Bitcoin Halving Impact Calculator

Model how a Bitcoin halving changes issuance: daily new BTC, annual issuance, implied inflation rate, and miner revenue from block subsidy. You can optionally include transaction fee revenue.

What a Halving Actually Changes

A Bitcoin “halving” is an event in the Bitcoin protocol that reduces the block subsidy (newly issued BTC per block) by 50%. It occurs every 210,000 blocks. Since Bitcoin targets a block approximately every 10 minutes, halvings happen roughly every four years. The halving schedule is the core mechanism that makes Bitcoin’s supply issuance predictable: new supply decreases over time until it asymptotically approaches a fixed cap (21 million BTC).

People often talk about halving as a price catalyst. Markets are complex; there is no guarantee of any price outcome. But the supply mechanics are objective and are worth understanding even if you ignore price speculation. A halving changes:

• Issuance rate: fewer new BTC created each day.
• Implied inflation: new supply as a percentage of existing supply falls.
• Miner revenue composition: miners earn less from block subsidy and relatively more from transaction fees.

This calculator focuses on those measurable quantities. It does not predict market price. It gives you the arithmetic to answer: “How much less supply enters the market each day after the halving?” and “How big a revenue shock do miners face if price and fees stay constant?”

Block Reward, Issuance, and Inflation

Bitcoin miners earn two forms of revenue per block:

• Block subsidy: newly minted BTC (the part that halves).
• Transaction fees: fees paid by users included in the block.

The block subsidy is what governs new supply. If the subsidy is R BTC per block and there are B blocks per day, then daily issuance is R × B. Annual issuance is daily issuance times 365. The implied annual inflation rate is annual issuance divided by current circulating supply.

Core Formulas

Let:

• R_pre = block subsidy before halving (BTC/block)
• R_post = block subsidy after halving (BTC/block)
• B = blocks per day (≈ 144 if 10‑minute blocks)
• S = current circulating supply (BTC)
• P = BTC price (optional, for USD revenue)
• F = average fees per block (BTC/block, optional)

Daily issuance:

Annual inflation rate (from subsidy issuance):

Miner subsidy revenue per day (in USD) is:

If you include average fees per block, total miner revenue per day in BTC is (R + F) × B. The halving affects only R, not F.

Worked Example

Assume current subsidy is 6.25 BTC/block and the next subsidy is 3.125 BTC/block. Use 144 blocks/day. Suppose circulating supply is 19.7 million BTC. Ignore fees and use a BTC price of $60,000 for revenue illustration.

Pre‑halving daily issuance: 6.25 × 144 = 900 BTC/day.

Post‑halving daily issuance: 3.125 × 144 = 450 BTC/day.

Annual issuance drops from 328,500 BTC/year to 164,250 BTC/year. Implied inflation drops from 328,500 / 19,700,000 ≈ 1.67% to 0.83%.

Miner subsidy revenue drops from 900×$60,000 = $54M/day to 450×$60,000 = $27M/day, a $27M/day reduction unless price or fees change. In practice, miners adapt by improving efficiency, shutting down unprofitable machines, or relying more on fees.

Comparison Table: Pre vs Post Halving

Difficulty Adjustment and Hashrate Dynamics

Bitcoin targets a ~10 minute block interval, but miners’ profitability changes sharply at halving because subsidy revenue drops. If price and fees do not rise enough to compensate, some miners may turn off hardware, reducing network hashrate. When hashrate falls, blocks may temporarily slow down. The protocol responds via the difficulty adjustment, which retargets roughly every 2,016 blocks so that the average block interval returns toward 10 minutes. In other words, a halving can create a short-term profitability shock and then a mechanical stabilization process.

This matters because “blocks per day” is not always exactly 144. In the days after a major hashrate shift, blocks per day can deviate until difficulty adjusts. For long‑term comparisons, 144 is a reasonable average. For short‑term modeling, you can tweak blocks per day to stress‑test outcomes.

Fees and the Long‑Run Security Budget

Over Bitcoin’s lifetime, the block subsidy trends toward zero. That implies a long‑run transition where miners are primarily compensated by transaction fees. Some analysts call this the “security budget” question: if fees are too low, miner revenue could fall, potentially reducing hashrate and making attacks cheaper. Others argue that as Bitcoin’s value and usage grow, fee markets will be sufficient. This calculator helps you visualize how much of miner revenue comes from subsidy versus fees under your assumptions, which is the right way to ground that discussion.

Stock-to-Flow and Supply Shock Intuition

A common macro framing is to compare existing supply (“stock”) to new annual issuance (“flow”). Stock‑to‑flow is:

Stock‑to‑flow = circulating supply / annual issuance. When annual issuance halves, stock‑to‑flow roughly doubles (all else equal). Whether that relationship explains price is controversial, but as a descriptive statistic it captures the idea that Bitcoin becomes scarcer in “new supply” terms over time.

If you want to approximate stock‑to‑flow, use the calculator’s annual issuance outputs and divide your circulating supply by those values. The ratio will jump at halving even if price does nothing.

Limitations and Assumptions

Limitations and Assumptions

This calculator is a supply and revenue arithmetic tool. It assumes:

• Blocks per day is a stable average (real block times vary).
• Circulating supply is entered accurately (the model doesn’t compute it from historical issuance).
• Fee revenue is modeled as a constant average per block if you choose to include it.
• Price effects, demand shifts, and miner behavior are not predicted.

Use the output to understand how issuance and miner incentives change mechanically. If you are analyzing market impact, treat this as a foundational input rather than a price forecasting tool.