How can I get the amount of available memory portably across distributions?

The standard files/tools that report memory seem to have different formats on different Linux distributions. For example, on Arch and Ubuntu. * Arch $ free total used free shared buff/cache available Mem: 8169312 3870392 2648348 97884 1650572 4110336 Swap: 16777212 389588 16387624 $ head /proc/meminfo MemTotal: 8169312 kB MemFree: 2625668 kB MemAvailable: 4088520 kB Buffers: 239688 kB Cached: 1224520 kB SwapCached: 17452 kB Active: 4074548 kB Inactive: 1035716 kB Active(anon): 3247948 kB Inactive(anon): 497684 kB * Ubuntu $ free total used free shared buffers cached Mem: 80642828 69076080 11566748 3063796 150688 58358264 -/+ buffers/cache: 10567128 70075700 Swap: 20971516 5828472 15143044 $ head /proc/meminfo MemTotal: 80642828 kB MemFree: 11565936 kB Buffers: 150688 kB Cached: 58358264 kB SwapCached: 2173912 kB Active: 27305364 kB Inactive: 40004480 kB Active(anon): 7584320 kB Inactive(anon): 4280400 kB Active(file): 19721044 kB So, how can I portably (across Linux distros only) and reliably get the amount of memory—excluding swap—that is available for my software to use at a particular time? Presumably that's what's shown as "available" and "MemAvailable" in the output of free and cat /proc/meminfo in Arch but how do I get the same in Ubuntu or another distribution?