Checking MacBook Pro Maximum Battery Capacity

Usually when the Service Battery Notification ( as per your posting ) it is time to seriously consider having it Evaluated by Find an Apple Authorized Service Provider nearest your location.

There are several reputable Applications that can display the battery capacity - coconut battery is one of many.

Scott-he-him wrote:

If I have the MacBook Pro on a charger it will charge and eventually display 100%. Then if I take it off the charger it will immediately drop to 97%.

Is it safe to assume the maximum capacity is actually 97%? If so that does not seem like a significant reduction to me. Is it?

Lithium-ion batteries are hard to judge since many things inside the battery can interfere with a true reading. Batteries are made up of chemical reactions that can vary due to temperature, voltage, chemical reactions themselves, and even internal "growths" that can affect the functioning and reading of the battery. These items can cause spikes and drops all the time, but occur more often and more severely on older worn out batteries or failing batteries.

Since you are receiving a message about battery capacity being "significantly reduced" combined with the dropping by several percent it may indicate a worn out or even failing battery. I don't know what the design capacity is of each battery. As @P. Phillips mentioned an app like Coconut Battery can give you this information.

Below is my battery information. I do not know what mAh is or if it can be converted into a percentage.

You would need to have the Design Capacity in order to calculate the percentage of the current Full Charge Capacity with the Design Capacity which Coconut Battery will do for you. The "mAh" is just a way of showing the battery capacity (it means milli-amp hours).

P. Phillips wrote:

Usually when the Service Battery Notification ( as per your posting ) it is time to seriously consider having it Evaluated by Find an Apple Authorized Service Provider nearest your location.

Unfortunately "Service Recommended" can mean many things since Apple combines what used to be three separate conditions into this new single "Service Recommended" condition. The old conditions were "Replace Soon" which indicated the battery was below 80% of Design Capacity, "Replace Now" the battery capacity was severely low where most users would not be able to trust it (not sure what % this was), and "Service Battery" indicating macOS has detected a hardware issue with the battery. A third party app such as Coconut battery that you mentioned might still use the older designations, otherwise users will need to rely on the Apple Diagnostics to determine if a hardware fault is detected. I think this was an extremely poor change to make to macOS, but it does sell a lot more of Apple's expensive batteries.

There are several reputable Applications that can display the battery capacity - coconut battery is one of many.

This definitely appears to be the favorite one.