How To Lower Crib Mattress: Safe, Simple Steps for Parents

If you’re searching for “How To Lower Crib Mattress”, you’re usually trying to solve two problems: keeping your baby safe as they grow and figuring out exactly when and how to adjust the mattress height. This guide walks through the process in clear, practical steps so you can feel confident making the change.

What Does It Mean To Lower a Crib Mattress?

Lowering a crib mattress means adjusting the mattress support platform (or slats, metal frame, or board) to a lower preset height within the crib frame.

Most standard cribs come with multiple mattress height positions. In the highest position, the mattress is closer to the top rail (great for newborns). In the lowest position, it sits much closer to the floor (safer for older, more active babies).

Lowering the mattress does not mean removing parts, stacking items under the crib, or changing the structure. It simply means using the built‑in adjustment system the crib was designed with.

When Should You Lower a Crib Mattress?

Parents often ask “How To Lower Crib Mattress” when their baby starts to move more. Some general checkpoints:

  • When baby starts rolling or scooting – many caregivers lower from the very highest setting to a mid-level.
  • When baby can sit up – this is usually a clear sign to lower the mattress another step.
  • When baby pulls to stand or starts cruising – the mattress should typically be in the lowest position so they can’t climb or topple over the rail.

A simple rule of thumb:
As your baby gains new movement skills, review the mattress height.

How To Lower Crib Mattress: Step‑by‑Step

Always start by reading your crib’s instruction manual, as hardware and exact steps vary. Here is a typical process many cribs follow:

1. Prepare the Space

  • Remove all bedding, toys, bumpers, and accessories from the crib.
  • Move the crib slightly away from the wall so you can access all sides.
  • Make sure you have the right tool ready, often a screwdriver or Allen key.

2. Locate the Mattress Support and Hardware

The mattress usually sits on:

  • A metal spring frame
  • A wooden platform
  • Or metal/wood slats

Look for the screws or bolts that attach this support to the crib’s inside posts. You’ll also see pre‑drilled holes above and below for alternate heights.

3. Support the Mattress Platform

Before loosening any hardware:

  • Keep one hand or your knee under the platform, if possible.
  • Or have a second adult hold it steady while you unscrew.

This prevents the platform from dropping suddenly and protects both the crib and your fingers.

4. Unscrew and Reposition

Working on one corner at a time:

  1. Loosen and remove the screws/bolts holding that corner in place.
  2. Carefully lower the corner to the next lower set of holes.
  3. Reinsert the hardware and tighten it securely.

Repeat for each corner. Make sure you use the same height setting on all four posts so the mattress sits level.

5. Check for Stability and Gaps

Once all corners are lowered and tightened:

  • Press down on the center of the mattress support and each corner to check for wobbling or squeaks.
  • Place the mattress back and make sure:
    • It fits snugly with no large gaps at the edges.
    • The mattress surface is even and flat.
    • There are no loose screws or sharp edges exposed.

How Low Should a Crib Mattress Be?

The “right” height depends on your baby’s stage and the crib’s design:

  • Newborns – often on the highest setting so you can lift them comfortably.
  • Rolling / early sitting – many parents use a middle height.
  • Pulling to stand / cruising – usually the lowest position available.

A useful check:
When your child is standing in the crib, the top rail should be well above their chest, not at their waist level.

Common Questions About Lowering Crib Mattresses

Do all cribs allow you to lower the mattress?

Most modern cribs have at least two height settings, sometimes three or four. If your crib appears fixed, check:

  • The owner’s manual
  • The inside of the crib posts for hidden hardware or adjustment holes

If there truly are no adjustments, follow the crib’s design guidelines and avoid improvising modifications.

Can I use extra pads or add items under the mattress?

It’s generally recommended to keep the sleep surface simple and firm. Adding extra layers under or on top of the mattress can change how it fits, create gaps, or make it too soft. Use the crib exactly as designed with a properly sized crib mattress.

How often should I review the mattress height?

You don’t need a strict schedule. Instead, tie adjustments to milestones:

  • First roll → review height
  • First sit up → review again
  • First pull to stand → usually move to lowest

Whenever your child gains a new skill, ask yourself if they’re closer to climbing or falling, and adjust if needed.

✅ Quick Mattress Takeaways

Key points to understand about “How To Lower Crib Mattress”:

  • Use built‑in settings only – adjust the mattress support using the crib’s existing holes and hardware.
  • Lower as your baby grows – reassess height at rolling, sitting, and standing stages.
  • Work corner by corner – support the platform, move each corner to the same lower hole, and tighten all screws firmly.
  • Check the fit – the mattress should be snug with no large gaps and sit flat on the support.
  • Final position matters – once your child can stand, the mattress is usually safest on the lowest setting.

Taking a few careful minutes to adjust the crib properly keeps your baby’s sleep space aligned with their development and offers added peace of mind as they become more active.