Begin by placing the watch, face-down, on a soft surface (such as a towel) that will not scratch the face. Examine the rear of the casing, and locate the tab OR indentation around the edge of the cover. Using an inflexible, dull tool such as a butter knife or flathead screwdriver, gently pry the back cover off by wedging the object into the indentation or against the tab until it yields. If there is not an access tab or indentation, then hold the watch using a vise, position the tool at a point where the rear cover fits into the watch casing, and tap the tool with a rubber mallet. Use caution to avoid damage to the cover or personal injury by errant tools.

Once the battery is visible, determine whether it is being held in place by a bracket. If this is the case, carefully unscrew the bracket using the screwdriver from an eyeglass repair kit.

After the battery has been freed from any additional restraints, turn the watch over and tap it gently to encourage the battery to fall out. Try to allow the battery to fall out of the watch casing, rather than pry it out, because sensitive internal components may be damaged by tinkering tools. Keep track of all washers or gaskets that may be loosened or removed during the process of replacing the battery; it is important that they all be placed back into the watch exactly as they were intended to maintain the watch's function and integrity.

Place the new battery into the watch in the same orientation as the original battery. Press it carefully into place and replace any washers or brackets. Line up the rear cover, paying attention to whether the tab or recess must be lined up with a matching section of the casing. Slide the edge of the cover opposite the indentation or tab into the casing, and then firmly press over the surface of the entire rear cover until it snaps back into place.

Although this may seem like an easy process, there are several types of watches that should not be serviced by anyone other than a professional jeweler. Waterproof watches may be vacuum-sealed, so tampering with the casing will destroy their waterproofing. In addition, high-end watches (which may not even use batteries) should always be brought to a jeweler for any necessary servicing, because meddling with time pieces.