# Dates and Calendars

Approximate dates and ranges, dates in the Hebrew, Julian or French Republican calendar, and dates your record only states in words.


Historical records rarely give you a clean date. They say "about 1890", or "before her mother died", or they use a calendar that is not the one on your wall. KleioBase is built to hold what the record actually said rather than forcing you to round it into a modern date and lose the difference.

Every date field in KleioBase works the same way, whether you are editing a person, an event, a fact, or the period covered by a search. This article covers what those fields can express.

For the history rather than the product, which calendar a given parish was on in a given year, feast-day dating, double dating and the rest, see [How to Read Dates in Old Records](/blog/reading-dates-old-records-julian-gregorian-feast-days).

## The parts of a date field

A date field has a **type** dropdown on the left, then the date itself, then a **Calendar** row underneath.

The type decides what kind of claim you are making:

| Type | Means | Example |
| --- | --- | --- |
| Exact | This is the date. | 12 May 1892 |
| About | Approximately, give or take. | About 1890 |
| Estimated | Worked out rather than recorded. | Estimated 1885 |
| Before | No later than this. | Before 1901 |
| After | No earlier than this. | After 1870 |
| From - to | A period with both ends. | From 1903 to 1907 |
| From | A period that started here. | From 1903 |
| To | A period that ended here. | To 1907 |
| Between - and | It happened somewhere in here. | Between 1885 and 1888 |
| Free text | The record's own wording. | "the winter after the fire" |

These are not cosmetic labels. They are the date types the GEDCOM standard defines, so each one survives an export and comes back intact when you import elsewhere.

You can leave parts out. A year on its own is a perfectly good date, and so is a month and a year. Only fill in the day when the record gives you one.

## Dates in another calendar

A date your record gave in the Hebrew, Julian or French Republican calendar is kept and shown in that calendar. It is not quietly converted behind your back. A Hebrew date reads as "15 Tishrei 5649", a Julian one as "12 May 1750 (Julian)".

Where a Gregorian equivalent exists, hover the date to see it, or tap it on a phone, and it appears next to the original.

### Setting or changing the calendar

Every date field you can edit has a **Calendar** dropdown under it. Pick Hebrew, Julian or French Republican and the month list changes to that calendar's own months: Tishrei through Elul, or Vendemiaire through Fructidor.

The one place the dropdown is not offered is the review pane when you are confirming a freshly uploaded record. That screen shows a date field for every person and every event, so a calendar row on each would crowd it. A date already in another calendar still displays and edits correctly there, in its own months; changing which calendar it is waits until the record is in your knowledge base.

### Changing the calendar converts the date

Switching the calendar restates the same day, rather than putting a new label on the old numbers.

- Hebrew "15 Tishrei 5649" to Gregorian gives 20 Sep 1888.
- Julian "12 May 1750" to Gregorian gives 23 May 1750, applying the eleven-day offset that actually separated the two calendars in 1750.

If the date has no day, only the year converts, and the month clears. A Hebrew month spans two Gregorian ones, so naming one of them would state something your record never did.

### The Hebrew calendar

Hebrew dates convert exactly, including the leap-month years. A leap year has both Adar I and Adar II, and KleioBase keeps them apart rather than collapsing both into "Adar", so a date in one does not silently become a date in the other.

Hebrew years run about 3,761 ahead of Gregorian ones, which the year field accounts for. A Hebrew year is not rejected as impossible the way a Gregorian year of 5649 would be.

### The French Republican calendar

French Republican dates convert for the fourteen years the calendar was actually in use. Its era begins on 22 September 1792, which was 1 Vendemiaire of year I, and it was abolished part-way through year XIV, with effect from 1 January 1806. So 9 Thermidor an II converts to 27 July 1794, and 18 Brumaire an VIII to 9 November 1799.

A year outside that span is left as you typed it rather than converted into a date that never existed, because the calendar has no meaning outside the years it was used. Going the other way, a Gregorian date from 1 January 1806 onward is not converted back into it either, even though year XIV nominally ran into the September.

### What the conversion is used for

Primary display is always the source calendar. Behind the scenes, though, KleioBase uses the Gregorian equivalent for anything that has to compare two dates: sorting a timeline, working out someone's age, deciding which siblings are older, judging whether someone might still be living, and choosing which period of history to show alongside their life.

That is the reason it matters. Read literally, a Hebrew year of 5649 sits nearly four thousand years in the future, which would put an ancestor's birth after today and scramble every one of those calculations.

## Dates your record states in words

Not every date is a date. Records say "the winter after the fire", give a day and month with no year, or write something that is not a date at all.

Choose **Free text**, the last option in the type dropdown, and write it exactly as the record has it. GEDCOM has a specific structure for a date stated only in words, so a free-text date survives an export and comes back intact on the way in.

Dates KleioBase cannot read as dates, such as an unusual format from another program or a note someone typed into a date field years ago, come up as free text automatically. You can correct them in place instead of deleting and retyping.

## When you know it happened but not when

Sometimes a record establishes that an event happened without giving any date at all: a marriage is referred to in passing, a death is implied by a widow's remarriage. GEDCOM can record exactly that, an event asserted with no date, and KleioBase handles it for you. The field simply appears empty, and the assertion is preserved as long as you leave it empty. Enter a real date and it replaces the assertion, which is what you want.

There is nothing to configure and nothing to be careful about. It is mentioned here only so you know that an empty-looking date on an imported record is not necessarily lost information.

## Where dates show up

- **Person profiles** carry birth, death, christening and burial dates, plus a date on every event and fact.
- **The timeline** places each event by its date. A date in another calendar is positioned by its Gregorian equivalent so it sits in the right place, while still reading in its own calendar. See [The person timeline](/docs/knowledge-base#the-person-timeline).
- **The family tree** shows a compact year range on each card, and hovering it reveals the full dates in their source calendar. See [Family Tree](/docs/family-tree).
- **Negative evidence** uses a date range for the period a search covered. See [Negative Evidence](/docs/negative-evidence).

## Choosing how dates are displayed

Under **Settings > Account & Preferences** ([/settings/account](/settings/account)) the **Date format** option controls the order dates read in: "12th of May 1892", "May 12th, 1892", or "1892 May 12th". It changes every date display in the app immediately, without a reload. It does not change anything that is stored, and it does not affect your exports.

Canonical: https://kleiobase.com/docs/dates-and-calendars