AED pads go in two specific spots: one on the upper right chest, just below the collarbone, and one on the lower left side of the chest, a few inches below the left armpit. Getting this placement right matters more than most people realize. Larger, well-adhered pads with full skin contact can nearly triple the chance that a single shock restores a normal heart rhythm.
Standard Adult Pad Placement
Every AED comes with a diagram printed directly on the pads showing you where to place them. The positions are the same regardless of the AED brand:
- Right pad: Upper right chest, just below the collarbone and to the right of the breastbone.
- Left pad: Lower left side of the chest, a few inches below the left armpit. The top edge of this pad should sit roughly at nipple level or just below it.
This positioning sends the electrical current diagonally across the heart, which gives the shock the best chance of resetting the heart’s rhythm. Press each pad firmly so there are no air pockets or lifted edges. The pads need complete contact with the skin to work properly.
Why Placement and Contact Matter
When pads sit flat against the skin in the correct positions, they reduce the resistance that the electrical current has to push through to reach the heart. Research on pad size and skin contact found that better contact dropped chest resistance significantly, from around 112 ohms with poor contact down to about 72 ohms with full contact. That translated directly into results: a single 200-joule shock succeeded 82% of the time with good pad contact, compared to just 31% with poor contact. A second shock pushed the success rate to 97% in the well-placed group but only 46% in the poorly placed group.
In practical terms, this means a few seconds spent making sure the pads are stuck firmly to bare, dry skin can be the difference between the shock working and not working.
Preparing the Chest
The pads must touch bare skin directly. Before you peel the backing off, you may need to address a few common obstacles.
Clothing and Bras
Cut or pull clothing away from the chest. For bras, a review by the International Liaison Committee on Resuscitation found that it may not always be necessary to fully remove a bra before defibrillation. In animal testing, shocks delivered with pads placed directly over metal underwire still worked 100% of the time with no arcing, burns, or AED malfunction. The key is that both pads must sit on bare skin in the correct positions. If you can achieve that by shifting the bra out of the way, that’s enough. If the bra blocks proper placement, remove it.
Chest Hair
The pads won’t stick well to a very hairy chest, and trapped air under the pad reduces the electrical contact. If chest hair is thick enough to prevent the pads from adhering, you need to clear it. Most AED kits include a disposable razor for exactly this purpose. Shave just the two areas where the pads will go. If no razor is available, some training programs teach a press-and-pull technique: apply the first set of pads, rip them off quickly to pull the hair away, then apply a fresh set of pads to the now-cleared skin.
Moisture and Wet Skin
If the person is lying in a puddle, on snow, or has just been pulled from water, you can still use an AED. You do not need the person to be completely dry. However, you do need to towel off the specific areas where the pads will go. Wet skin prevents the adhesive from gripping, and water droplets between the pad and the skin can reduce the effectiveness of the shock. Wipe each pad site with a towel or clothing before applying.
You cannot use an AED on someone who is still submerged in water. Move them to a dry surface first.
Pad Placement for Children
For children under 8 years old, the standard side-by-side pad positions often don’t work because a small chest doesn’t have room for both pads without them overlapping. Overlapping pads can short-circuit the shock, sending current across the skin surface instead of through the heart.
The recommended alternative is front-and-back placement. One pad goes on the center of the chest, and the other goes on the back, just below the left shoulder blade. This sends the current straight through the heart from front to back. If your AED kit includes pediatric pads (which deliver a lower energy dose), use those for children under 8. If pediatric pads aren’t available, adult pads in the front-and-back position are acceptable.
For children 8 and older, use the standard adult pad positions.
Situations That Require Adjustments
A few scenarios call for modifying the standard placement slightly:
- Implanted pacemaker or defibrillator: You’ll feel a hard lump under the skin, usually below the left collarbone. Place the pad at least one inch away from the device. If the lump is right where the upper right pad would go, shift the pad lower or to the side.
- Medication patches: If a nicotine patch, pain patch, or any adhesive medication sits where a pad needs to go, peel it off, wipe the area clean, then place the pad. Shocking through a medication patch can cause a skin burn and may block some of the electrical current.
- Very large chest: On someone with a large or broad chest, the left pad sometimes ends up too far from the heart. Aim for the pad to sit along the side of the chest at the level of the lower ribs, tucked into the area just below the armpit. You can place the pad slightly under breast tissue if needed to get it into the correct position.
After the Pads Are On
Once both pads are firmly in place, plug the connector cable into the AED if it isn’t already connected. The device will begin analyzing the heart rhythm automatically. Make sure no one is touching the person during analysis or during a shock. The AED will give you voice prompts for every step, including whether a shock is advised and when to resume CPR.
Do not remove the pads once they’re on, even if the person starts breathing again. Leave them in place until emergency medical services arrive. The heart can slip back into a dangerous rhythm, and keeping the pads on allows the AED to detect that immediately and deliver another shock if needed.