I don't know where I got this list but if you don't have access to a Milkbone canister but do have scales this might come in handy:

Rough number of empty primed brass per pound; May vary due to brand of brass. Not an absolute.

115 9mm
100 40 S&W or 357 sig
80 45 acp
100 38 spl
90 357 mag
145 380 auto
168 32 auto
75 .223 Remington (or any derivative such as 222 etc)
40 .308 Winchester (or any derivative such as 243 etc)
36 .30-06 Sprgfld (or any derivative such as 270 etc)

Approx. Weight per 1000 cases:
9mm, 59.46gr/ea, 117.7cases/#, 8.5#/1000

38spl, 68.06gr/ea, 102.8cases/#, 9.7#/1000

40s&w, 70.1gr/ea, 99.9cases/#, 10#/1000

.357mag, 78.3gr/ea, 89.4cases/#, 11.2#/1000

.45acp, 89.58gr/ea, 78.1cases/#, 12.8#/1000

.223, 95.28gr/ea , 73.5cases/#, 13.6#/1000

.44mag, 114.38gr/ea, 61.2cases/#, 16.3#/1000

50bmg, 865.26gr/ea, 8.1cases/#, 123.5#/1000

All weights are uncleaned fired cases with the primer remaining.

Individual case weights were derived using an average of mixed brass weights (except 50bmg)

So, if you picked up 8#s of 45 brass: 8# X 78.1cases/# = 625 cases+/-

If you use 1gal ziploc freezer bags to store your brass, each (full) bag contains:

9mm, 15.6#, 1836cases
40s&w, 12.2#, 1219cases
45acp, 11.4#, 890cases
223, 11#, 809cases

If you use 5gal buckets each full one will have

9MM = 8500-9000 pieces
.40 S&W = 7000-7500 pieces
.45 ACP = 3800-4000 pieces

A few more CASES per POUND:

.380: 145
.357 Sig: 96
.45 GAP: 86
.32: 168
10mm: 96
FN 5.7: 124
.25 acp: 260
.30 Luger: 120
.38 S&W: 120
.38 Super: 104
9mm MAK: 124
.45 Colt: 60
.30-M1: 100
.308: 40
.30-06: 35
7.62x39: 54
.50 AE: 48
.30-30: 52