Historically, the U.S. Postal Service has done a reasonably good job setting denominations for stamps. A good set of denominations is important if you use stamps for more than just first class mail and want to minimize the number of stamps used.

The USPS' recent record is not as good, particularly for business postage. For example, the base rate for a one-ounce flat (an envelope larger than 6-1/8" x 11-1/2") is 88¢ but there is no single stamp at that rate. Even though most business mail is from 1 to 3 or 4 ounces, there are no exact-rate stamps for those weights, either. A simple way to handle multiple ounces is to use a base stamp and then add extra postage (currently 17¢ per ounce), but without the base stamp this doesn't work.

That made me wonder if there was some combination of existing stamps that was efficient and practical. Not only did I find those combinations, I found that with just four different stamps you can handle regular and business postage. Not to keep you in suspense, those stamps are 44¢, 61¢, 78¢, and 17¢.

The observant among you will realize that the first three stamps listed above represent the current first-class rate for one-, two-, and three-ounce letters. Using one 78¢ plus one 17¢ yields $1.05, the rate for a 3.5-ounce letter. The underlying math is simple - the 61¢ and 78¢ demoninations represent the base postage of 44¢ plus additional units of 17¢.

For flats, the following table shows that just two stamps will provide the correct postage for the first five ounces:

Beyond 5 ounces (and up to 13) adding 17¢ stamps gives you the needed postage.

Now many of you will no doubt shrug and say "Who cares? I use a postage meter!" or "I use electronic postage!" I say great! But what if the volume of mail does not justify the expense of such methods? Stamps are cheap and relatively fast to apply, especially the self-adhesives. There are thousands of very small businesses who count every penny and won't pay the premium for postage meters or digital postage. Most of my clients fall into that category.

Now for the bad news. Postage rates change very quickly these days. Rarely a year goes by in which the rates do not change. Thus my clever system could be rendered completely defunct by a change of just one cent in either the first ounce or additional ounce rates.

Until then, just four stamps could make your mailing life easier.

Update, April 3, 2011 - USPS rates will increase on April 17, 2011. In an unusual move, the base rates for one ounce letters and flats will not change but additional ounces will jump nearly 18% from 17¢, a rate in place since 2007, to 20¢. That makes the four stamp denominations of interest 20¢, 44¢, 64¢, and 84¢.

Stamps

$0.78, Mary Lasker, Distinguished Americans Series
$0.61, Richard Wright, Literary Arts Series & Wedding Cake, special edition
$0.44, First Class, one ounce (letter) (23 different stamps)
$0.17, Bighorn Sheep, first class additional ounce

Stamps after April 17, 2011 Increase

$0.84, none available
$0.64, Monarch Butterfly
$0.44, many available
$0.20, First Class additional ounce - none available