Today (February 4, 2015) it is worth 80 cents US.
It is $10000000000000000000 for 1 stamp
As of 25 March 2016, 1 US Dollar is worth about 1.37 Singapore Dollars.
Without knowing the date on the stamp, a description and condition, it is impossible to value a stamp.
3 dollars
1c 1 cent
It's worth about $1.99 used depending on condition. It's worth about $1 mint.
1 cent.
The lowest value US stamp was the 1/2 cent. A couple different versions were issued.
Price for this stamp varies from 0.15 cents to 1 dollar according to condition.
20 cents retail. 1 cent as postage.
The H stamp is worth 33 cents. Yes, you can add a 1 cent stamp to cover 34 cents worth of postage.
A 5-cent 1946 Roosevelt stamp is worth about $1, but it depends on the postmark and the design on the stamp. Some postmarks of this stamp could be worth $11 or more.
That depends on many factors. A stamp is worth its face value for use as postage. If you have something that is old and is rare, it could be worth some money. Today's First Class postage stamps are 44 cents.