Bitcoin Halving Supply Calculator
See the block reward after any number of halvings and how many coins have been issued toward the 21-million cap.
How it works
Reward = initial ÷ 2^halvings · Issued = blocks × initial × 2 × (1 − 0.5^halvings) · Max = blocks × initial × 2
Bitcoin’s issuance falls by half every 210,000 blocks (about four years), so the block reward has stepped down 50 → 25 → 12.5 → 6.25 → 3.125 BTC. Because each era mints exactly half as many new coins as the last, the total issued approaches a fixed ceiling — a geometric series that sums to about 21 million. This calculator applies that logic to any starting reward and era length so you can see the reward and the mined fraction after any number of halvings.
Worked example
With a 50 BTC start and 210,000 blocks per era, after 4 halvings the reward is 50 ÷ 2⁴ = 3.125 BTC. Coins issued = 210,000 × 50 × 2 × (1 − 0.5⁴) ≈ 19.69 million, about 93.75% of the ≈21-million cap.
Sources: Bitcoin (Wikipedia)
Frequently asked questions
Why is Bitcoin capped near 21 million?
Each halving mints half the coins of the previous era. Summing that infinite-but-shrinking series (210,000 × 50 × 2) gives ≈21,000,000 — a mathematical ceiling baked into the issuance schedule, not an arbitrary limit.
When does the last bitcoin get mined?
Because the reward keeps halving, issuance only approaches the cap and effectively ends around the year 2140, when the reward rounds to zero at Bitcoin’s smallest unit (the satoshi).
Does the halving guarantee the price rises?
No. A halving cuts new supply, which is often discussed as bullish, but price depends on demand and countless other factors. Reduced issuance is one input, not a guarantee.
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Educational estimate for crypto/DeFi mechanics — token prices are volatile and yields are not guaranteed. Not financial or tax advice.