Private astrology calculator

Cast the chart of a relationship

A composite chart blends two birth charts into one — either by midpoints between each pair of planets or, in the Davison method, by casting a real chart for the midpoint in time and space; enter both birth cities and times and both are computed here, offline.

Two birth moments

Enter both birth details

Pick each birthplace — the zone follows.

Person A

Birth place

An offline city list. Nothing goes online.

Set the place manually

Coordinates are optional here. A recognized IANA time zone (for example Europe/Warsaw) is enough to apply the correct historical offset, but the rising sign and houses need latitude and longitude too.

Birth date
Birth time

Pick a city to apply its time zone

Person B

Birth place

An offline city list. Nothing goes online.

Set the place manually

Coordinates are optional here. A recognized IANA time zone (for example Europe/Warsaw) is enough to apply the correct historical offset, but the rising sign and houses need latitude and longitude too.

Birth date
Birth time

Pick a city to apply its time zone

Both birth moments and coordinates stay in this tab.

Ready when both people's details are entered.

The Sky Over Yours, TodayWhich planets are touching your chart now — and when each contact is exact.See today's sky →carries date · time · cityThe Sun's ReturnYour solar return for any year, cast wherever you will be.Cast your return →carries date · time · cityThe Hours of the PlanetsSunrise to sunset in twelve unequal hours, each ruled in turn.See this hour →carries the date · city

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Birth chart calculatorCalculate Sun, Moon, rising sign and planetary placements from one private form.Calculate a chart →Moon sign calculatorFind the Moon sign and exact zodiac degree for a birth moment.Find your Moon →Rising sign calculatorFind the Ascendant from an exact time and birthplace city.Find your rising sign →Big Three calculatorSun, Moon and rising sign in one private result.Find your Big Three →Synastry chart calculatorCompare two birth charts — every cross-aspect, house overlay and reading between them.Compare two charts →Composite chart calculatorBlend two birth charts into one — a midpoint composite or a real Davison chart for the pairing.Cast the composite →Transit chart calculatorSee which planets are contacting your birth chart today, and step through nearby dates.See today's transits →Solar return chart calculatorCast your solar or lunar return for any year — return-to-natal aspects and house placements.Cast your return →Planetary hours calculatorSee which planet rules this hour, day or night, for any city, and every hour around it.See today's hours →

Direct answer

What you need

Both people's birth dates and times are required. The midpoint composite needs nothing more; the Davison chart's own houses and angles need both birth cities too, each applying its zone and coordinates on its own.

Nothing is uploaded or placed in the URL. A cast is kept only in this tab's own memory — long enough for "Read next" — until you close the tab.

Method & limits

Astronomy first, symbolism second.

The midpoint composite averages each planet's zodiac longitude directly and never casts houses or angles. The Davison chart is a real chart instead, cast for the mean instant of both birth times at the great-circle midpoint of both birthplaces — its own houses and angles are computed the same way as any other chart on this site, once both birthplaces are known.

Frequently asked questions

What is a composite chart?

A composite chart works out the midpoint between two people's charts, one planet at a time — the point exactly between where each planet stood in one chart and where it stood in the other — producing a single, symbolic chart of the pairing rather than of either person.

What is a Davison chart, and how is it different from a midpoint composite?

A Davison chart is a real chart cast for the mean instant of two birth moments, at the great-circle midpoint of two birthplaces — a chart with its own houses and angles, computed the same way as any other chart on this site. A midpoint composite instead averages each planet's zodiac degree directly and never casts angles or houses at all.

Why does the Davison chart need both birthplaces, but the composite does not?

The midpoint composite only needs each planet's zodiac position, which depends on time rather than place, so it can be worked out from two birth times alone. The Davison chart casts a real chart at a real location — the great-circle midpoint between the two birthplaces — so its own houses and angles need both.

What if one person's birth time is unknown?

Leaving one person's birth time unknown still works out both charts, using a neutral midday placeholder for that birth. The midpoint composite has no houses or angles either way; the Davison chart needs a verified birth time on both sides, not only both birthplaces, before it will cast its own houses and angles — otherwise it shows the midpoint instant and planet positions alone.

Which orbs does this composite chart use?

Both the midpoint composite and the Davison chart use the same orb set as every other chart on this site: eight degrees for a conjunction or opposition, six for a square or trine, and five for a sextile. In each aspect list here, anything wider than three degrees is folded out of view by default.

Is either person's birth information sent anywhere?

No. Both charts are calculated entirely in your browser, using the same local astronomy library and offline city list as every other calculator on this site. Neither birth date, time nor place is uploaded, stored on a server, or placed in the page URL — there is no link that could ever reveal either person's birth details.