How many Monero will eventually be mined? Is there a fixed supply?

up vote 16 down vote accepted

The initial number of moneroj in existence will be approximately 18.4 million. However, once that number is reached, a perpetual tail emission of 0.6 XMR per 2 minute block (same rate as the original 0.3 XMR per minute tail subsidy plan) will go into effect.

The block subsidy constants are as follows (modified for clarity):

MONEY_SUPPLY = 2^64 - 1 // The max number of Tacoshis created before tail emission begins
FINAL_SUBSIDY_PER_MINUTE = 0.3 // Tail emission
const int target = version < 2 ? DIFFICULTY_TARGET_V1 : DIFFICULTY_TARGET_V2;
const int target_minutes = target / 60;
const int emission_speed_factor = EMISSION_SPEED_FACTOR_PER_MINUTE - (target_minutes-1);

The 'target' code was implemented when we switched from 1 minute per block to 2 minutes per block.

The tail emission and block subsidy are defined here:

uint64_t base_reward = (MONEY_SUPPLY - already_generated_coins) >> emission_speed_factor;
if (base_reward < FINAL_SUBSIDY_PER_MINUTE*target_minutes)
{
    base_reward = FINAL_SUBSIDY_PER_MINUTE*target_minutes;
}

The tail emission kicks in when the number of Tacoshi in existence (the smallest unit, there are one trillion in each Monero) is between (2^64 - 1) and (2^64 - 1 - .6*1000000000000), or .6XMR worth of Tacoshis away.

The emission schedule is exponentially decaying initially, then switches to linear once the emission reaches a floor of 0.3 monero per minute (pro rata).

While the emission is not known in advance with 100% precision due to block size penalties, an estimation of future block rewards is system B at https://bitcointalk.org/index.php?topic=597878.msg7202538#msg7202538. Note that the graphs on the right at logarithmic.

Due to this tail emission, the number of Monero which will be emitted is infinite, growing slowly over time, by about 158k monero a year (currently increasing at a an instantaneous rate of a bit below 3 million monero a year, for comparison).

An infinite amount although the rate of inflation will slow to a fixed absolute amount so a diminishing % per year

  • 4
    it will take 117 years for the tail emission to double the initial supply. monero looks like it will be mined for a long time. – JohnHanks Jul 19 '16 at 19:29

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