Satoshi Time

Why we count from the Genesis Block

Satoshi Time is a calendar that begins at the exact moment the Bitcoin network started: January 3, 2009, 18:15:05 UTC, stamped into the coinbase of the Genesis Block. Instead of measuring by block height, it measures pure elapsed time from that instant, subdividing the day into units that mirror Bitcoin’s heartbeat while keeping one foot in solar time.

The Epoch

Every clock needs a beginning. Ours is the Genesis Block timestamp: 2009-01-03 18:15:05 UTC. All Satoshi Time is simply the continuous duration since that moment. Leap years are preserved from the Gregorian calendar so that days remain locked to Earth’s rotation.

The Four Units

Anno Satoshi — Complete years elapsed since the Genesis Block.
Year 0 ran from 3 January 2009 to 3 January 2010. We are now in Year 17.

Day — Earth rotations within the current year.
Ranges from 000 to 364 (or 365 in a leap year). This anchors Satoshi Time to sunrise and sunset.

Toshi — Theoretical ten-minute slots per day.
There are 144 toshis in a day (24 × 60 ÷ 10), matching the ideal Bitcoin block interval. A toshi is not necessarily a mined block; it is a temporal slot derived from the protocol’s design target.

Satsec — Decimal subdivision of a toshi.
100 satsecs per toshi, so each unit is roughly 6 seconds. The display shows a whole number and one decimal (e.g., 11.5), giving the clock a smooth, continuous sweep rather than a staccato block tick. This is our nod to the French Revolutionary decimal time system: a radix-100 subdivision that feels natural on a digital face.

Why not just use block height?

Other “Bitcoin calendars” count blocks. That is rigorous, but blocks are irregular—sometimes two minutes, sometimes forty. Satoshi Time chooses continuity. By deriving the clock from the Genesis timestamp rather than from the blockchain itself, we get a smooth, predictable flow: the decimal after the satsec advances evenly, driven by requestAnimationFrame, while still respecting Bitcoin’s 10-minute metronome.

How to read it

A display reading 0017 : 143 : 089 . 45.3 means:

0017 — 17 years since the Genesis Block
143 — the 143rd day of that year
089 — the 89th ten-minute toshi of that day
45.3 — 45.3 satsecs into that toshi

Design

The interface is deliberately austere: Bitcoin orange on dark gray, monospace numerals, minimal chrome. The conventional timezone readout underneath is not a concession—it is a bridge. Satoshi Time does not ask you to abandon meetings or sunrise; it overlays a parallel axis of meaning onto the same planetary rotation.