What does 'ripe' mean here?

The day the study called optimally ripened. The mark is pH and acidity, and it differs by study: the napa kimchi-fridge study uses pH 4.4 · acidity 0.6%, the gat kimchi study pH 4.6~4.8, the nabak kimchi study pH 4.2~4.5 · acidity 0.20~0.25%. The chip under the answer prints the mark used for your kimchi.

How long in a kimchi fridge straight away?

In Lee et al. 2012, kimchi put straight into a kimchi fridge reached pH 4.4 · acidity 0.6% after 12 weeks at −1 °C and 22 weeks at −2.5 °C.

How long to ferment kimchi at room temperature first?

The same study measured two recipes: '1 day at 15 °C, then kimchi fridge' took 8 weeks, '5 days at 10 °C, then kimchi fridge' took 2 weeks. No other room-temperature span was measured, so the tool offers only these two.

How long to ferment kimchi in the fridge?

Napa kimchi at 4 °C (Lee et al. 1992) reached pH 4.2 · acidity 0.63% after 30 days. The Korea Meteorological Administration's line is “담근 김장은 2∼7℃에서 2∼3주정도 지나야 제 맛을 내기 시작함”. Both are shown because they differ.

Why is there no sour date?

Only two studies observed it: napa kimchi at 10 °C (Song et al. 1995, taste scores fell from 21 days) and at 15–16 °C (Chang & Kim 2000, acidity above 0.75% after 8 days). Elsewhere the strip ends where the study stopped watching.

Why no chonggak or green-onion kimchi?

No study with a ripe day was found. The chonggak study gives only the end of the edible period, the green-onion and garlic-chive study has no pH or acidity numbers, and none was found for stuffed cucumber or seokbakji.

How Long to Ferment Kimchi? Ripe-Date Calculator (Fridge, Room Temp, Kimchi Fridge)

How it works

Criteria, method, where studies disagree

Each study defines 'ripe' its own way

Only the studies the calculator uses. Spans count from the day it was made.
Kimchi	Storage	Study temp	Criterion	Ripe after	Study
Napa cabbage kimchi	5 days at 10 °C, then kimchi fridge	10 °C 5 days → −2.5 °C	pH 4.4 · acidity 0.6%	2 weeks	Lee et al. 2012
Napa cabbage kimchi	1 day at 15 °C, then kimchi fridge	15 °C 1 day → −2.5 °C	pH 4.4 · acidity 0.6%	8 weeks	Lee et al. 2012
Napa cabbage kimchi	Straight into a kimchi fridge (−1 °C)	−1 °C	pH 4.4 · acidity 0.6%	12 weeks	Lee et al. 2012
Napa cabbage kimchi	Straight into a kimchi fridge (−2.5 °C)	−2.5 °C	pH 4.4 · acidity 0.6%	22 weeks	Lee et al. 2012
Napa cabbage kimchi	Regular fridge (4–5 °C)	4 °C	pH 4.2 · acidity 0.63%	30 days	Lee et al. 1992
Napa cabbage kimchi	Cool place the whole time (10 °C)	10 °C	pH 4.17~4.36 · acidity 0.45~0.52%	7 days	Song et al. 1995
Napa cabbage kimchi	Cool room the whole time (15–16 °C)	16 °C (sour: 15 °C)	pH 4.3	3 days	Noh et al. 1992 · Chang & Kim 2000
Kkakdugi (cubed radish)	Cool room the whole time (15–16 °C)	15 °C	acidity 0.6%	6 days	Kim et al. 2002
Kkakdugi (cubed radish)	Cool place the whole time (10 °C)	10 °C	acidity 0.6%	7 days	Kim et al. 2002
Kkakdugi (cubed radish)	Regular fridge (4–5 °C)	5 °C	acidity 0.6%	18 days	Kim et al. 2002
Yeolmu kimchi (young radish greens)	Regular fridge (4–5 °C)	5 °C	pH 4.3	2–3 weeks	Kong et al. 2005a
Gat kimchi (mustard leaf)	Regular fridge (4–5 °C)	4 °C	pH 4.6~4.8	78–96 days	Park et al. 1995
Gat kimchi (mustard leaf)	12–36 h at 20 °C, then regular fridge	20 °C 12–36 h → 4 °C	pH 4.6~4.8	68–88 days	Park et al. 1995
Gat kimchi (mustard leaf)	Warm room the whole time (20–25 °C)	20 °C	pH 4.6~4.8	6–9 days	Park et al. 1995
Baek kimchi (white kimchi)	Regular fridge (4–5 °C)	5 °C	pH 4.25~4.40 · acidity 0.34~0.53%	9–12 days	Moon & Ryu 1997
Baek kimchi (white kimchi)	Warm room the whole time (20–25 °C)	25 °C	pH 4.02 · acidity 0.54%	3 days	Moon & Ryu 1997
Dongchimi (radish water kimchi)	Regular fridge (4–5 °C)	5 °C	pH 3.9~4.2 · acidity 0.1~0.4%	9–12 days	Ko et al. 1995
Nabak kimchi (sliced radish water kimchi)	Regular fridge (4–5 °C)	5 °C	pH 4.2~4.5 · acidity 0.20~0.25%	8 days	Kong et al. 2005b
Nabak kimchi (sliced radish water kimchi)	Cool place the whole time (10 °C)	10 °C	pH 4.2~4.5 · acidity 0.20~0.25%	3 days	Kong et al. 2005b
Nabak kimchi (sliced radish water kimchi)	Warm room the whole time (20–25 °C)	20 °C	pH 4.2~4.5 · acidity 0.20~0.25%	1 day	Kong et al. 2005b

Method

Count from the day it was made. 'N days' in a study means N days later, 'N weeks' N weeks later, 'N months' the same date N months later (or the last day of that month).

If the kimchi you picked has no study for that storage, the napa-cabbage study is used as an approximation and the answer, card and calendar say so. Dongchimi and nabak kimchi are water kimchi with a different acidity scale, so they are never approximated.

When a study gives one day, the tool adds a margin (±2 days for day-reported results, ±3 for week-reported ones). When a study gives a range, the range is shown as is.

The strip runs fresh → ripe → well aged → sour. If the study never observed a sour day, it stops at the last day the study observed, or shows 'no study after this'. The widths are for reading; the dates are the data.

Where studies disagree

Napa kimchi in a regular fridge uses Lee et al. 1992 (30 days). The Korea Meteorological Administration wrote (in Korean): “담근 김장은 2∼7℃에서 2∼3주정도 지나야 제 맛을 내기 시작함”.

A cut-cabbage study (Choe et al. 1995) reports when pH 4.0 (more sour than ripe) was reached: “decreased to 4.0 … at 8°C during 6 days, at 4°C during 18days, 0°C during 42 days”.

Dongchimi in a kimchi fridge (Noh et al. 2008): “최적 pH 3.9±0.1·산도 0.25±0.05% · 10℃에서 산도 0.2%까지 → −2.5±0.5℃ 저장 제안 · 기존 자동숙성 모드는 30일 안에 적숙 못 함”. So dongchimi is not approximated from napa cabbage in a kimchi fridge. The dongchimi 10 °C result ripens later than 5 °C, an implausible order, so it is not used.

Kimchi-fridge mode names differ by brand, so the study temperature is printed, never a mode name.

Ripening calendar as a table

Stage	From	To
Fresh	Mon, Nov 9	Mon, Nov 9
Ripe	Tue, Nov 10	Sat, Nov 14
Well aged	Sun, Nov 15	Mon, Nov 16
Sour (for stew)	Tue, Nov 17	Tue, Dec 1

Questions

What does 'ripe' mean here?: The day the study called optimally ripened. The mark is pH and acidity, and it differs by study: the napa kimchi-fridge study uses pH 4.4 · acidity 0.6%, the gat kimchi study pH 4.6~4.8, the nabak kimchi study pH 4.2~4.5 · acidity 0.20~0.25%. The chip under the answer prints the mark used for your kimchi.
How long in a kimchi fridge straight away?: In Lee et al. 2012, kimchi put straight into a kimchi fridge reached pH 4.4 · acidity 0.6% after 12 weeks at −1 °C and 22 weeks at −2.5 °C.
How long to ferment kimchi at room temperature first?: The same study measured two recipes: '1 day at 15 °C, then kimchi fridge' took 8 weeks, '5 days at 10 °C, then kimchi fridge' took 2 weeks. No other room-temperature span was measured, so the tool offers only these two.
How long to ferment kimchi in the fridge?: Napa kimchi at 4 °C (Lee et al. 1992) reached pH 4.2 · acidity 0.63% after 30 days. The Korea Meteorological Administration's line is “담근 김장은 2∼7℃에서 2∼3주정도 지나야 제 맛을 내기 시작함”. Both are shown because they differ.
Why ±2 or ±3 days?: Papers only give the day they measured. The ± is a margin this tool adds: ±2 days for day-reported results, ±3 for week-reported ones. When a study gives a range (dongchimi 9–12 days), the range is shown without ±.
Why is there no sour date?: Only two studies observed it: napa kimchi at 10 °C (Song et al. 1995, taste scores fell from 21 days) and at 15–16 °C (Chang & Kim 2000, acidity above 0.75% after 8 days). Elsewhere the strip ends where the study stopped watching.
Why no chonggak or green-onion kimchi?: No study with a ripe day was found. The chonggak study gives only the end of the edible period, the green-onion and garlic-chive study has no pH or acidity numbers, and none was found for stuffed cucumber or seokbakji.

Sources

Study	What we use	Checked
Lee E-H, Lee M-J, Song YO (2012) 김치냉장고의 숙성 후 저장 및 저온 저장 모드에서 6개월간 저장한 김장 김치의 발효특성 비교. J Korean Soc Food Sci Nutr 41(11):1619–1625. doi:10.3746/jkfn.2012.41.11.1619	time to reach "pH 4.4 and acidity 0.6%" was "2, 8, 12, and 22 weeks" for F1, F2, S1, S2 (F1 10℃ 5d→−2.5℃; F2 15℃ 1d→−2.5℃; S1 −1℃; S2 −2.5℃)	2026-11-09
Lee M-H, Jun H-K, No H-K (1992) 저온발효 배추김치의 품질평가를 위한 김치액의 색상 측정. J Korean Soc Food Sci Nutr 21(6):677–680	has reached pH 4.2 and titratable acidity of 0.63% … under the optimum ripening period, after 30 days of fermentation	2026-11-09
노홍균, 이명희, 이명숙, 김순동 (1992) 김치액의 색상에 의한 배추 김치의 품질 평가. J Korean Soc Food Sci Nutr 21(2):163–170	has reached pH 4.3, the pH value under an optimum ripening period, after 3-days fermentation at 16°C · At 4°C the kimchi was unripened after 6-days fermentation	2026-11-09
장문정, 김명환 (2000) 발효온도 및 소금농도에 따른 배추김치의 발효 특성. Applied Biological Chemistry 43(1):7–11	The maximum edible acidity, 0.75%, was reached within 8 days at 15°C	2026-11-09
Song J-E, Kim M-S, Han J-S (1995) 배추 절임 방법이 김치의 맛과 숙성에 미치는 영향. Korean J Food Cookery Sci 11(3):226–232	저장 7일째가 가장 맛있게 평가되었고 · 26일 "pH, 산도, 염도가 각각 3.69-4.01, 0.68-0.74 …"	2026-11-09
김영애, 이숙희, 정근옥, 박건영, 문숙희 (2002) 저장온도와 포장방법에 따른 깍두기의 발효특성. J Korean Soc Food Sci Nutr 31(6):971–976	The required days to reach the acidity of 0.6% (optimally ripened state) were 6 days at 15°C, 7 days at 10°C, 18 days at 5°C and 30 days at 0°C.	2026-11-09
고은정, 허성선, 박미, 최용희 (1995) 이온음료 제조를 위한 동치미의 최적 담금 조건에 관한 연구. J Korean Soc Food Sci Nutr 24(1):141–146	24~29 days at 0°C, 9~12dyas at 5°C and 16~22days at 10°C (sic)	2026-11-09
노정숙 외 (2008) 동치미 최적발효 및 저장을 위한 김치냉장고의 자동숙성 시스템 개발. Korean J Food Sci Technol 40(6):661–668	최적 pH 3.9±0.1·산도 0.25±0.05% · 10℃에서 산도 0.2%까지 → −2.5±0.5℃ 저장 제안 · 기존 자동숙성 모드는 30일 안에 적숙 못 함	2026-11-09
문수경, 류홍수 (1997) 백김치 숙성중 식이섬유 및 펙틴질의 함량변화. J Korean Soc Food Sci Nutr 26(6):1006–1012	Ripened Baik-kimchi products fermented at 5°C could be prepared on 9~12 days of fermentation	2026-11-09
박삼수, 장명숙, 이규환 (1995) 발효숙성온도를 달리한 갓 김치의 저장중 이화학적 특성 변화. J Korean Soc Food Sci Nutr 24(5):752–757	적숙기라 할 수 있는 pH 4.6~4.8이 되는 시기는 A군이 발효 78~96일, B군은 6~9일, 그리고 C, D군은 모두 68~88일	2026-11-09
공창숙 외 (2005) 열무김치 및 열무물김치의 발효특성과 in vitro 항암효과. J Korean Soc Food Sci Nutr 34(3):311–316	발효 2-3주일 째에 김치 적숙기의 pH에 도달하였으며	2026-11-09
공창숙, 서정옥, 박석신, 이숙희, 박건영 (2005) 나박김치의 제조 표준화 및 발효온도별 젖산균의 생육과 CO₂ 생성. J Korean Soc Food Sci Nutr 34(5):707–714. doi:10.3746/jkfn.2005.34.5.707	Fermentations at 5°C for 8 days, at 10°C for 3 days, and at 20°C for 1 day led to the acidity levels of 0.21%, 0.20%, and 0.31%	2026-11-09
기상청 보도자료 「2001년도 김장시기 예상」 2001-11-09	담근 김장은 2∼7℃에서 2∼3주정도 지나야 제 맛을 내기 시작함	2026-11-09
Kim B-Y, Ahn T-Y, Kim M-H (1999) n-Capric acid … 첨가와 저장온도에 따른 김치의 발효특성. Applied Biological Chemistry 42(2):156–161	reached within 3 days at 20°C, 15 days at 12°C, and the acidity of 42 days at 4°C was 0.62%	2026-11-09
최기찬, 김미연, 정신교 (1995) 저장온도 및 포장재에 따른 절단배추 김치의 품질변화 및 Shelf-life. Food Sci Preserv 2(2):277–284	decreased to 4.0 … at 8°C during 6 days, at 4°C during 18days, 0°C during 42 days	2026-11-09
노정숙 외 (2007) 배추김치의 최적발효 및 저장을 위한 김치냉장고의 자동숙성 시스템 개발. Korean J Food Sci Technol 39(4):432–437	초기 발효 10~15℃ 적절, 산도 0.4%에서 저장 전환 제안, 저장 −2±0.5℃	2026-11-09
Moon SH, Kim EJ, Kim EJ, Chang HC (2018) Development of fermentation·storage mode for kimchi refrigerator… Korean J Food Sci Technol 50(1):44–54. doi:10.9721/KJFST.2018.50.1.44	fermentation time of 4-7 days in winter and 3-5 days in spring and fall	2026-11-09

Numbers checked 2026-11-09

Illustrations: AI-generated (Gemini), edited by plusbeauxjours

Lab averages. Salt, seasoning, jar size and fridge change them. Check by taste and smell.

When will my kimchi be ready?

Ripening calendar

Your jar