Which Stamps application grownup updated
Find the best combination of stamps for exact postage.


Quick Start

Download Which Stamps. (Requires Java.)

2 Type the denominations of stamps you have available.
3 As you type, Which Stamps calculates the best combination of stamps to use!


When you start Which Stamps, it remembers the denominations you used last time.


There's no Enter button, because Which Stamps works while you type.

What exactly does Which Stamps do?

It shows US domestic postage rates (no big deal, I know), and it also calculates which of your stamps to use to make that postage.


Excellent question. Suppose you have 3 kinds of stamps: 17 cent, 13 cent, and 6 cent. You'd type "17 13 6" at the top of Which Stamps. Then in the "Letters" tab you'd see:

Weight   Cost  Stamps to Use
------   ----  -------------
  card  $0.28  (29 = 17c + 2x6c)
  1 oz  $0.44  2x13c + 3x6c

From this we see that, for a postcard, there is no way to get exactly 28 cents postage. The best combination--one 17c stamp and two 6c stamps--is shown in parentheses.

But for a 1 oz letter, you can make the exact $0.44 postage with two 13c stamps and three 6c stamps. (Amazing. I did not know that.)

Why use a computer? Can't I just pick the biggest stamp that isn't too big, stick it on the envelope, and repeat?

No. The "biggest first" approach does work for making change, but only because each denomination of coin is at least double the next smaller denomination. It doesn't work, for example, on the 44c letter above: 17c + 17c + 6c + Uh oh.

Here's an online "Postage Stamp Calculator" that makes this mistake for you automatically. Just for fun, tell it you have 27c stamps and 14c stamps, and see what it puts on a 28c postcard.

Thank-you Darren Seeman and James Morrissett for helping keep up with USPS rate increases.

I have recently uncovered a sinister conspiracy SO secret that even my drinking buddies, er, I mean, conspiracy-researcher colleagues, won't listen any more. But I continue to tell the world while there is still time!

It started innocently. I needed to mail a six-ounce envelope, and found some stamps in the back of my desk drawer: a roll of 32c stamps, a sheet of 13c stamps, and one 17c stamp. Hmm. Which stamps to use?

At lunch time, I waited in line at the post office. Finally, I reached the front where the clerk was happy to tell me that 6 ounces would cost $1.52. But then I asked if there was any way to make exact postage with the stamps already in my desk. Ha! Now he was not so helpful!

I immediately detected a underlying agenda, so I demanded my rights and made quite a scene. The hidden forces sent out the manager, hoping she could keep their sinister plans from unravelling. She asked me to quiet down, and reminded me that other customers were waiting. But I had figured out their little game!

They assumed I would meekly surrender more postage than necessary, and that's 4 or 5 cents in their pockets!

Now that I use Which Stamps,
-- I don't waste old stamps,
-- I don't pay too much, and
-- I don't have any more unseemly scuffles in the lobby of the post office.

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