A house system is the rule that divides the 360-degree sky into twelve houses around a birth chart. The Vedika API exposes house-system selection as a request parameter, so the same birth data can return whole-sign houses for a Vedic reading, Placidus cusps for a Western chart, or Sripati (Bhava Chalit) bhavas for a North-Indian style kundli — without recomputing the underlying ephemeris. This guide explains how each system divides the sky, when to use which, and the exact endpoint shapes for requesting them.
What a house system actually decides
Two charts can place every planet at the identical zodiacal longitude and still disagree about which house a planet falls in. That disagreement is entirely a function of the house system: planetary positions come from the ephemeris, while house cusps come from a geometric rule applied to the local horizon, the meridian, and the latitude of birth.
The consequence is practical: a planet at 8° Scorpio might be read as a 7th-house influence under one system and a 6th-house influence under another. Since house placement drives most interpretive output — career from the 10th, marriage from the 7th, gains from the 11th — the house system is not a cosmetic toggle. It changes the reading, so picking it deliberately and recording which one you used is part of building a defensible astrology product.
The two inputs every house system shares
- The Ascendant (Lagna) — the zodiac degree rising on the eastern horizon at the moment and place of birth.
- The Midheaven (MC) — the zodiac degree culminating on the local meridian.
Every system below starts from these two points and differs in how it fills in the ten cusps between them.
The three house systems you will use most
Whole-sign houses
The oldest documented system and the default for most Vedic (Jyotish) work. The sign containing the Ascendant becomes the entire 1st house; the next sign is the entire 2nd house, and so on. House boundaries coincide exactly with sign boundaries, so a house is always 30 degrees wide and a planet's house equals the offset between its sign and the rising sign.
Whole-sign placement underpins the bhava logic in Brihat Parashara Hora Shastra and Phaladeepika, which is why it is the natural pairing for Vimshottari dasha, yoga detection, and divisional-chart analysis. It is also the most stable system at extreme latitudes, where degree-based systems become unreliable.
Placidus
The most widely used system in modern Western astrology. Placidus divides the diurnal and nocturnal arcs that each degree travels by time, producing house cusps of unequal zodiacal width that shift with latitude. Because it is time-based, Placidus is sensitive to birth time and to the geographic latitude — the same minute of birth at two different latitudes yields different intermediate cusps.
Placidus is the system assumed by most Western interpretive material descending from the Ptolemaic tradition (Ptolemy's Tetrabiblos establishes the angular framework that later table-makers built on). It is the right choice when your output is a tropical Western reading and your users expect cusp-based house rulerships. Note that Placidus is mathematically undefined inside the polar circles; robust software falls back to whole-sign or a comparable system above roughly 66° latitude.
Sripati (Bhava Chalit)
The Indian degree-based system, also called the Bhava Chalit chart. Sripati treats the Ascendant degree as the midpoint of the 1st house rather than its start, then derives bhava cusps from the Ascendant and MC. This is why a planet can sit in one rasi (sign) but a different bhava (house) — a distinction North-Indian practitioners check before finalising a reading.
Sripati matters because a whole-sign chart and a Bhava Chalit chart can disagree on house lordship for planets near a sign boundary. Serious kundli apps render both: the rasi chart for sign-based logic and the Chalit chart to confirm true bhava placement. KP astrology uses a related cusp model (Placidus cusps subdivided by sub-lords), covered in the KP sub-lord theory guide.
Choosing the right system for your reading
| System | Cusp rule | Best paired with | House width |
|---|---|---|---|
| Whole-sign | Sign = house | Vedic, dasha, yogas, vargas | Always 30° |
| Placidus | Time-divided arcs | Western tropical, KP cusps | Unequal, latitude-dependent |
| Sripati / Bhava Chalit | Asc as house midpoint | North-Indian kundli, bhava verification | Unequal, derived from Asc + MC |
| Equal house | 30° from Ascendant degree | Simplified Western charts | Always 30° |
A useful rule of thumb: match the house system to the zodiac and tradition you are already committed to. For a sidereal Vedic chart, whole-sign is the consistent default and Sripati is the verification layer; for a tropical Western chart, Placidus is the expected default. Mixing a tropical zodiac with whole-sign houses, or a sidereal zodiac with Placidus, is defensible but should be a conscious decision — see the sidereal vs tropical guide for how the zodiac choice interacts with house cusps.
Requesting house systems via the API
House data is available on the V2 computation endpoints under /v2/astrology/*. These take flat birth fields and let you specify the system. The base URL is https://api.vedika.io and every request authenticates with an x-api-key header carrying a vk_live_* key. You can try the shapes below against the free sandbox with no key first.
cURL: fetch house cusps
curl -X POST https://api.vedika.io/v2/astrology/houses \
-H "x-api-key: vk_live_your_key_here" \
-H "Content-Type: application/json" \
-d '{
"datetime": "1991-08-10T14:30:00",
"latitude": 18.5204,
"longitude": 73.8567,
"timezone": "+05:30",
"system": "vedic",
"houseSystem": "whole_sign"
}'Swap "houseSystem" for "placidus" or "sripati" to get cusp-based output for the same birth moment. The response returns the twelve cusp longitudes, the sign and degree of each cusp, and the house occupancy of every planet under the chosen system, so you can render a chart or drive house-based interpretation directly.
JavaScript: compare two systems for the same birth
const BASE = "https://api.vedika.io";
const headers = {
"x-api-key": process.env.VEDIKA_API_KEY,
"Content-Type": "application/json",
};
const birth = {
datetime: "1991-08-10T14:30:00",
latitude: 18.5204,
longitude: 73.8567,
timezone: "+05:30",
};
async function houses(houseSystem, system = "vedic") {
const res = await fetch(`${BASE}/v2/astrology/houses`, {
method: "POST",
headers,
body: JSON.stringify({ ...birth, system, houseSystem }),
});
return res.json();
}
const [wholeSign, sripati] = await Promise.all([
houses("whole_sign"),
houses("sripati"),
]);
// Flag planets whose bhava differs from their rasi-based house
for (const planet of wholeSign.planets) {
const chalit = sripati.planets.find((p) => p.name === planet.name);
if (chalit && chalit.house !== planet.house) {
console.log(`${planet.name}: rasi house ${planet.house} -> bhava ${chalit.house}`);
}
}This pattern — compute whole-sign and Sripati side by side, then surface the planets that move — is exactly what a careful kundli app does before locking a reading. It catches the boundary cases that single-system charts hide.
Houses inside an AI reading
The main natural-language endpoint, POST /api/v1/astrology/query, accepts a question plus a nested birthDetails object and returns an interpreted answer grounded in computed houses. You pass the same birth fields and an optional speed: "fast" flag.
import os, requests
resp = requests.post(
"https://api.vedika.io/api/v1/astrology/query",
headers={"x-api-key": os.environ["VEDIKA_API_KEY"]},
json={
"question": "Which house systems shift my career significators?",
"birthDetails": {
"datetime": "1991-08-10T14:30:00",
"latitude": 18.5204,
"longitude": 73.8567,
"timezone": "+05:30",
},
},
)
print(resp.json()["answer"])Because every house placement in the answer is code-computed before the language layer ever sees it, the interpretation stays anchored to real cusps rather than to a guessed chart. For streaming output, the same payload works against /api/v1/astrology/query/stream over Server-Sent Events.
Edge cases worth handling
High latitudes
Time-divided systems like Placidus break down near the poles because some zodiac degrees never rise or set. Above roughly 66° latitude, prefer whole-sign or equal houses, and decide that fallback explicitly rather than letting cusps return undefined.
Unknown or approximate birth time
House cusps depend on birth time to the minute. If users supply only a date, whole-sign houses anchored to a noon chart degrade more gracefully than degree-based cusps, because the house grid only shifts when the Ascendant crosses a sign boundary.
Timezone and longitude precision
An incorrect timezone offset moves the Ascendant and every cusp with it. Always send an explicit timezone offset and exact coordinates. Cusp errors in production almost always trace back to a wrong offset or a rounded latitude, not the math.
Why precise cusps depend on a precise ephemeris
House cusps are only as trustworthy as the Ascendant and Midheaven they are built on, and those two points come from the ephemeris. Vedika computes positions with the XALEN Ephemeris, an open-source engine (Apache-2.0, available on crates.io, PyPI, and as a WASM package) with roughly 2,200 tests. It has been validated against JPL DE440 and swetest, with no chart deviating beyond 0.1° across a reproducible JPL DE440 benchmark run. That is astronomical precision — the position of the planets and angles — and it is what lets every house system above resolve to dependable cusps. More detail is in the open-source ephemeris explainer.
Key facts
- Vedika exposes whole-sign, Placidus, Sripati (Bhava Chalit), and equal houses as a request parameter on
/v2/astrology/*. - Whole-sign houses pair with Vedic dasha, yoga, and divisional-chart logic per Brihat Parashara Hora Shastra and Phaladeepika.
- Placidus is the modern Western default and is undefined inside the polar circles; fall back to whole-sign above ~66° latitude.
- Sripati / Bhava Chalit treats the Ascendant degree as the 1st-house midpoint, so a planet's bhava can differ from its rasi.
- House cusps depend on an accurate Ascendant and Midheaven, which depend on a precise ephemeris and a correct timezone offset.
- Three zodiac systems (Vedic, Western, KP) and 700+ operations across 25 domains are served from one API at
https://api.vedika.io.
Try the house endpoints free in the sandbox with no API key, browse request and response shapes in the documentation, or review plans on the pricing page when you are ready to move to a live key.
FAQ
Which house system should I use for a Vedic chart?
Whole-sign houses are the standard default for Jyotish work, and Sripati (Bhava Chalit) is the common verification layer for planets near a sign boundary. Many kundli apps render both and flag any planet whose bhava differs from its rasi-based house.
Can I get Placidus and whole-sign houses from the same birth data?
Yes. The underlying planetary positions are computed once from the ephemeris; the house system is a separate request parameter, so you can request whole-sign, Placidus, or Sripati cusps for the identical birth moment and compare them.
What happens to Placidus houses at very high latitudes?
Placidus is mathematically undefined inside the polar circles because some zodiac degrees never rise. Above roughly 66° latitude, switch to whole-sign or equal houses, and decide that fallback explicitly in your integration.
Does the house system affect an AI astrology reading?
It can. House placement drives most interpretation — career from the 10th, marriage from the 7th — so a planet that shifts houses between systems changes the reading. House cusps are code-computed before the language layer interprets them, so the answer stays anchored to real positions.