Sleep Regression Calculator
Enter your baby’s birth date to see when the 4, 8, 12 and 18 month sleep regressions and the main growth spurts are likely to happen, which window your baby is in today and how many days until the next one. Premature babies can use adjusted age.
Last updated:
Not born yet? Enter the due date to plan ahead.
3+ weeks early: dates use adjusted age.
How to use the Sleep Regression Calculator
- Enter your baby’s birth date, or the due date if your baby has not arrived yet.
- Add how many weeks early your baby was born, if premature.
- Choose the date you want the status for (today by default).
- Read the timeline: each regression and growth spurt window with its start, end and status.
- Print or download the timeline to keep on the fridge or share with a caregiver.
Sleep regression and growth spurt ages at a glance
The windows below are counted from the birth date (or from the due date for babies born 3 or more weeks early). They are typical ranges reported by pediatric sleep sources and parents; your baby’s timing may differ.
| Phase | Typical window | Usually lasts | Linked to |
|---|---|---|---|
| Growth spurts | 7–10 days, 2–3 weeks, 4–6 weeks | 2–3 days each | Rapid weight gain, cluster feeding |
| Growth spurt | Around 3 months | 2–3 days | Increased appetite |
| 4-month regression | 3–5 months | 2–6 weeks | Sleep cycles maturing, rolling |
| Growth spurt | Around 6 months | 2–3 days | Sitting, starting solids |
| 8-month regression | 8–10 months | 2–6 weeks | Crawling, standing, separation anxiety, 3→2 naps |
| Growth spurt | Around 9 months | 2–3 days | Bigger appetite |
| 12-month regression | 11–13 months | 1–4 weeks | Walking, first words, nap refusal |
| 18-month regression | 17–19 months | 2–6 weeks | Molars, independence, separation anxiety |
| 2-year regression | 23–25 months | 1–4 weeks | Fears, big changes, testing limits |
How the dates are calculated
Each window is a fixed offset from your baby’s starting date. Week-based growth spurts add days (for example 28 to 42 days for the 4–6 week spurt). Month-based windows add calendar months, so the 4-month regression window runs from the date 3 months after birth to the date 5 months after birth. If your baby was born early, the calculator first adds the number of weeks early to the birth date to get the due date and counts from there, which matches how pediatricians track development using adjusted age until about age 2.
Tips for getting through a regression
- Protect the routine. A short, predictable bedtime routine (bath, feed, book, song) helps more than changing everything during a rough patch.
- Watch wake windows. Overtiredness makes regressions worse. Use the baby sleep schedule calculator to check nap timing for your baby’s age.
- Practise new skills in the day. Plenty of floor time for rolling, crawling or standing means less practice at 2 a.m.
- Feed during growth spurts. Extra hunger is normal for a few days; follow your baby’s cues.
- Be consistent at night. Whatever approach you choose, responding the same way each time helps your baby settle faster.
- Know when to call. Fever, breathing trouble, poor feeding, fewer wet diapers or sleep problems that last beyond about 6 weeks are worth a call to your pediatrician.
Frequently asked questions
When does the 4-month sleep regression start?
It usually shows up between about 3 and 5 months of age, most often around 14 to 18 weeks. It happens because a baby’s sleep cycles mature and become lighter, more like an adult’s, so babies wake more easily between cycles.
How long does a sleep regression last?
Most sleep regressions last about 2 to 6 weeks. The 4-month change is permanent in the sense that sleep cycles stay more adult-like, but night waking usually settles once your baby learns to link sleep cycles.
What are the sleep regression ages?
The most commonly described ones are around 4 months, 8 to 10 months, 12 months, 18 months and 2 years. Each tends to line up with a developmental leap such as rolling, crawling, walking, talking or new independence.
Does a premature baby have sleep regressions later?
Usually yes. Sleep development follows adjusted (corrected) age, which is counted from the due date. If your baby was born 3 or more weeks early, enter the number of weeks so the dates shift accordingly.
What is the difference between a growth spurt and a sleep regression?
A growth spurt is a short burst of growth, usually 2 to 3 days, with extra hunger and frequent feeding. A sleep regression is a longer stretch, often weeks, of disrupted sleep linked to brain development and new skills.
Does every baby go through every sleep regression?
No. Sleep regressions are common patterns described by parents and sleep specialists, not medical diagnoses. Some babies sail through some of them, and the timing can vary by several weeks.
How can I help my baby through a sleep regression?
Keep a consistent bedtime routine, watch age-appropriate wake windows, offer extra feeds during growth spurts, practise new skills like rolling during the day and stay consistent with how you respond at night. Always follow safe-sleep guidance.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.