For the past few years I've written about how to use USPS postage stamps for business mail without going nuts. My concept centers on finding a very small number of stamps that, singly or in combination, can handle the first few ounces of mail with either one or two stamps.

The normal approach is to buy a base stamp, usually regular first-class, and then add the "extra ounce" stamp as needed. A few years ago the Postal Service changed rates so that the cost of the first three ounces was different for mail in regular envelopes and mail in flats, the latter being a common way of sending business mail.

Last year things got very messy. The USPS did not offer stamps in appropriate denominations, making my little system worthless. I now realize this was a clue that the rates were going to change again very soon. Sure enough, less than a year after last April's increase, a second increase went into effect this January. The good news: this time the USPS quickly responded with exactly the right stamps.

There are two factors that make my little system work. The first is that there are no stamps for the first three ounces of flats - $0.90, $1.10, and $1.30. The second is that those rates can be made up out of the stamps used for envelopes. In 2012, only three different stamps are needed, a record. Not to keep you in suspense, those stamps are 45¢, 65¢, and 85¢. Keeping stamps in the extra ounce rate, 20¢, allows for weights above 5 ounces.

The observant among you will realize that the three stamps listed above represent the current first-class rate for one-, two-, and three-ounce letters. Using one 85¢ plus one 20¢ yields $1.05, the rate for a 3.5-ounce letter. The underlying math is simple - the 65¢ and 85¢ denominations represent the base postage of 45¢ plus additional units of 20¢.

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 20¢ stamps gives you the needed postage.

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.

Stamps

$0.85, Birds of Prey, Glacier National Park
$0.65, Baltimore Checkerspot Butterfly, Dogs at Work, Wedding Cake (reissue)
$0.45, First Class, one ounce (letter, many different stamps)
$0.20, George Washington (Stuart), first class additional ounce