Marine Corps Cohort Calculator
Look up Korean Marine Corps cohort dates from confirmed historical entries and the last-Monday rule from cohort 1157 onward. Missing historical entries and dates that do not match the known rule are shown as unknown instead of being adjusted.
Estimation Results
Cohort
1300th
Enlistment Date
Mon, November 27, 2023
For cohorts 1-1156, only confirmed table entries are shown. From cohort 1157 onward, the calculator uses the last Monday of each month. Confirm official records with the Military Manpower Administration or Marine Corps notices.
Marine Corps Cohort Data and Estimate Limits
Reference date and last reviewed: July 11, 2026
Calculation Basis
Uses confirmed historical cohort and enlistment-date table entries first, then applies a last-Monday-of-the-month rule as a reference for cohorts after 1157 when no confirmed table date is available.
Reference Limits
It cannot fully correct for historical recruiting cycles, holidays, training-center operations, schedule changes, or differences between source tables. The result is a lookup estimate, not an official cohort or enlistment date.
When to Confirm Officially
For service records, official submissions, or enlistment planning, compare the result with MMA recruiting plans, the enlistment order, and official Marine Corps guidance.
Usage Tips
Check Korean Marine Corps cohorts and enlistment dates
Look up Korean Marine Corps cohort and enlistment dates from confirmed historical entries and the last-Monday rule from cohort 1157 onward. Missing historical entries are shown as unknown.
What is Marine Corps Cohort Calculator?
The Marine Corps Cohort Calculator looks up Korean Marine Corps cohort numbers and enlistment dates in both directions. For cohorts 1 through 1156, it only shows confirmed historical table entries and marks missing historical dates as unknown instead of interpolating them. Cohorts 1157 onward use the last Monday of each month, while confirmed recent anchors such as cohort 1331 are used first. Historical and recent results can differ from official cohort tables, so treat them as reference information only.
How to Use
- 1Choose a calculation mode: cohort to enlistment date, or enlistment date to cohort.
- 2In Cohort mode, enter a Marine Corps cohort number such as 1, 1157, 1300, or 1331. Listed historical dates are shown from the table, and cohorts 1157 onward are shown with the last-Monday rule.
- 3In Enlistment Date mode, select a date on or after April 5, 1949.
- 4Review the cohort and enlistment date cards.
- 5Check the result notice to see whether the date is table-based or based on the last-Monday rule, and compare with official sources when accuracy matters.
Separating confirmed cohort dates from the monthly estimate
Last reviewed: July 11, 2026Cohort lookup model
Post-1157 estimated date = base month + cohort offset → last Monday of that month
Cohorts 1-1156 return dates only from the stored confirmed table. Later cohorts use the monthly interval model, while separately confirmed recent dates such as cohort 1331 override that rule.
Looking up cohort 1300 and the 1331 anchor
- • Cohort 1300
- • Cohort 1157 base date 2011-12-26
- • Confirmed recent value: cohort 1331 = 2026-06-29
- 1. 1300 - 1157 = 143 months
- 2. 143 months after December 2011 is November 2023
- 3. The last Monday of November 2023 is 2023-11-27
Cohort 1300 is shown as November 27, 2023 under the monthly model, while cohort 1331 uses the confirmed June 29, 2026 date.
How to read the result
- Table-based and monthly-model results have different evidence levels, so check the model notice with the date.
- Leaving an unknown historical date blank avoids presenting an interpolation as an official personal record.
Conditions that change the result
- Cohorts 1-1156 can be looked up only when a table entry exists; missing historical dates are not interpolated.
- Recruiting schedules, holidays, training-center operations, and cohort practices can differ from the monthly rule.
Common input mistakes
- Do not read cohort 1300 as 1,300 months; the tool calculates a month offset from the base cohort.
- A date that is not a Monday is not automatically invalid; check whether it is a confirmed historical table date first.
Reference Knowledge
- ●From the 1157th cohort onward, the calculator uses the last Monday of each month, while confirmed recent cohort dates are used first.
- ●For cohorts 1-1156, only known historical enlistment dates are shown; missing dates are treated as unknown.
- ●Actual enlistment dates and cohort numbers can vary because of holidays, training-center schedules, recruiting changes, and historical cohort practices.
- ●For official use, confirm the final cohort and enlistment date with the Military Manpower Administration, Marine Corps notices, enlistment order, or a verified historical cohort table.
FAQ
Q.Can I calculate from the 1st Marine Corps cohort?
Yes. Cohort 1 is accepted. If a confirmed enlistment date is listed, the calculator uses that date directly. Missing historical dates are not filled with interpolation.
Q.Can historical estimates differ from official cohort tables?
Yes. Recruiting cycles and enlistment schedules changed over time, so historical estimates may differ from official records. Use official notices or verified tables for confirmation.
Q.Does date-to-cohort mode use the same model?
Yes. If the date matches a confirmed historical cohort date, that cohort is used first. For cohorts 1157 onward, the date must match the last Monday of the month.
Q.Why are some historical cohorts shown as unknown?
Filling missing dates with an average or adjustment can make an unconfirmed date look official. This tool only uses listed dates and the last-Monday rule from cohort 1157 onward.
Q.What should I do if a cohort date looks different from my records?
Historical cohort dates can vary by source, recruiting schedule, and training-unit operation. For personal records or official use, confirm the final date with enlistment notices, Marine Corps guidance, or a verified historical cohort table.
