and What They Mean
Expect the first three to five nights to be the worst. Your baby may cry more, wake more frequently, or take longer to settle. This is normal and doesn’t mean the transition is failing. Most babies show clear improvement within one to two weeks.
If your baby was sleeping well in the bassinet and suddenly struggles in the crib, the most common culprit is the open space. A crib feels vast compared to a snug bassinet. A sleep sack can help recreate that contained feeling. Some parents also temporarily place the crib sheet against their own skin for a few hours before bedtime so it carries a familiar scent.
Illness, teething, or travel can temporarily undo progress. When this happens, do what you need to do to get through it, then return to the crib routine as soon as things settle. Babies are surprisingly adaptable, and a few off nights rarely erase weeks of learning. The consistency you return to matters more than the interruption itself.