As an Amazon Associate, TidyJapan earns from qualifying purchases. Links marked ‘Check price’ are affiliate links.
Short answer: The SW-KA52 holds 18 oz versus 14 oz, is 3/4 inch taller, weighs 1 oz more, and has the best heat rating of the line: 153°F after 6 hours versus 147°F. It only comes in Matte Green and Beige. The SW-KA40 also comes in Ice Gray. For a kid-size portion, the 10 oz SW-KA30 is rated at 136°F.
How we compare: every spec in this article comes from official manufacturer specifications and manuals (starting with Zojirushi’s official product page), all listed under Sources below. We don’t run hands-on tests, and if a spec isn’t published, we say so. Last updated: October 2026.
I live in Japan. Same jar, three sizes. The real question is how much food you pack, so here are the numbers side by side.
I haven’t tested these side by side. Everything below comes from the manufacturers’ official product pages, linked at the end. If a spec isn’t published, I say so instead of guessing.
Quick Comparison Table
| Spec | SW-KA30 | SW-KA40 | SW-KA52 |
|---|---|---|---|
| Capacity | 10 oz / 0.30 L | 14 oz / 0.40 L | 18 oz / 0.52 L |
| Dimensions (W x D x H) | 3-7/8 x 3-7/8 x 4-3/8 in | 3-7/8 x 3-7/8 x 5 in | 3-7/8 x 3-7/8 x 5-3/4 in |
| Weight | 0 lb 11 oz | 0 lb 12 oz | 0 lb 13 oz |
| Heat after 6 hours* | 136°F | 147°F | 153°F |
| Cold after 6 hours* | 50°F | 48°F | 48°F |
| Colors | Ice Gray, Matte Green, Beige | Ice Gray, Matte Green, Beige | Matte Green, Beige |
*Zojirushi rates heat retention with 203°F (95°C) water in a 68°F (20°C) room, and cold retention with 40°F (4°C) water in the same room.
Key differences at a glance
- Capacity: The SW-KA52 holds 18 oz, 4 oz more than the SW-KA40’s 14 oz.
- Heat retention: The SW-KA52 is rated at 153°F after 6 hours, while the SW-KA40 is rated at 147°F.
- Colors: The SW-KA40 comes in Ice Gray, Matte Green, and Beige, while the SW-KA52 drops Ice Gray.
- What stays the same: Both share the 3-7/8-inch footprint, 2-7/8-inch opening, Therma Chamber lid, and leak-proof one-piece stopper.
The 3 Differences That Matter
1. Capacity and portion
18 oz is a generous adult serving of soup or stew. 14 oz suits a normal lunch portion, and 10 oz is a snack or a child’s meal.
2. Heat retention climbs with size
136°F, 147°F, then 153°F after 6 hours. If you pack early and eat late, size up.
3. Color
Ice Gray isn’t offered on the SW-KA52.
What’s the same
Every size shares the 3-7/8-inch footprint, 2-7/8-inch opening, Therma Chamber lid, and leak-proof one-piece stopper.
Who Should Buy Which?
Choose the SW-KA40 if you:
- Want a standard lunch portion
- Want Ice Gray
Choose the SW-KA52 if you:
- Want the most food and the best 6-hour rating
- Have room for a 5-3/4-inch jar
400 or 520 mL: How Zojirushi Japan Frames It
Zojirushi Japan sells both sizes, and frames the choice by what goes inside: the 400 mL SW-KA40 for soups with large chunks, and the 520 mL SW-KA52 for filling curry or stew. Japan specs rate the SW-KA40 at 64 °C and the SW-KA52 at 67 °C or higher after 6 hours, both with a 7 cm mouth. In Japan the SW-KA52 comes in matte green and beige, while the SW-KA40 also comes in ice gray. Japanese suggested prices are 6,600 yen and 7,150 yen. US colors may differ.
Japanese reviewers on Rakuten and Kakaku.com often say the SW-KA keeps soup warm until lunch, especially if the jar is preheated with hot water, and like its wide mouth and few parts; one recurring gripe is that the large lid is hard to open one-handed. (Third-party reviews, not our own testing.)
SW-KA40 vs SW-KA52: Frequently Asked Questions
Which SW-KA keeps food hottest?
The SW-KA52: 153°F after 6 hours.
Are they all the same width?
Yes, 3-7/8 inches.
Is the SW-KA52 available in gray?
No. Zojirushi lists only Matte Green and Beige.
How does the SW-KA30 compare to a kids’ Thermos?
See my SW-KA30 vs Thermos FUNtainer 10 oz comparison.
Check current listings
Prices and colors change often, so check the current listing before buying.
Related comparisons
- Zojirushi SW-KA40 vs SW-EAE50: Which Food Jar to Buy?
- Zojirushi SW-KA30 vs Thermos FUNtainer 10 oz: Kids’ Jars
- Zojirushi SW-EAE35 vs SW-EAE50: 12 oz or 17 oz Food Jar?
- Zojirushi SW-LA40 vs SW-KA40: What Changed in the New Jar?
Sources
- Zojirushi, Stainless Steel Food Jar SW-KA30/40/52 (official): https://www.zojirushi.com/app/product/swka
- Zojirushi Japan: SW-KA soup jar specs (zojirushi.co.jp): https://www.zojirushi.co.jp/syohin/bento/soup_jar/sw-ka/
- Rakuten user reviews: Zojirushi SW-KA40 (Japanese): https://review.rakuten.co.jp/item/1/405752_10000164/1.1/
- Kakaku.com: Zojirushi SW-KA40 reviews (Japanese): https://kakaku.com/item/K0001480100/
Specs checked October 2026. Prices and availability change, so check the current listing before buying.
Leave a Reply