What is Steem Power?
Steem Power or SP is the measure of each user's influence in this Steem community. The more you have it means the more influence you have. More SP also means you add more value in the Steemit. Your worth of upvote are determined through the amount of current SP you have.
Steem Power - Steem Power (abbreviated SP) is a measurement of how much influence a user has in the Steem network. The more Steem Power a user holds, the more they can influence the value of posts and comments. Steem Power is less liquid. If a user wishes to “Power Down” SP, they will receive equal distributions of the STEEM weekly, over a 13 week period.
That quote is according to STEEMIT FAQ SECTIONS
You can check your worth of upvote in https://www.steemnow.com/@yourusername (just change to your own username). Every time you upvote a certain post, using a 100% of your vote weight, your Voting Power or VP are drained by 2%. While that VP will replenish by 20% every 24 hours or by 0.83% per hour. You can adjust your voting weight if you have at least 500 SP. The SP might be permanent or delegated, because both works the same. You can also Power Down your SP, but this will took a long time.
You can increase your SP through Powering UP, just convert your STEEM to SP, the ratio is 1:1. You can also delegate or rent some SP in blocktrades.us. You will pay 139.935 Steem Dollar to rent 1000 SP for 90 days.
You can check the worth of your upvote in this link https://www.steemnow.com/@yourusername
If you have 1000 SP, then each of your upvote will worth $0.26.
Note: The information above might change anytime, because they might vary according to the current rate of the steem and steem dollar in the market. But, this information is highly reliable and can be use for approximation only.