Bitcoin Block Height to Date Estimator (and Back)

Bitcoin Block Height ↔ Date Estimator

Timelocks, halvings, soft-fork activations and some inheritance setups are defined by block height, not by calendar date. This estimator converts a Bitcoin block height into an expected UTC date and a date into an expected height, using the 10-minute target from a reference block, and shows how uncertain the answer is.

How the estimate works

The difficulty adjustment every 2,016 blocks keeps the average block interval near 600 seconds. From a reference block with a known time, a block n blocks later is expected at reference time + n × 600 seconds. The default reference is block 840,000, the fourth halving, mined on 20 April 2024 at 00:09:27 UTC. You can replace it with any recent block from an explorer to make short-range estimates more accurate.

expected time   = reference time + (height − reference height) × 600 s
expected height = reference height + (time − reference time) ÷ 600 s
spread (±1σ)    ≈ √|n| × 600 s

Why the answer is approximate

Block discovery is random: the time to the next block follows an exponential distribution with a 10-minute mean. Over many blocks the errors partly cancel, which is where the √n spread comes from: about ±7.5 hours over one difficulty period of 2,016 blocks, about ±3 days over 200,000 blocks. Long-term drift adds more: while hashrate grows, blocks arrive a little faster than 10 minutes until the next adjustment, which is why the fourth halving came earlier than a naive estimate from genesis would suggest.

Halvings

The block subsidy halves every 210,000 blocks: 50 BTC at genesis, 3.125 BTC since block 840,000 and 1.5625 BTC from block 1,050,000. The estimator shows the next halving height after the block you enter and the subsidy after it.

Frequently asked questions

+When is the next Bitcoin halving?

At block 1,050,000. With the 10-minute target from block 840,000 that is around April 2028; recent blocks give a more precise estimate.

+How accurate is a block height date?

For a few hundred blocks ahead, within hours. For years ahead, within days, plus any systematic drift from hashrate growth.

+What is the current block height?

Any block explorer or your node shows it. Enter it with its time as the reference for the best estimate.

+Why do timelocks use block heights?

Heights are part of consensus and cannot be faked by a single miner's clock. Time-based locks use the median time of past blocks for the same reason.

Calculations run entirely in your browser; nothing you type is sent to KOT.CASH. Results are estimates for information only and are not financial, tax or legal advice.