The answer shouldn't be "well, it depends."
Today it does. It depends on your time zone, on whether daylight saving is in force, and on whether a committee has added a leap second. Leave Earth and it also depends on how deep you sit in a gravity well and how fast you're moving, because relativity makes those clocks run at different rates.
tx is a standard clock for anywhere in our solar system. It counts seconds at the solar system's center of mass, a place that belongs to no planet, from a zero set by the planets themselves. A clock on Earth, on Mars or on a spacecraft converts to the same number, so everyone gets one answer.
Any moment from 1900 to 2100, in tx. Type in either box. Enter your birthday to see your age in tx.
How long familiar things take, in tx. The bars use a log scale: each equal step is ten times longer.
Durations timed by Earth clocks come out about 16 parts per billion longer in tx, because Earth clocks run slow. An Earth day is 86,400.0013 tx.
One SI second, counted at the center of mass of the solar system. It is the same length as the second your phone counts, but kept in a reference frame that belongs to no planet. The count is the number of tx since zero.
UTC follows Earth's rotation, which wobbles, so committees add leap seconds to keep it in step (27 so far). On top of that sit time zones and daylight saving, set by governments and changed often. A tx count never jumps, repeats or depends on where you are.
Clocks run at different rates depending on gravity and speed. A clock on Earth sits in the Sun's gravity well and moves at 30 km/s, so it loses about half a tx a year. Earth's official time scale bakes those Earth conditions in.
The solar system's center of mass is the one reference every world shares. Each clock, on Earth, Mars or a spacecraft, converts to it the same way, and none of them is favored.
Zero is the moment Saturn and Neptune lined up, seen from the solar system's center of mass: the instant the angle between them was smallest. It fell on 11 December 2025 at 23:44:52 TCB. The two planets line up about once every 36 years, and this is the most recent alignment.
A zero should come from nature, not from a nation, a religion or a founding date. An alignment is pure geometry, so anyone with a planetary ephemeris can recompute the moment.
The instant is frozen to a whole tx, so better measurements in the future can refine our knowledge of the alignment without moving zero.
A day is a property of one planet. Earth's is 86.4 ktx, a Mars sol is 88.8 ktx, and a ship has none. Metric prefixes work everywhere: a ktx is about 17 minutes, an Mtx about 11.6 days, a Gtx about 32 years.
No. tx is the shared timestamp; local days and seasons stay local, for sleeping and planting. It works the way software already handles time: store one universal number, show it however the reader likes.
Mars clocks run about half a millisecond a day faster than Earth's, and the simulation behind this page computes that live. A Mars clock applies its own correction and lands on the same tx. Messages carry the tx they were sent at, so the 3 to 22 minutes of light delay is always explicit.
Nobody needs to. The definition is fixed: the SI second, the solar system's center of mass, and a frozen zero. There is no adjustment mechanism, so there is nothing for anyone to decide later.
The physics agrees with the international reference to within about 30 billionths of a tx. The weak link is your device's clock, usually right to a few hundredths of a tx. The desktop version checks against five national time labs.
1 tx ≡ 1 SI second of Barycentric Coordinate Time (TCB)
tx 0 ≡ 2025-12-11 23:44:52 TCB: minimum barycentric Saturn–Neptune separation (0.957°), frozen
Starting the physics engine.
Accuracy is limited by this device's clock, typically a few hundredths of a second.