Japanese Vacuum Mugs Compared on Maker Specs: Zojirushi SM-ZB and Tiger MKA-K

Specifications checked: October 3, 2026 | Buy from Japan | Japanese Best

Japanese makers publish heat- and cold-retention figures for their vacuum mugs using the same kind of test. That makes it possible to compare bottles on paper without claiming to have tested them ourselves. This page puts two mug ranges side by side using only the makers’ own specification pages: Zojirushi SM-ZB and Tiger MKA-K. It then explains what the numbers can and cannot tell you. We have not used or measured these bottles. Nothing here is a hands-on review.

How the makers measure “heat retention”

Both makers define their figures in the same way. At a room temperature of 20°C ±2°C, the bottle is filled with hot water and stood upright. The figure is the water temperature 6 hours after it was 95°C ±1°C (heat retention). For cold retention, it is the temperature 6 hours after the water was 4°C ±1°C. Because the conditions match, the 6-hour figures below can be compared with each other. The two makers word their filling instructions slightly differently: Zojirushi fills “to the level shown in the manual”, while Tiger’s page says the bottle is filled with hot water.

Specification comparison (makers’ figures)

What the numbers show

• Same capacity, 0.48 L: Zojirushi’s SM-ZB48 is rated at 71°C after 6 hours and Tiger’s MKA-K048 at 67°C, a 4°C difference in the makers’ ratings. Their cold-retention ratings are the same (8°C or below). Tiger’s is lighter (about 0.20 kg vs 0.23 kg), with a slightly wider mouth (4.3 cm vs 4 cm).
• Bigger keeps heat longer: within each maker’s range, the larger bottle has the higher heat-retention rating. Zojirushi goes from 66°C (0.36 L) to 71°C (0.48 L); Tiger from 67°C (0.48 L) to 70°C (0.6 L). When you compare brands, compare the same capacity.
• The lids are different designs: a one-piece stopper with no separate gasket (Zojirushi) against a one-push flip lid with a removable mouthpiece (Tiger). Which suits you depends on whether you drink with one hand while moving, or care more about fewer parts to wash. The specifications cannot decide that for you.
• “Japanese brand” does not mean “made in Japan”: Tiger’s specification table lists China as the country of production for the MKA-K. Check the product page or packaging if the origin matters to you.

What is not compared, and why

We also looked at Thermos (Japan) mugs. The 0.5 L Thermos JOK-500 page lists its own figures (69°C or above after 6 hours, 10°C or below cold) under a similar test description, but the page marks every colour as discontinued. We could not retrieve a current equivalent’s specification page, so Thermos is not in the table. The ratings are minimum guarantees under test conditions, not measurements of how a bottle performs after years of use. We have not measured that.

Background: Osaka and the vacuum-bottle industry

According to the Osaka Convention & Tourism Bureau, vacuum bottles were first imported into Japan in 1908 and first made domestically in 1912. Osaka’s glass and light-bulb craftsmen helped the industry grow there, and at the 1937 peak about 90% of Japanese-made vacuum bottles were exported. Zojirushi’s official history dates its own vacuum-bottle manufacture to 1923, the year it adopted its elephant trademark.

Correction

Earlier versions of this article were titled “Why Japanese Thermoses Are Superior” and stated that Zojirushi made Japan’s first glass-lined vacuum bottle in 1918. Neither claim was supported. The article now compares published specifications only.

Sources

• Zojirushi — SM-ZB36/48 product page and specifications (checked 2026-10-03)
• Tiger Corporation — MKA-K048/K060 product page and specifications (checked 2026-10-03)
• Thermos — JOK-500 product page (marked discontinued)
• Osaka Convention & Tourism Bureau — The history and technology of Zojirushi · Zojirushi — History

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