A small bit of logic will help you work this out without needing software. Look at the power usage of an Android device and you'll see the screen is the main battery drain, followed by the OS being idle. It's only when you run an app for a very long period of time that it shows in the list as being a significant battery drain.
For example if I use my Nexus 4 as a satnav, the screen, network comms and the maps app jump to the top of the list. This is pretty obvious if you think about it.
On your Mac the main battery drain will be the LCD panel and its backlight. On my Lenovo X220 there is a Lenovo battery usage meter that shows current being drawn out the battery. I can adjust the laptop's power usage by several watts simply by adjusting the screen brightness. However running applications makes no noticeable difference.
I don't think Macs can do this (my old 2009 Macbook didn't) but your main power usage will be the screen. If your computer is idle and the CPU temperature is low then the CPU isn't drawing much power which means the software running in it won't be a significant factor.
External USB devices will also drain the battery more. Plug an external USB mouse in and you've just increased the power usage by at least 100mA. Try to sync your iPhone and you're now adding 2A of current drain to the system while it also charges.