Saturn's 7.5-year cycle with phase-by-phase start and end dates.
Sade Sati is the roughly seven and a half year stretch during which Saturn transits three consecutive signs: the sign before your natal Moon, your Moon's own sign, and the sign after it.
Saturn takes about two and a half years to cross one sign, and three of those is where the name comes from, since sade sati means seven and a half. The count is taken from the Moon sign, not from the Sun sign and not from the ascendant.
The three crossings are reported here as the Rising phase, when Saturn occupies the twelfth from the Moon, the Peak phase, when it occupies the Moon's own sign, and the Setting phase, when it occupies the second. This page prints the start and end date of each phase for the cycle you are in, along with the outer start and end of the whole window.
Within the Peak phase there is a narrower window when Saturn crosses the exact nakshatra pada your natal Moon occupies. A pada is 3 degrees 20 minutes wide, and in direct motion Saturn takes roughly a hundred days to cross it, so that window is short compared to the seven and a half years around it. This page dates it separately.
Retrogression complicates it, and the engine handles that rather than rounding it away. Saturn's retrograde arc is about 6.8 degrees, which is wider than a pada, so Saturn almost always re-enters a pada it has just left. The acute window is therefore measured to Saturn's final exit from the pada rather than its first, and where a retrograde loop straddles the pada that window runs several months longer than the direct-motion figure.
Dhaiya, also called small panoti or chhoti panoti, is Saturn transiting the fourth or the eighth sign from the natal Moon. Each is a single sign crossing of about two and a half years, which is where the name dhaiya comes from. It is not part of Sade Sati and does not extend it; the two are separate transits reported separately, and the page dates whichever one is running.
Saturn's position from the Moon carries distinct traditional names in four more places, and the page names the one in force. The fourth is Ardhashtama Shani, literally half-eighth; the seventh and the tenth are both Kantaka Shani; and the eighth is Ashtama Shani.
The engine grades the tenth and the eighth as harsh and the fourth and seventh as moderate, and it prints the aliases each position is also known by so a reading from another source can be matched to it.
The dates are computed rather than looked up in a table. Saturn's sidereal longitude is scanned forward and backward in coarse five-day steps, which is safe because Saturn moves only about 0.033 degrees a day, and each sign or pada boundary crossing is then refined by bisection to a precise date. The ayanamsha is applied at every step, so the boundaries are sidereal ones.
Retrogression is handled explicitly at every boundary. Saturn can leave a sign and re-enter it, so a naive search for the first crossing can report a retrograde re-entry as the start of the next phase.
The engine takes the first ingress for a start and the last egress for an end, which is why a phase on this page can be a little longer than a flat two and a half years. Saturn's whole synodic cycle is about 378 days and a single retrograde loop about 140, so a return inside those bounds is recognised as a retreat rather than a new period.
This page answers a timing question: whether Saturn is currently in a Sade Sati, Dhaiya or named Kantaka position relative to your birth Moon, and between which dates. That is a transit calculation and it is deterministic. If Saturn is not in any of those positions, the page says so plainly instead of manufacturing a finding.
Because everything is counted from the natal Moon, the only birth detail the result really turns on is the Moon's sign, which changes about every two and a quarter days. A birth time uncertain by hours matters only if the Moon was near a sign boundary that day; the page prints the Moon sign it used so you can check that first.