Bitcoin's Maximum Supply
Why Bitcoin's hard cap is exactly 20,999,999.9769 ₿ — not 21 million.
Bitcoin's subsidy schedule halves every 210,000 blocks, starting at 50 BTC. Because Bitcoin Core uses integer division (floor) to compute each epoch's subsidy in satoshis, rounding losses accumulate across 33 epochs and the total falls 0.0231 BTC short of 21 million. This is not a bug — it is a direct consequence of how integer arithmetic works, and every full node enforces the same result independently.
The last non-zero subsidy epoch is Epoch 32, paying 1 sat per block. After that, floor(1 / 2) = 0, and no further coins will ever be issued. The last bitcoin will be mined around the year 2140.
The total supply in BTC is the sum over all 33 epochs of the per-block subsidy (in satoshis, floored by integer division) multiplied by 210,000 blocks per epoch, divided by 108 to convert to BTC:
The floor function ⌊⌋ is key. From epoch 10 onward, integer division starts producing rounding losses — for example, floor(50 × 108 / 210) = 4,882,812 sat instead of 4,882,812.5 sat. These sub-satoshi losses accumulate across the remaining epochs, totalling 2,310,000 sat (0.0231 BTC) that will never exist.
Source: Bitcoin Wiki — Controlled supply
| Epoch | Subsidy / block | Sat / block | Blocks | Total issued | % of max | Cumulative |
|---|---|---|---|---|---|---|
| #0 | 50.00000000 ₿ | 5,000,000,000 | 210,000 | 10500000.00000000 ₿ | 50.0000% | 10500000.00000000 ₿ |
| #1 | 25.00000000 ₿ | 2,500,000,000 | 210,000 | 5250000.00000000 ₿ | 25.0000% | 15750000.00000000 ₿ |
| #2 | 12.50000000 ₿ | 1,250,000,000 | 210,000 | 2625000.00000000 ₿ | 12.5000% | 18375000.00000000 ₿ |
| #3 | 6.25000000 ₿ | 625,000,000 | 210,000 | 1312500.00000000 ₿ | 6.2500% | 19687500.00000000 ₿ |
| #4 | 3.12500000 ₿ | 312,500,000 | 210,000 | 656250.00000000 ₿ | 3.1250% | 20343750.00000000 ₿ |
| #5 | 1.56250000 ₿ | 156,250,000 | 210,000 | 328125.00000000 ₿ | 1.5625% | 20671875.00000000 ₿ |
| #6 | 0.78125000 ₿ | 78,125,000 | 210,000 | 164062.50000000 ₿ | 0.7813% | 20835937.50000000 ₿ |
| #7 | 0.39062500 ₿ | 39,062,500 | 210,000 | 82031.25000000 ₿ | 0.3906% | 20917968.75000000 ₿ |
| #8 | 0.19531250 ₿ | 19,531,250 | 210,000 | 41015.62500000 ₿ | 0.1953% | 20958984.37500000 ₿ |
| #9 | 0.09765625 ₿ | 9,765,625 | 210,000 | 20507.81250000 ₿ | 0.0977% | 20979492.18750000 ₿ |
| #10 | 0.04882812 ₿ | 4,882,812 | 210,000 | 10253.90520000 ₿ | 0.0488% | 20989746.09270000 ₿ |
| #11 | 0.02441406 ₿ | 2,441,406 | 210,000 | 5126.95260000 ₿ | 0.0244% | 20994873.04530000 ₿ |
| #12 | 0.01220703 ₿ | 1,220,703 | 210,000 | 2563.47630000 ₿ | 0.0122% | 20997436.52160000 ₿ |
| #13 | 0.00610351 ₿ | 610,351 | 210,000 | 1281.73710000 ₿ | 0.0061% | 20998718.25870000 ₿ |
| #14 | 0.00305175 ₿ | 305,175 | 210,000 | 640.86750000 ₿ | 0.0031% | 20999359.12620000 ₿ |
| #15 | 0.00152587 ₿ | 152,587 | 210,000 | 320.43270000 ₿ | 0.0015% | 20999679.55890000 ₿ |
| #16 | 0.00076293 ₿ | 76,293 | 210,000 | 160.21530000 ₿ | 0.0008% | 20999839.77420000 ₿ |
| #17 | 0.00038146 ₿ | 38,146 | 210,000 | 80.10660000 ₿ | 0.0004% | 20999919.88080000 ₿ |
| #18 | 0.00019073 ₿ | 19,073 | 210,000 | 40.05330000 ₿ | 0.0002% | 20999959.93410000 ₿ |
| #19 | 0.00009536 ₿ | 9,536 | 210,000 | 20.02560000 ₿ | 0.0001% | 20999979.95970000 ₿ |
| #20 | 0.00004768 ₿ | 4,768 | 210,000 | 10.01280000 ₿ | 0.0000% | 20999989.97250000 ₿ |
| #21 | 0.00002384 ₿ | 2,384 | 210,000 | 5.00640000 ₿ | 0.0000% | 20999994.97890000 ₿ |
| #22 | 0.00001192 ₿ | 1,192 | 210,000 | 2.50320000 ₿ | 0.0000% | 20999997.48210000 ₿ |
| #23 | 0.00000596 ₿ | 596 | 210,000 | 1.25160000 ₿ | 0.0000% | 20999998.73370000 ₿ |
| #24 | 0.00000298 ₿ | 298 | 210,000 | 0.62580000 ₿ | 0.0000% | 20999999.35950000 ₿ |
| #25 | 0.00000149 ₿ | 149 | 210,000 | 0.31290000 ₿ | 0.0000% | 20999999.67240000 ₿ |
| #26 | 0.00000074 ₿ | 74 | 210,000 | 0.15540000 ₿ | 0.0000% | 20999999.82780000 ₿ |
| #27 | 0.00000037 ₿ | 37 | 210,000 | 0.07770000 ₿ | 0.0000% | 20999999.90550000 ₿ |
| #28 | 0.00000018 ₿ | 18 | 210,000 | 0.03780000 ₿ | 0.0000% | 20999999.94330000 ₿ |
| #29 | 0.00000009 ₿ | 9 | 210,000 | 0.01890000 ₿ | 0.0000% | 20999999.96220000 ₿ |
| #30 | 0.00000004 ₿ | 4 | 210,000 | 0.00840000 ₿ | 0.0000% | 20999999.97060000 ₿ |
| #31 | 0.00000002 ₿ | 2 | 210,000 | 0.00420000 ₿ | 0.0000% | 20999999.97480000 ₿ |
| #32 | 0.00000001 ₿ | 1 | 210,000 | 0.00210000 ₿ | 0.0000% | 20999999.97690000 ₿ |
| Total (33 epochs) | 20,999,999.97690000 ₿ | 100% | 20,999,999.97690000 ₿ | |||
The theoretical maximum of 20,999,999.9769 ₿ is the sum of all subsidies across every epoch until the last satoshi is mined around 2140. The gross issued supply at the current block height is lower — it only counts subsidies already paid. Additionally, – in known unclaimed subsidies permanently reduce the effective hard cap to –.
- Supply — live issued supply, UTXO set total, and issuance milestones.
- Subsidy Epochs — current epoch progress, halving countdown, and per-era timing.
- Provably Unspendable Bitcoin — Bitcoin whose loss is verifiable on-chain: genesis block, unclaimed subsidies, and OP_RETURN burns.
- Unclaimed Block Subsidies — blocks where the miner left bitcoin on the table permanently.