Can I get a kundli without the birth time?
You can get most of one, and it is worth knowing exactly how much. A chart is built from two things: where the grahas stood, which depends on the date, and which rashi was rising, which depends on the minute. The first is almost entirely settled by the date alone: Shani moves about two minutes of arc a day, Guru about five, and the Rahu–Ketu axis about three minutes an hour. The second is not settled at all: the lagna crosses all twelve rashis in twenty-four hours, roughly one every two hours, so a chart printed with a lagna in it from a date alone has had an hour invented for it. This page prints the first half and names the second half as missing.
What the date alone genuinely fixes
Every graha whose rashi does not change between the first and the last instant of the local day, which on most dates is seven or eight of the nine. The Sun's rashi and its nakshatra, because the Sun covers about a degree a day. Both nodes. And any yoga or dosha read from those rashis standing against each other rather than against the ascendant. The table on this page marks each graha as held or moving and gives the local clock time of every crossing, found by bisection rather than assumed from an average speed.
What no calculator can supply
The lagna, and therefore every bhava, every bhava lord, and everything counted from the ascendant (the Arudha padas, the ascendant reading of Mangal dosha, the house-based half of the strength calculations). Also the exact dates of the Vimshottari periods, since the balance at birth is measured in degrees of the Moon inside its nakshatra and the Moon covers a full nakshatra in about a day. A page that hands you these from a date has chosen an hour on your behalf without saying so.
What changes during the day, and when?
Three things, and the page times all three. The Moon moves about thirteen degrees a day, so it changes nakshatra roughly once a day, changes pada roughly every six hours, and changes rashi every two and a quarter days, so on most dates the rashi holds and on some it does not, and which of those is true for your date is computed rather than assumed. The lagna changes about every two hours, and the page lists every window with its local start and end. And any faster graha sitting near a rashi boundary, usually Budha or the Moon, crosses it at a specific minute, which is given.
The lagna timetable
The ascendant is scanned every four minutes across the whole local day and each change of rashi is recorded, which gives twelve or thirteen windows depending on where the day boundary falls inside one of them. The windows are not equal: a rashi of short ascension can rise in under ninety minutes while one of long ascension takes over two and a half hours at northern latitudes, which is why a rough guess at the hour is a rough guess at the lagna and not a near miss.
The Moon's path through the day
Every nakshatra and pada window the Moon passes through is listed with its local clock times, and each carries the namkaran syllable of that pada. Where the whole day sits inside one nakshatra, the janma nakshatra is settled and only the pada is open. Where the Moon crosses into the next nakshatra, the ruling graha changes with it, and that is the graha whose mahadasha runs from birth, so the crossing matters far beyond the name.
How does the birth time change the dasha?
It changes the balance, and sometimes the lord. The Vimshottari sequence begins from the nakshatra the Moon occupied, and the portion of the first mahadasha already spent at birth is the portion of that nakshatra the Moon had already crossed. A nakshatra is 13°20' and the Moon covers it in about a day, so an hour of birth-time uncertainty is roughly four per cent of the first mahadasha, which on a sixteen-year Guru mahadasha is about seven months, and that seven months shifts every dasha boundary for the rest of the life. If the Moon crossed into the next nakshatra during the day, the starting lord itself is undecided, and the page says so in those words.
When the lord is the same either way
Most dates. The Moon stays inside one nakshatra for about twenty-four hours, so on a typical date the ruling graha at sunrise and at the end of the day is the same graha and the first mahadasha is known. What is not known is when it ends: the result states the balance at sunrise and the balance at the day's end, and the gap between them is the size of the error in every subsequent date. The sequence is right; the calendar attached to it is not.
When the lord is genuinely open
When the Moon crossed a nakshatra boundary during the day, a birth before the crossing and a birth after it start two different mahadashas under two different grahas. That is not a small difference of dates, it is a different sequence entirely, and no amount of care with the rest of the chart repairs it. Narrowing the hour to one side of that crossing is the single most valuable thing a family record can do.
What is birth time rectification?
It is the classical procedure for recovering an unknown hour from events that have already happened, and every school of Jyotish has one. The common method works backwards: take dated events a person can vouch for (a marriage, a move, an illness, a change of work) and test candidate birth times to find the one whose dasha and antardasha periods, and whose transits over the resulting lagna, line up with those dates. Parashari practice adds the Nadi Amsa and the tools of the Prashna chart, and the Krishnamurti tradition uses a separate ruling-planets method. None of it is arithmetic a calculator can do unaided: rectification is an astrologer's judgement against a person's own history, and the texts treat it that way.
What rectification asks of you
Dated events, and an honest window. An astrologer working from "sometime in the morning" and four life events can usually narrow an hour to a few minutes; one working from "probably 1985" and no events cannot work at all. The birth record, the hospital note, the entry in a family bible or a janma patri written at the namkaran are all better starting points than a memory, and are worth looking for before paying for anything.
What to do while the hour is unknown
Read the part of the chart that is fixed, which this page isolates, and leave the rest alone rather than reading a chart built on an assumed hour. The chandra rashi, where it is settled, carries a great deal of the tradition's reading on its own: gochar, the Moon-based dasha, and the nakshatra-based classifications are all read from it. The naam rashi is used the same way, as a stand-in the tradition itself acknowledges as a stand-in.
Is a noon chart or a sunrise chart good enough?
For the grahas, usually. For the lagna, no, and the trouble is that a sunrise chart does not look like a chart with a missing piece, it looks like a chart. A Surya lagna chart, which puts the Sun's rashi on the first house, is the traditional answer and is honest about what it is doing: it reads the houses from the Sun because the ascendant is unavailable. A Chandra lagna chart does the same from the Moon and is the more common choice in practice, since most of the tradition's day-to-day reading is Moon-based anyway. Both are declared substitutions. A sunrise chart presented as a birth chart is an undeclared one, which is the only thing wrong with it.
Reading from the Moon instead
Chandra lagna is what a panchang-based reading uses by default, and it needs only the Moon's rashi, which this page will tell you is fixed on most dates. Gochar is read from it, the Vimshottari dasha is calculated from the Moon, and the nakshatra classifications a matching uses come from it. Where the Moon's rashi is fixed for your date, a very large part of the tradition's ordinary reading is available without the hour at all.
Why we do not print a lagna anyway
Because a rashi in the first house is not a small detail that can be corrected later: it decides which graha lords which bhava, which reorders every house-based statement in the chart. Getting the hour wrong by two hours does not make the reading slightly wrong, it makes a different reading. The page lists all twelve or thirteen lagna windows instead, so you can see the whole range the unknown hour covers.
What can I still calculate with a date and place?
More than most people expect. The chandra rashi on any date the Moon does not change rashi, and this page says which kind of date yours is. The janma nakshatra whenever the Moon stays inside one, with only the pada left open. Sade Sati and the Shani dhaiya, since both are read from the Moon's rashi against Shani's transit. Kaal Sarp, which is read from the Rahu–Ketu axis against the other grahas. And the whole panchang of the day, which is a property of the date and place rather than of the hour. What needs the hour is the house layer, and only the house layer.
Tools that work from the date
The Moon sign calculator asks for a time but publishes the degree, so a date whose Moon sits well inside a rashi is safe at any hour of it. Sade Sati and Kaal Sarp both read from positions that barely move in a day. The naam rashi, read from the first syllable of a name, needs no birth details at all and is the tradition's own acknowledged fallback when the Moon is unavailable.
Tools that will mislead you
Anything that returns houses. The lagna calculator, the Arudha padas and the house-based reading of Mangal dosha all count from the ascendant, and an ascendant from a guessed hour is a guess carried into every statement they make. Run them once the hour is rectified, not before. If you must run them now, run them at both ends of the window and treat only what agrees as usable.
How accurate does the birth time need to be?
For the lagna, to within about ten minutes if you want the bhava cusps to hold, and to within about two hours if you only need the right rashi rising, though near the edge of a lagna window even two minutes decides it. For the Moon's pada, to within an hour or so. For the Moon's rashi, to within several hours on most dates. For the slow grahas, the date is enough and the hour is irrelevant. This is why "the time is roughly right" is not one statement but four different ones, and why the page separates them: the same hour of uncertainty is fatal to the lagna, awkward for the dasha dates and harmless to Shani.
Rounded times and remembered times
A time recorded as a round hour was usually rounded, and the safe reading is to treat it as a thirty-minute window either side. A time remembered decades later by a relative is not a record and should be treated as a two-hour window at best. Running this page for the date will tell you whether that window even matters: on a date where the Moon and the fast grahas are all mid-rashi, it changes nothing but the lagna.
Time zones and the older records
A birth before a time-zone change, or in a place whose administrative zone has moved, can carry an hour of error in the record itself rather than in the memory. Indian records from before 1955 are the common case, when local mean time was still in ordinary use alongside IST in parts of the country. The computation on this page uses the zone the place has on the date given, and the zone name is printed with the result so it can be checked.
What does this page compute, exactly?
The chart is built at four instants of your local day (sunrise, local noon, sunset and the last minute before midnight), and the first and last are compared. A graha holding one rashi across both is reported as fixed for the day. One that has moved is reported with the clock time of its crossing, found by bisecting the sign boundary to within a second rather than interpolated from an average speed. The lagna is scanned every four minutes across the whole day; the Moon is sampled every twenty minutes and each nakshatra and pada edge is then bisected the same way. Positions are nirayana with the Lahiri (Chitrapaksha) ayanamsha, and where houses are mentioned they are whole-sign; a Bhava Chalit or Placidus reading would place the cusps differently.
Why sunrise and not midnight
Because the Hindu day begins at sunrise, and a panchang quoting a nakshatra for a date means the nakshatra running at that sunrise. Comparing sunrise with the end of the civil day covers both conventions at once: the fixed list is what holds across the wider of the two spans, so it stays true whichever day boundary your family record was written against.
Why the crossing times are bisected
Because a graha near a rashi boundary does not move at its average speed. The Moon's daily motion varies between about eleven and fifteen degrees depending on where it is in its orbit, and Budha near a station can take days to cross a degree. Interpolating from a mean rate can put a crossing an hour or more out, which is the difference between the right rashi and the wrong one for someone born near it.
How this is calculated
Nirayana rashis with the Lahiri (Chitrapaksha) ayanamsha and whole-sign bhavas, computed to arc-second accuracy. Sunrise and sunset are the ones almanacs show, the Sun's upper edge with refraction, so the daily windows agree with the calendars you compare them with. More on our method.