OpenBitcoin Charts Bitcoin (BTC) Road to 2028 Halving With 95% of Supply Mined

95% of the 21 Million Cap Mined

More than 95% of the 21 million Bitcoin (BTC) supply cap has already been mined, and OpenBitcoin.com, a bitcoin-only explorer and reference site, has launched with a live countdown to the next issuance slowdown set on its front page. Of the fixed 21 million cap, about 20.1 million coins are out in the world. The remainder arrives on a schedule that slows every four years, and the next step, the fifth halving, is due around April 2028. New coins enter circulation only through mining, which pays the block subsidy to whoever assembles each block.

The site puts that countdown next to the lookups a bitcoin user runs in an ordinary day. One search box accepts any address, transaction ID or block number and returns the result on a single page: balance and history for an address, inputs, outputs and fee for a transaction, or every transaction in a block. A Bitcoin (BTC) price converter turns any amount between Bitcoin (BTC), sats and 15 currencies as you type, and a fee tracker shows the current cost to send, when fees are usually cheapest and how large a transaction will be before it goes out. More than fifty guides, calculators and tools sit alongside, from seed phrase backup and self-custody to address poisoning, privacy and inheritance planning, and eleven browser tools run in the page, several fully offline. Three arcade games, Block Builder, Backlog Breaker and The Impossible Slot Machine, turn live network data into play. “Most bitcoin sites make you choose between a serious explorer and a site that explains things,” the OpenBitcoin team said at launch. “We wanted one place where you can check an address, see the price in your own currency, understand what a halving does, and get on with your day. Bitcoin only, no accounts, no noise.”

Counting Down to Block 1,050,000

An earlier milestone lands first: block 1,000,000, expected around April 2027. OpenBitcoin keeps a separate live countdown to block 1,000,000 alongside its halving clock on OpenBitcoin.com. The halving itself is a block-height rule, not a calendar date: every 210,000 blocks, about four years at the ten-minute average, the new coins created with each block are cut in half. Today the subsidy stands at 3.125 Bitcoin (BTC) per block, roughly 450 new coins a day on the 144-block assumption. At block 1,050,000 it falls to 1.5625 BTC, about 225 a day. Actual issuance drifts with block timing, which is why the April 2028 date is an estimate rather than an appointment; Grayscale has likewise framed April 2028 as the working window, not a fixed schedule.

The subsidy is the payout that anchors Bitcoin's proof of work issuance, and it has been halved four times already, from 50 coins per block in 2009 to 3.125 today.

Grayscale noted the 20 millionth bitcoin was mined on March 9, 2026, at block height 939,999, leaving roughly one million against the cap, and the asset manager cautions that mined coins are not the same as coins available to trade. Halvings continue after 2028 until the last fraction is issued around 2140.

On its introduction page, OpenBitcoin states it runs its own Bitcoin Core full node and chain index, pulling block, transaction and address data without third-party APIs and pricing bitcoin at the median of three exchanges. The front page also surfaces the mempool, the queue of unconfirmed transactions, and the next-block fee. The creator introduced the project on Reddit's r/Bitcoin board on August 19, 2026, asking the community for feedback.

The arithmetic is what the countdown dramatizes: issuance is the only tap of new supply in Bitcoin's design, and it halves on a schedule nobody can vote to change. At 3.125 coins a block the network adds roughly 450 coins a day, against demand that now includes corporate treasuries holding coins as a strategic bitcoin reserve. When block 1,050,000 lands, that daily flow drops to about 225 coins. Two caveats apply. The date is keyed to block height, so April 2028 can slide, and coins already mined are not coins on offer. COINOTAG tracks the supply schedule and network data on its running Bitcoin topic hub.