What is the bitcoin supply schedule?
The pre-programmed pace from zero to 21 million
The Bitcoin supply schedule is the preprogrammed pace at which bitcoin are issued into circulation.
This schedule began at zero when Bitcoin was launched on January 3rd, 2009 and is steadily progressing towards the terminal supply limit of 21 million bitcoin in the year 2140.
When Bitcoin was launched as peer-to-peer electronic cash, there needed to be a way to distribute the bitcoin into circulation. The solution to this challenge was to pair bitcoin distribution with the processing of transactions, in a system commonly called “Bitcoin mining”.
Mining is the process whereby computers compete in successive lottery-style competitions to win the rights to add the next block of transactions to Bitcoin’s blockchain and get paid a bitcoin reward for doing so. That bitcoin reward comes in two parts:
The block subsidy is how bitcoin enters circulation.
The subsidy amount and all other supply-related rules are encoded in the Bitcoin software. The basics of these rules are as follows:
The result of the supply rules is a type of schedule, which sets the quantity and timing of bitcoin’s supply issuance – the “supply schedule.”
Bitcoin’s supply schedule isn’t based on time, but rather on blocks.
The Bitcoin software targets block times of 10 minutes. When more computational power is deployed by miners, blocks can occur faster than 10 minutes, since more computation means increased likelihood of winning the “lottery-style” competition. To compensate, the Bitcoin software automatically re-adjusts the difficulty of mining every 2,016 blocks (called the “difficulty adjustment”) to maintain an average block time of about 10 minutes.
This means the timing of future blocks are projections, which depends on how much or little computational power is deployed by miners over time. Therefore, Bitcoin’s supply schedule doesn’t exist as a calendar with dates set in stone, but as a set of rules that take into account certain variables.
The calculation of the supply can be expressed in terms of a mathematical equation:
Let’s break this equation down into simple terms:
In this formula every 210,000 blocks the cycle (“i”) increments by one, meaning the 1st epoch's maximum block subsidy is set at 50/20 (50), the 2nd is 50/21 (25), the 3rd is 50/22 (12.5), and so on. There are 33 total halving cycles, since the initial cycle starts at 0 and repeats 32 times.
The exact dates of future halvings are projections, since they are based on blocks rather than time and blocks can occur slightly faster or slower than 10 minutes, depending on mining activity. Bitcoin’s supply schedule can be shown in table format.
Year | Epoch | Halving | Block | Block subsidy | Supply at epoch’s end |
---|---|---|---|---|---|
2009 | 1 | 0 | 0 | ₿50 | ₿10500000 |
2012 | 2 | 1 | 210000 | ₿25 | ₿15750000 |
2016 | 3 | 2 | 420000 | ₿12.5 | ₿18375000 |
2020 | 4 | 3 | 630000 | ₿6.25 | ₿19687500 |
2024 | 5 | 4 | 840000 | ₿3.125 | ₿20343750 |
2028 | 6 | 5 | 1050000 | ₿1.5625 | ₿20671875 |
2032 | 7 | 6 | 1260000 | ₿0.78125 | ₿20835937.5 |
2036 | 8 | 7 | 1470000 | ₿0.390625 | ₿20917968.75 |
2040 | 9 | 8 | 1680000 | ₿0.1953125 | ₿20958984.375 |
2044 | 10 | 9 | 1890000 | ₿0.09765625 | ₿20979492.1875 |
2048 | 11 | 10 | 2100000 | ₿0.04882812 | ₿20989746.0927 |
2052 | 12 | 11 | 2310000 | ₿0.02441406 | ₿20994873.0453 |
2056 | 13 | 12 | 2520000 | ₿0.01220703 | ₿20997436.5216 |
2060 | 14 | 13 | 2730000 | ₿0.00610351 | ₿20998718.2587 |
2064 | 15 | 14 | 2940000 | ₿0.00305175 | ₿20999359.1262 |
2068 | 16 | 15 | 3150000 | ₿0.00152587 | ₿20999679.5589 |
2072 | 17 | 16 | 3360000 | ₿0.00076293 | ₿20999839.7742 |
2076 | 18 | 17 | 3570000 | ₿0.00038146 | ₿20999919.8808 |
2080 | 19 | 18 | 3780000 | ₿0.00019073 | ₿20999959.9341 |
2084 | 20 | 19 | 3990000 | ₿0.00009536 | ₿20999979.9597 |
2088 | 21 | 20 | 4200000 | ₿0.00004768 | ₿20999989.9725 |
2092 | 22 | 21 | 4410000 | ₿0.00002384 | ₿20999994.9789 |
2096 | 23 | 22 | 4620000 | ₿0.00001192 | ₿20999997.4821 |
2100 | 24 | 23 | 4830000 | ₿0.00000596 | ₿20999998.7337 |
2104 | 25 | 24 | 5040000 | ₿0.00000298 | ₿20999999.3595 |
2108 | 26 | 25 | 5250000 | ₿0.00000149 | ₿20999999.6724 |
2112 | 27 | 26 | 5460000 | ₿0.00000074 | ₿20999999.8278 |
2116 | 28 | 27 | 5670000 | ₿0.00000037 | ₿20999999.9055 |
2120 | 29 | 28 | 5880000 | ₿0.00000018 | ₿20999999.9433 |
2124 | 30 | 29 | 6090000 | ₿0.00000009 | ₿20999999.9622 |
2128 | 31 | 30 | 6300000 | ₿0.00000004 | ₿20999999.9706 |
2132 | 32 | 31 | 6510000 | ₿0.00000002 | ₿20999999.9748 |
2136 | 33 | 32 | 6720000 | ₿0.00000001 | ₿20999999.9769 |
2140 | 34 | 33 | 6930000 | ₿0 | ₿20999999.9769 |
Some notes on the supply schedule:
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