Korea Tide Calculator
Last updated: 2026-06-25
The tide is set by the lunar date. Pick a date and it converts to lunar to show the tide number, tide name, spring/neap status and the days to the next spring tide all at once.
Around the full moon (15th) and new moon (30th) is the spring tide (sari); around the lunar 8th and 23rd is the neap tide (jogeum). Based on the West Sea 7-tide system.
Pick a date
Tide
-
| Item | Value |
|---|---|
| Solar date | |
| Lunar date | |
| Tide (number) | |
| Tide name | |
| Tide phase | |
| Spring/neap | |
| Days to next spring tide | |
| Fishing outlook |
Tide names are reference values on the West Sea 7-tide system and may vary by 1-2 tides by region. For exact tide levels and high/low water times, check the Korea Hydrographic and Oceanographic Agency (KHOA) tide forecast.
How to use
- Pick a date — Use the date picker to choose the solar date you want the tide for. The default is today.
- Calculate — Press Calculate tide to show the lunar date, tide name and spring/neap status.
- Read the result — The tide number/name, lunar date, spring/neap and the days to the next spring tide appear in a table.
How the tide is calculated and the 7-tide system
This calculator converts solar to lunar using a lookup built from Korea Astronomy and Space Science Institute (KASI) lunar data. Because it uses official lunar data rather than computing astronomy directly, key dates such as Chuseok, Lunar New Year and the first full moon match exactly. It maps the converted lunar day (1-30) onto the West Sea 7-tide system.
| Lunar day | Tide | Phase | Current |
|---|---|---|---|
| 1st, 16th | 7-mul | Mid tide | Moderate |
| 4th, 19th | 10-mul | Spring | Strong |
| 8th, 23rd | Neap | Neap | Weak |
| 10th, 25th | 2-mul | Mid tide | Moderate |
| 13th, 28th | 5-mul | Mid tide | Moderate |
| 15th, 30th | Spring | Spring (full) | Very strong |
At the lunar full moon (15th) and new moon (30th), the moon, sun and Earth align for the largest range — the spring tide (sari); at the half moon (lunar 8th and 23rd) the range is smallest — the neap tide (jogeum). Spring and neap each occur twice a month, so the tide repeats on roughly a 15-day cycle. See a full month's flow in the tide calendar, and high/low water times in high/low water times.
Frequently asked questions (FAQ)
How is today's tide determined?
The tide is set by the lunar date. This calculator converts the solar date to lunar using Korea Astronomy and Space Science Institute (KASI) data, then assigns the tide with the West Sea 7-tide system (lunar 1st/16th = 7-mul, 8th/23rd = neap, 15th/30th = spring).
What are spring tide and neap tide?
Spring tide (sari) is the largest tidal range, around the full moon (15th) and new moon (30th); neap tide (jogeum) is the smallest range, around the lunar 8th and 23rd. The current is strong at spring tide and weak at neap tide.
How is the D-day to the next spring tide calculated?
It calculates the number of days from the chosen date to the next spring tide (full or new moon) using lunar data and shows it as a D-day. If the chosen day is itself a spring tide, it shows 'Today is a spring tide'.
Does the tide differ by region?
Yes. Tide counting can vary by 1-2 tides between regions such as the West Sea and South Sea and between fishing villages. This calculator uses the West Sea 7-tide system, so use it alongside local notation.
What date range is supported?
The built-in KASI lunar data supports 2024 to 2035. Dates outside this range show 'Out of range'; for exact lunar dates use the KASI lunar-solar conversion service.
Related tools & guides
Tide calendar (tide table)
See the tide, lunar date and spring/neap for every day of a month in one table.
High/low water times
Estimate approximate high/low water times by region.
Fishing info hub
See today's tide summary and seasonal fish info.
Feels-like temperature calculator
Check the feels-like temperature and suitability before you go.
Last updated: 2026-06-25