Couple Compatibility Test by Birth Date: How It Works

The birth date compatibility test compares the three biorhythm cycles of two people (physical, emotional, and intellectual) over a 30-day period and returns a score from 0 to 100. It has nothing to do with astrology. No zodiac signs and no planets: the cycles that begin on each person's date of birth are calculated, and the test looks at how they overlap

What exactly does the test compare?

Each person has three curves that rise and fall regularly from birth:

Physical cycle — 23 days
Energy, stamina, willingness to take action.

Emotional cycle — 28 days
Mood, sensitivity, patience.

Intellectual cycle — 33 days
Clarity, concentration, decision-making.

For a couple, the curves become six. The test compares them day by day and measures how often you are in the same phase. When both of you are in the same phase, harmony tends to come more naturally; when one is rising and the other is falling, more patience and communication may be needed.

The score is not a verdict

90 does not mean a perfect couple, and 40 does not mean “break up.” The number alone says very little: what really matters is understanding which axis comes naturally into sync and where your rhythms diverge.

Consider two people with low physical compatibility but high intellectual compatibility: they might experience more difficulty managing their energy levels (one wants to go out while the other wants to stay on the couch) than when making important decisions.

There is also something people often do not expect: comparing two birth dates does not change over time. The cycles are periodic, and birth dates remain the same. What changes is the position of the cycles from day to day, and therefore the snapshot of the period being considered.

It's not just for couples

TThe test weights the comparison according to the type of relationship: partners, friends, family members, colleagues, or acquaintances. With a colleague, intellectual compatibility matters most; with a partner, all three axes are taken into account. The calculation is the same—the interpretation criteria change.

How to take the test (in practice)

1. Open the compatibility test on BYOURIT.

2. Enter the two birth dates and select the type of relationship.

3. Within seconds, you get a score from 0 to 100 and a concise interpretation showing where compatibility is high and where more patience may be needed.

The initial result is free and does not require an account. The Premium version adds an in-depth analysis of each axis and the ability to save multiple people.

FAQ

Is the time of birth required?
No: classic biorhythm cycles are calculated using only the date of birth.

Is it scientifically reliable?
The biorhythm model has a long history and originated between the late 19th and early 20th centuries (Fliess 1897, Swoboda 1904, Teltscher in the 1920s). However, classical biorhythm theories have not received robust scientific validation as a method for predicting individual states or behaviors. We therefore present it transparently: as a tool for reflecting on a relationship, not as a scientifically predictive method.

Is it spelled biorhythm or bio rhythm?
The correct form is biorhythm (plural: biorhythms).

Can I do it with a friend instead of my partner?
Yes: simply choose “friendship” as the relationship type, and the calculation will adapt accordingly.