Love Calculator by Date of Birth

Birthday compatibility on this site blends two Tradition readings, the sun-sign match and the life-path match, into one score from two dates of birth, with both components shown and linked to their pair pages.

What is birthday compatibility?

Birthday compatibility is a reading of how well two people fit, made from their two dates of birth alone. The love calculator by date of birth reads two birthdays through the sun sign and the life path number and blends both into one score, with each component shown.

Other sites read a birthday through astrology only or through numerology only. This page shows both components, so it answers both senses. It's one Tradition route to love compatibility. It follows two systems that many people find meaningful, and it says nothing about evidence. The sun-sign half is the next thing to know, and zodiac sign compatibility covers it in full.

How do you check compatibility by date of birth?

To check compatibility by date of birth, enter both dates in the tool above and press the button. The check takes four steps:

1. Enter the first date of birth.
2. Enter the second date of birth.
3. Press "Calculate the blend".
4. Read the combined score and the two lines under it, one for your sun signs and one for your life paths.

The birthday compatibility calculator is free, asks for no birth time and runs in your browser. People also call it a birthday compatibility test or a love compatibility calculator by date of birth. The four steps are the same under every name.

How is birthday compatibility calculated?

Here is how it works: each date gives a sun sign and a life path number, each pair gets its own score, and the two scores are averaged. The steps below are the ones the tool runs.

1. Each birth date gives a sun sign from fixed date ranges. A date on a boundary day is flagged, because the changeover shifts by up to a day.
2. The two signs are rated the way the zodiac tool rates them, out of 8 points, and that is scaled to 100.
3. Each date gives a life path number: the month, the day and the year are each reduced, added, and reduced again. 11, 22 and 33 are kept.
4. The two life paths are looked up on the 9 by 9 numerology grid.
5. The combined reading is half the sign score and half the grid score. Both parts are always shown.

The sun sign comes from the dates most calendars use. A birthday on the first or last day of a sign counts as a boundary day. The result then shows both neighbouring signs, because the true changeover shifts by up to a day.

The two signs are rated on three things from Western astrology: their elements, their modalities and the aspect between them, which is how many signs apart they sit. The two life path numbers are looked up on a nine by nine grid. Master numbers 11, 22 and 33 are matched there through 2, 4 and 6. Each half becomes a score out of 100, and the combined score is half of one plus half of the other. The sign points and the half-and-half weighting are this site's own scoring of traditional readings. Both are marked PROPOSED on the methodology page.

The life path half uses the same method as the numerology calculator, which is covered under numerology compatibility. Two dates can't give a birth chart. A birth time and a birth place are needed for the full chart, and that's the job of birth chart compatibility (synastry).

What does the combined birthday compatibility rating mean?

The combined birthday compatibility rating is a compatibility score out of 100 that averages two Tradition readings of the same two birthdays, the sun sign reading and the life path reading. It is a summary of what two systems say, not a third system and not a measurement of the two of you. That's why the result never shows it alone.

Under the score, the result names the sign pair page and the life path pair page for your two dates, and links each one as it is published. The table reads the three lines of the result.

All three lines appear at every score, so you can always see which half moved the number.

A calculator reads two dates, and two dates are all this result claims to read.

Why does the result show a sun sign score and a life path score?

The result shows a sun sign score and a life path score because the blend is an average of two different traditions. Showing both lets you see which one moved the number. A pair can score high in one and low in the other, and the average alone would hide that.

Zodiac elements and compatibility

Western astrology sorts the twelve signs into four elements:

• Fire: Aries, Leo, Sagittarius
• Earth: Taurus, Virgo, Capricorn
• Air: Gemini, Libra, Aquarius
• Water: Cancer, Scorpio, Pisces

The tradition reads same-element pairs and trines (four signs apart) as the easiest, fire with air and earth with water as friendly, and squares and oppositions as tension. An aspect is the distance between two signs on the wheel, and the seven aspects are the conjunction, semisextile, sextile, square, trine, quincunx and opposition. Signs of the same modality (cardinal, fixed or mutable) are read as more of a contest.

Numerology by date of birth

Pythagorean numerology turns each date of birth into one number and then reads the pair:

• Reduce the date: the month, the day and the year each become one digit, the three are added, and the total is reduced again.
• Keep the life path number: the number you end with, 1 to 9, or a master number 11, 22 or 33, which the grid matches through 2, 4 and 6.
• Read the pair: one popular way to read life path pairs sorts the nine numbers into three groups, 1-5-7, 2-4-8 and 3-6-9, and treats numbers in the same group as natural matches.

Not every numerologist uses it: numerology.com, for example, lists matches number by number and rates 3 with 6 as a difficult pair. Our grid uses the three-group reading and says so. Because one half of the score is the zodiac, readers ask whether this is simply zodiac compatibility.

Is date of birth compatibility the same as zodiac compatibility?

No. Zodiac compatibility reads two sun signs and stops. Date of birth compatibility here reads the sun signs and the life path numbers from the same two dates and averages them. People search for this one tool as compatibility by birthdate, date of birth compatibility, astrology compatibility by date of birth, horoscope compatibility by birth date and zodiac compatibility by birthday. The sun-sign reading on its own, with the reasoning for your exact pair, is on the zodiac hub and its pair pages.

What does birthday compatibility leave out?

Birthday compatibility leaves out almost everything an astrologer would look at. A date gives the sun sign only. The Moon, Venus, Mars and the rising sign need a birth time and a birth place, and the numerology half uses one number out of several. Both halves are traditions, and controlled tests have found no evidence that birth dates predict how two people get on. The birth chart compatibility tool on this site is the fuller Tradition reading.

Two birthdays are one way to check your compatibility, and the hub lists every compatibility test we run, each with its label.