Two Saju calculators disagree? Compare their actual pillars and raw element counts, follow targeted checks, and reproduce three public experiments. Free local tools.
Calculate your chart, explore an unknown hour, or compare conflicting calculator results in the comparison lab below. No account, personal birth-record upload or AI wait.
COMPARISON LAB · SAME PERSON, DIFFERENT CALCULATIONS
Why do two Saju calculators disagree?
Place results A and B side by side to locate changed characters and counting assumptions. No additional birthday or AI request is needed. This compares calculations of the same birth record, not compatibility between two people.
Copy in Year → Month → Day → Hour order. Some apps display the reverse order. Enter six or eight Chinese characters; omit only the last pair if the Hour is unknown.
Inputs and comparisons stay in this screen’s memory. They are not saved or sent to a server, AI service, or analytics event. Clear inputs empties the current inputs and result. The optional exported record contains both charts; inspect it before sharing.
Validation checks individual pair notation only, not whether all four pairs belong to a real date or were copied correctly.
Enable JavaScript to compare your own results. The public experiments below require no input.
Three reproducible comparison experiments
These are not customer case studies or independent comparisons of competing providers. Each experiment changes an input or convention within one public library. The differences explain behavior; they do not certify a school or output as correct.
01 · Eight characters versus six
2000-01-01 12:00, sect 2. A includes the Hour; B omits only the Hour from the same calculation.
A: 己卯 丙子 戊午 戊午 B: 己卯 丙子 戊午
Day Master 戊 and the Year, Month and Day pairs match. Removing Hour 戊午 removes one Earth and one Fire unit, reducing the denominator from eight to six. Water stays at one unit, yet its share rises from 12.5% to about 16.7%. The denominator changed, not a measured personal strength.
Check that the Hour is marked insufficient data rather than different, and that both Water counts remain one.
02 · The Day convention at 23:00
2000-01-01 23:00. Identical input; A uses sect 2 and B uses sect 1. No location or timezone correction.
A: 己卯 丙子 戊午 甲子 B: 己卯 丙子 己未 甲子
In library 1.7.7, A gives Day 戊午 and B gives 己未, while both retain Hour 甲子. The Day Masters 戊 and 己 are different characters but both map to Earth. Matching Day Master elements is not the same as matching Day Masters.
Open the example and verify that only Day is marked different. Do not assume another provider’s discrepancy has this cause without checking its settings.
03 · One date, times on opposite sides of a solar term
2026-02-04, sect 2. A uses 00:00; B uses 23:00. This sensitivity experiment fixes the date but changes the input hour.
A: 乙巳 己丑 己酉 甲子 B: 丙午 庚寅 己酉 丙子
In this engine, Year and Month move from 乙巳 / 己丑 to 丙午 / 庚寅, while Day remains 己酉. Hour also changes. Sharing a date does not guarantee matching Year and Month pillars. These two samples do not establish the exact transition minute or its Korean-standard-time equivalent.
Separate the three changed positions from the unchanged Day. To verify a real record, obtain a solar-term reference with the relevant location and time standard.
Reproduction basis: lunar-javascript 1.7.7, Solar.fromYmdHms → getLunar → getEightChar, with setSect. Automated tests checked these three outputs on 2026-10-16. This is same-engine regression checking, not independent astronomical certification.
For an initial chart and character ledger, use the Five Elements calculator. For an unknown hour, use the 24-hour explorer. If you already have two conflicting results, use the comparison lab on this page: it identifies mismatched positions, recalculates raw counts and suggests checks based on the actual differences.
Know what the numbers mean
These are simplified calendar and symbol-counting tools, not a full professional chart. Neither tool corrects for birthplace, historical timezone, daylight saving, or true solar time. A percentage counts visible symbols; it does not measure personality, health, or good fortune.
Common questions
Are these tools free?
Yes. The calculations run locally without a paid reading or an account.
Which tool should I use without a birth time?
Start with the birth-time explorer to see sensitivity across sampled hours. It cannot discover your real birth time; use original records or independent calendar sources for that.