Controlled Supply


“A fixed money supply, or a supply altered only in accord with objective and calculable criteria, is a necessary condition to a meaningful just price of money.”

Fr. Bernard W. Dempsey, S.J. (1903-1960)

In a centralized economy, currency is issued by a central bank at a rate that is supposed to match the growth of the amount of goods that are exchanged so that these goods can be traded with stable prices. The monetary base is controlled by a central bank. In the United States, the Fed increases the monetary base by issuing currency, increasing the amount banks have on reserve or by a process called Quantitative Easing.

In a fully decentralized monetary system, there is no central authority that regulates the monetary base. Instead, currency is created by the nodes of a peer-to-peer network.

The Bitcoin generation algorithm defines, in advance, how currency will be created and at what rate. Any currency that is generated by a malicious user that does not follow the rules will be rejected by the network and thus is worthless.

Currency with Finite Supply

Block reward halving
Controlled supply

Bitcoins are created each time a user discovers a new block. The rate of block creation is adjusted every 2016 blocks to aim for a constant two week adjustment period (equivalent to 6 per hour.)

The number of bitcoins generated per block is set to decrease geometrically, with a 50% reduction every 210,000 blocks, or approximately four years. The result is that the number of bitcoins in existence will not exceed slightly less than 21 million.

Speculated justifications for the unintuitive value “21 million” are that it matches a 4-year reward halving schedule; or the ultimate total number of Satoshis that will be mined is close to the maximum capacity of a 64-bit floating point number. Satoshi has never really justified or explained many of these constants.

Cumulated bitcoin supply

This decreasing-supply algorithm was chosen because it approximates the rate at which commodities like gold are mined. Users who use their computers to perform calculations to try and discover a block are thus called Miners.

Motivation Formula

Motivation = (Expectancy X Value) / (Impulsiveness X Delay)
  • Expectancy : How likely you feel you’ll succeed
  • Value : What you’ll gain from succeeding
  • Impulsiveness : Your natural inclination to put things off
  • Delay : How much time you have to complete the task

Add it up, and the result is your current level of motivation. 

The less confident you are, the less exciting the outcome, the longer you have to get it done … the more likely you are to put it off.