Babies climb stairs on all fours at around 12 months, then upright holding a hand or the banister at around 15 to 18 months. They alternate their feet going up between 2 and 3 years. Going down always comes later: backwards first, then on their bottom, and upright only at around 2 years.
These milestones come from Naître et grandir, the reference resource of the Fondation Lucie et André Chagnon, reviewed by an occupational therapist. They describe a stable sequence whose timing varies a great deal from one child to another. This article goes through each stage, what makes it possible and how to support your child without exposing them to falls.
Baby climbing stairs: the stages, month by month
Climbing follows on from motor skills on the floor. A child who crawls already has the arm–leg coordination needed to get up a step. Standing, then walking independently, open the way to the next stage.
Around 12 months: on all fours
Naître et grandir places climbing on all fours at around 12 months. The child puts their hands on the step above, hauls up one knee, then the other. Some children attempt the climb earlier, as soon as they have mastered crawling. The American organisation Pathways.org notes that climbing on all fours can appear as early as the 6 to 9 month period.
Around 15 months: upright, holding a hand
At around 15 months, a child who walks independently starts to climb upright, holding an adult’s hand and the banister. They put both feet on each step before moving on to the next. This stage depends on independent walking: a child who isn’t yet walking alone won’t reach it.
Around 18 months: alone, sideways
At around 18 months, many children climb on their own, holding the banister with both hands, their body turned sideways. Naître et grandir’s development sheets were updated in November 2025. Between 19 and 24 months, they describe a child who goes up and down upright, holding the banister or an adult’s hand. At this stage they put both feet on each step.
Between 2 and 3 years: one foot per step
Between 2½ and 3 years, the child climbs by placing one foot on each step, leaning on the wall or the banister. Going down, they still put both feet on the same step. Fully alternating feet, without the banister, both up and down, only comes at around 4 to 5 years.
Why going down is harder than going up
Going up, the child sees the step in front of them and pushes with their leg. Going down, they have to look down, brake their weight and put their foot on a surface they can’t see well. Balance, leg strength and judging height are all called on at the same time.
It’s the same gap as with climbing furniture: a child can climb up long before they know how to get back down. Our article on the baby who climbs on everything describes this phenomenon and what it means at home.
The three ways of going down, in order
- Backwards, on all fours: this is the safest technique at first, the one Naître et grandir describes at around 12 and 15 months.
- Sitting, on their bottom, facing the drop: this appears at around 18 months.
- Upright, holding the banister with one hand, both feet on each step: between 2 and 3 years.
How can you help your baby go up and down stairs?
Children learn by practising, under supervision, on just a few steps. The tips below follow those of Naître et grandir.
- Start on two or three low steps, at a playground for example, rather than on the stairs at home.
- Always position yourself below your child, whether they’re climbing up or coming down backwards.
- Guide their knee onto the next step, alternating which leg goes first.
- Show them how to turn round at the top to come down backwards, and repeat the movement every time.
- Put a favourite toy at the top or the bottom to give the effort a goal.
- Avoid socks on their own, which slip on wood or tiles: go barefoot or use non-slip slippers.
If your child panics, don’t push it. Naître et grandir recommends talking to a doctor if the fear persists after around two months of practice. They can refer you to an occupational therapist, or check your child’s sight and hearing.
No stairs at home
A child who lives in a single-storey home isn’t behind because of it. Cushions to clamber over, a motor-skills step or a small course on the floor work on the same skills. Our guide to setting up a motor-skills course at home details the possible set-ups by age. A thick baby play mat under these modules cushions the falls, which are inevitable at this age.
Making the stairs safe while they learn
A child who is drawn to the stairs doesn’t yet have any awareness of danger. Until they can go up and down safely on their own, the stairs should be closed off whenever no adult is with them.
- A gate at the top, screwed into the wall: a pressure-fit model can give way under the weight of a child leaning on it.
- A gate at the bottom, which channels their attempts and can be pressure-fit.
- Close supervision at grandparents’ or friends’ homes where the stairs aren’t protected.
Our guide to choosing a baby safety gate explains the fixing points and the standard to check. At the foot of the stairs, as in the play area, a large 150 × 200 play mat softens hard floors during the first falls, without replacing the gate.
At what age should you be concerned?
The ranges are wide. A child who walked late will climb late, without this signalling a problem. Pathways.org advises speaking to a health professional if your child can’t go up or down steps with support by around 2 years.
Context matters too. A child with no stairs at home simply has fewer chances to practise. What should raise concern is rather the loss of a skill already acquired, a clear asymmetry between the two legs or a difficulty that spreads to other movements. To put walking itself in context, our article what age do babies walk sets out the WHO ranges.
Climbing stairs and jumping: two linked milestones
The strength and balance that let a child get up a step also prepare them for jumping. Many children jump down a step, feet together, before they can go down the stairs alternating their feet. Our article on the baby who jumps with feet together details this stage.
Key takeaways
- At around 12 months, babies climb stairs on all fours and come down backwards.
- At around 15 months, they climb upright holding a hand, both feet on each step.
- At around 18 months, they climb alone holding the banister and come down on their bottom.
- Between 2 and 3 years, they climb alternating their feet; alternating on the way down waits until 4 to 5 years.
- A gate screwed in at the top, a gate at the bottom, an adult positioned below: safety is non-negotiable while they learn.
Sources
- Naître et grandir, “Apprendre à monter et à descendre les escaliers”, updated September 2021, scientific review by Marie-Josée Berberi, occupational therapist.
- Naître et grandir, “1 ½ à 2 ans : motricité globale”, updated November 2025.
- Naître et grandir, “2 ½ à 3 ans : motricité globale”, updated November 2025.
- Pathways.org, “When Can Baby Climb Stairs and How Can You Keep Them Safe?”, updated 30 June 2026.
