Why Your Houses Differ Between Astrology Sites: A Checklist

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Your Moon is in the 7th house on one site and in the 8th on another. Your Sun has moved from the 10th to the 9th. When two charts for the same birth disagree about houses, it is tempting to conclude that one of them is broken. Usually neither is: the two sources were given slightly different birth data, or they use different settings, or one of them is not showing natal houses at all.

This page is a checklist for finding the cause. Work through it in order. The early checks explain the largest differences and take the least effort; the last ones only matter once everything above them matches. Each item is short and points to the page that holds the details.

The site's side of the comparison. Astrologist.com draws houses in Placidus by default, and in Equal houses from the Ascendant for birthplaces more than 66° north or south, with a notice on the chart; exactly 66° stays Placidus. It does not calculate Whole Sign, Koch, Porphyry, Regiomontanus, Campanus, Alcabitius or any other house system, and there is no setting to change the system. The Astrologist chat works from the house system and house placements of the chart calculated here. This checklist helps you understand a difference; it does not make the site produce another system's houses.

1. The same birth data, including time zone and daylight saving

Houses are the most time-sensitive part of a chart. The Ascendant moves through all twelve signs in about a day, roughly a degree every four minutes on average and much faster or slower depending on the sign rising and the latitude, and every cusp moves with it. So start by checking that both sources have exactly the same:

• date, especially for births close to midnight;
• local clock time, including a.m. and p.m.;
• place, ideally as coordinates, since two towns can share a name;
• time zone and daylight saving in force on the birth date, not today's.

A one-hour slip in daylight saving shifts every cusp by many degrees. A frequent cause is double conversion, where a time already converted to UTC is converted again. Time zones and daylight saving covers these slips, and how accurate your birth time needs to be shows how to test how much a few minutes matter in your chart.

2. The zodiac setting

Astrologist.com uses the Tropical zodiac. Some sites and apps offer a Sidereal zodiac, which places every position roughly 24° earlier in the zodiac for current dates, depending on the Sidereal variant chosen.

A zodiac mismatch does not by itself mean a planet has to change house. With the same quadrant house calculation, the planets and the cusps shift together by the same amount, so a planet can keep its house number while its sign label and the signs on the cusps change. The mismatch still matters. Every sign label changes, so house rulers change, and in sign-based systems such as Whole Sign houses, where each house follows the sign boundaries, a different set of sign labels can put a planet in a different house. If every placement on the other chart is about 24° earlier than on yours, the zodiac setting is the first suspect.

3. The house-system setting

Check which house system each source names. On the free birth chart the line under the wheel says "Placidus houses", or a notice above the wheel says Equal houses are used for a high-latitude birthplace. Other sources may default to a different system or let you choose one in their settings.

If one chart is Placidus and the other is Whole Sign, Equal, Koch or another system, different house numbers are expected, not a fault. House systems explained describes how the families differ, and Placidus vs Whole Sign houses shows one chart in which seven of thirteen bodies change house between the two.

4. The Rising sign, the Ascendant and the true Midheaven

Compare the angles before comparing any house placement:

• Rising sign. If the two sources show different rising signs, go back to items 1 and 2; the house system alone does not change the Rising sign. The free chart names your Rising sign and marks the Ascendant on the wheel, though it does not print the Ascendant degree as a number.
• Ascendant degree. If a source gives the degree, compare it. Matching Ascendants with different cusps point to the house system.
• True Midheaven. In Placidus and other quadrant systems the MC is the 10th cusp. In Whole Sign and Equal houses it is a separate point, so a source can show a 10th house that does not start at the MC without any error. On Astrologist.com's Equal-house charts above 66°, the wheel's "MC" and "IC" labels mark the 10th and 4th cusps, not the true MC and IC; chart angles at high latitudes explains this.

5. Cusp degrees and display precision

When the birth data, zodiac, house system and angles all match, any remaining difference usually involves a planet close to a cusp. Sources show positions at different precision: some round to the nearest minute, others cut the minutes off, and some show seconds or decimals. Two charts can also differ by a fraction of a degree in the cusps themselves. A planet a few minutes of arc from a cusp can then land on different sides of it.

The free chart's planet table cuts minutes off rather than rounding, and it does not list houses: the house is read from the planet's tick on the wheel. How to find your house cusps sets out how to get all twelve cusp degrees from a calculation source, and how to settle a placement that is too close to call at the displayed precision.

6. The high-latitude fallback

For a birthplace more than 66° north or south, Astrologist.com uses Equal houses from the Ascendant and says so on the chart. Another source may still attempt Placidus at that latitude, may use a different fallback system, or may use a different rule for where to switch. Any of these gives different houses for the same birth.

At polar latitudes there is a further caution: the Ascendant itself can move through several signs in minutes, and the site discloses that its current Ascendant routine can, in some polar cases, return the western horizon intersection instead of the eastern one. Treat a polar Rising sign and the Equal cusps built from it as needing independent verification, as chart angles at high latitudes explains.

7. A noon, sunrise or solar chart instead of natal houses

If one source shows houses even though no birth time was entered, it is using a stand-in moment: local noon, sunrise, or a chart that puts the Sun on the Ascendant (solar houses). These are separate reference methods with their own conventions. They do not recover your natal houses, and they can disagree with a natal chart cast for the actual birth time in any house. Noon charts, sunrise charts and solar houses explains each one.

Astrologist.com shows no Rising sign and no houses when the birth time is unknown. It calculates the planets at local noon as an internal reference, but that noon is never presented as the birth moment. A chart without a birth time covers what remains usable.

8. Only then: implementation details and cusp-reading conventions

If everything above matches and a small difference remains, it may come from calculation details: different ephemerides, different methods for the angles, or different handling of edge cases. These usually move cusps by small amounts. Some astrologers and software use special cusp conventions for planets close to a cusp, as noted on how to find your house cusps; Astrologist.com's pages use the exact cusp itself, with each house starting inclusive at its cusp and ending just before the next cusp, and no margin added before a cusp.

A quick way to read the symptoms

When the house system is the cause

If the checks show that the only difference is the house system, both charts are correct for the method each uses. A planet with two possible house numbers keeps its sign, degree and aspects; only the house emphasis differs. Placidus vs Whole Sign houses shows how such a placement can be read without calling either house the real one.

Generate your free birth chart with your exact birth data to compare against. The birth chart calculator guide explains every part of the chart page, the methodology page lists the site's settings, and you can ask the Astrologist about a placement once you know which chart you are reading.

Related articles

• House Systems in Astrology: Placidus, Whole Sign, Equal, Koch and More
• Placidus vs Whole Sign Houses: Why Planets Can Change Houses
• How to Find Your House Cusps
• Birth Time, Time Zones and Daylight Saving
• Chart Angles at High Latitudes
• Noon Charts, Sunrise Charts and Solar Houses
• Birth Chart Calculator Guide