GB/T 38426-2019 standard: thermal testing protocol for Chinese sleeping bags and comparison with EN 13537 / ISO 23537-1
Some sleeping bags available on the market, particularly those from brands like Naturehike and other reputable Chinese manufacturers, mention the GB/T 38426-2019 standard on their label or product sheet. This reference is often unknown to European buyers, who are accustomed to EN 13537 or ISO 23537-1 ratings. Misunderstanding this standard generates two opposing reactions: either ignoring it completely, or suspecting it to be less reliable than a European standard. Neither of these reactions is well-founded.
This article explains what GB/T 38426-2019 is, what its test protocol concretely guarantees, how it compares to EN 13537 and ISO 23537-1, and how to interpret the temperatures certified on bags that carry it. To quickly identify a model suited to your use, the interactive selection tool integrates the characteristics of each bag regardless of the certification standard displayed.
What is the GB/T 38426-2019 standard?
Origin and official status
GB/T 38426-2019 is a Chinese national standard published on December 31, 2019, and effective as of July 1, 2020. Its official title is 睡袋的热阻和使用温度的测定方法, translated into English as "Test method for thermal resistance and use temperature of sleeping bags." It is administered by the National Technical Committee on Clothing (TC219), under the supervision of the China National Textile and Apparel Council.
The prefix GB/T designates a recommended national standard (推荐性国家标准), as opposed to mandatory standards (GB). This means that its application is voluntary for manufacturers: a Chinese manufacturer that chooses to have its bag certified according to this standard deliberately commits to submitting its product to an independent and documented test protocol. This voluntary choice distinguishes a certified bag from one whose temperatures are simply estimated by the manufacturer without a formalized protocol.
💡 No law requires a manufacturer to certify its bag according to a thermal standard. A bag bearing the mention GB/T 38426-2019 has undergone testing in an independent laboratory. Without mention of a standard, the temperatures are manufacturer estimates without a formalized protocol.
Scope
The standard applies to adult sleeping bags intended for sports and leisure activities, tested under stationary conditions (steady state). It explicitly excludes three categories: bags for military use, bags for expeditions in extreme conditions, and bags for children aged 14 and under. This scope is identical to that of EN 13537 and ISO 23537-1, which is a first point of consistency between the systems.
The test protocol: what the standard requires
The thermal manikin
The GB/T 38426-2019 test relies on the use of a heated thermal manikin (暖体假人 in Chinese), a calibrated measuring instrument whose surface is equipped with temperature sensors and heating resistors. This manikin simulates the heat production of a human body at rest. It is placed inside the sleeping bag to be tested, itself placed on an insulating mattress, in a controlled climate chamber (人工气候室).
The standard requires the thermal flux of the manikin to be between 20 and 120 W/m², or its surface temperature to remain between 25 and 40°C, values corresponding to the physiological thermal range of an adult human body at rest. These parameters are identical in their logic to those used by EN 13537 and ISO 23537-1, which also maintain the skin temperature of the manikin at around 34°C.
The rigor of the protocol
The standard requires stabilization in a steady state before any measurement: conditions must be stable for at least 20 consecutive minutes to validate the measurement. This stability criterion ensures that results are not biased by transient temperature fluctuations in the chamber.
The standard also requires a minimum of three independent trials per bag, each performed by re-placing the manikin in the bag from the start. The final result is the average of the three measurements. This principle of triple repetition is directly comparable to the EN 13537:2012 protocol, which also requires three tests to improve reproducibility and limit inter-laboratory variability.
⚠️ As with EN 13537 and ISO 23537-1, GB/T 38426-2019 test conditions are controlled laboratory conditions. The certified temperatures are indicators for comparing bags, not absolute guarantees of comfort in all real bivouac situations.
The temperatures produced
The GB/T 38426-2019 test produces use temperatures (使用温度) calculated from the measured thermal resistance of the bag. These temperatures include a comfort temperature and a limit temperature, whose functional definitions are comparable to those of EN 13537: the comfort temperature corresponds to the threshold of normal use for a standard adult sleeper, and the limit temperature to the threshold of discomfort without immediate physiological danger.
Positioning relative to EN 13537 and ISO 23537-1
Fundamental commonalities
The three standards share the same measurement approach: thermal manikin in a climate chamber, steady state, calculation of thermal resistance converted into use temperatures. This methodological convergence is no coincidence: the international scientific community of researchers in thermoregulation uses the same fundamental physical principles, regardless of the geographical context of the standard's publication.
The three standards apply to the same categories of bags (adults, sports, and leisure) and exclude the same categories (military, extreme expeditions, children). They all produce comfort and limit temperature values that can be used as comparison criteria between products tested according to the same standard.
Differences in context and visibility
The main difference between GB/T 38426-2019 and EN 13537 / ISO 23537-1 is not technical but geographical and commercial. EN 13537 was developed in 2002 for the European market and was quickly adopted by the majority of global manufacturers seeking to sell in Europe. ISO 23537-1, published in 2016, is its international extension. GB/T 38426-2019 is the Chinese national standard, developed by and for the Chinese textile industry, which produces the majority of sleeping bags sold worldwide.
EN 13537 and ISO 23537-1 are better known to European consumers simply because they were created for their market. GB/T 38426-2019 is less known in Europe not because it is less rigorous, but because it was published for a different market.
🚫 Do not confuse lack of awareness with lack of rigor. GB/T 38426-2019 is published by the Chinese national standardization authority (SAMR). Its regulatory framework is just as solid as that of EN 13537 in Europe.
Confirmation of compatibility: GB/T 44139.1-2024
A recent fact confirms the compatibility between the Chinese and international standard systems. In 2024, China published the GB/T 44139.1-2024 standard (effective as of January 1, 2025), which defines the thermal performance requirements for adult sleeping bags intended for limit temperatures above -20°C. This standard adopts identically (IDT, full adoption without technical modification) the ISO 23537-1:2022 standard, the most recent version of the international standard.
This deliberate choice by Chinese standardization authorities confirms two things. First, that Chinese and international test protocols are considered compatible and interchangeable in terms of results. Second, that GB/T 38426-2019 (test method) and GB/T 44139.1-2024 (performance requirements) now form a complete system that coexists with ISO 23537-1 and produces directly comparable values.
What a GB/T 38426-2019 certification concretely guarantees
What is guaranteed
A sleeping bag bearing the mention GB/T 38426-2019 on its sheet or label guarantees that the displayed temperatures were obtained through a laboratory test protocol with a calibrated thermal manikin, in a steady state, with a minimum of three independent trials. The values are not marketing estimates but documented instrumental measurements. This level of guarantee is comparable to that offered by an EN 13537 or ISO 23537-1 certification.
The Naturehike models available in the trekking collection and the 0°C collection fall within this framework: the comfort and limit temperatures indicated on the sheets correspond to values derived from laboratory test protocols, not manufacturer data without a measurement basis. The Naturehike CW700 0°C and the Naturehike MJ600 -5°C are examples of models whose sheets indicate the measured comfort and limit temperatures.
What remains to be checked individually
As with EN 13537 and ISO 23537-1, laboratory test conditions differ from actual bivouac conditions. The mattress used during the test, the manikin's clothing, and the climate chamber conditions are standardized but do not necessarily correspond to the equipment and conditions of each user. The factors that influence the perceived temperature in real conditions are the same regardless of the standard: R-value of the mattress, clothing worn inside the bag, state of fatigue, ambient humidity, and wind.
A margin of 3 to 5°C from the certified comfort temperature is still recommended for cold-sensitive sleepers, trips at altitude, or variable weather conditions, regardless of the certification standard displayed on the bag.
Comparison table of the three standards
| Criterion | EN 13537 | ISO 23537-1 | GB/T 38426-2019 |
|---|---|---|---|
| Origin | Europe (CEN), 2002 | International (ISO), 2016/2022 | China (SAMR), 2019 |
| Test method | Thermal manikin, climate chamber | Thermal manikin, climate chamber | Thermal manikin, climate chamber |
| Number of trials | 3 trials, result = average | 3 trials, result = average | Minimum 3 trials, result = average |
| Temperatures produced | Comfort / Limit / Extreme | Comfort / Limit / Extreme | Comfort / Limit |
| Scope | Adults, sports/leisure, excl. military/children | Adults, sports/leisure, excl. military/children | Adults, sports/leisure, excl. military/children ≤14 yrs |
| European recognition | Historical market reference | Current international reference | Less known, compatible with ISO |
| ISO Compatibility | Protocol identical to ISO 23537-1 | Current global reference | Compatible system, GB/T 44139.1-2024 = ISO 23537-1:2022 |
Frequently asked questions
Is a bag certified GB/T 38426-2019 as reliable as a bag certified EN 13537?
In principle, yes: both standards use a thermal manikin in a controlled climate chamber with a minimum of three independent trials. The temperatures produced are instrumental measurements, not estimates. The main difference is the commercial visibility of the standard in Europe, not its methodological rigor. The publication in 2024 of GB/T 44139.1-2024 as an identical adoption of ISO 23537-1:2022 by Chinese standardization authorities confirms the compatibility between the two systems.
Why do some Chinese manufacturers display EN 13537 rather than GB/T 38426-2019?
Because EN 13537 is better recognized in the European and North American markets. A Chinese manufacturer exporting to Europe has an interest in having its bags tested by an EN 13537-accredited laboratory to reassure local buyers. Displaying GB/T 38426-2019 instead does not mean the test is less rigorous, simply that the manufacturer has opted for the reference framework of its domestic market.
How to identify if the temperatures of a Naturehike bag are certified or estimated?
Check the product sheet to see if a test standard is explicitly mentioned (GB/T 38426-2019, EN 13537, or ISO 23537-1). If no standard mention appears, the temperatures are manufacturer estimates without an independent protocol. On the sheets of products available in the sleeping bag shop, comfort and limit temperatures are indicated with their source when a test protocol has been applied.
Does the GB/T 38426-2019 standard include an extreme temperature?
Available public sources indicate that GB/T 38426-2019 produces comfort and limit temperatures. Extreme temperature (survival threshold of 6 hours) is not systematically mentioned in accessible extracts of the standard, unlike EN 13537 and ISO 23537-1 which explicitly include it. On sheets for GB/T 38426-2019 certified bags, check whether three values or only two are indicated.
What is GB/T 44139.1-2024 and what is its relationship with GB/T 38426-2019?
GB/T 44139.1-2024, which entered into force on January 1, 2025, is the Chinese thermal performance standard for adult sleeping bags. It fully adopts ISO 23537-1:2022 (the most recent version of the international standard) and references GB/T 38426-2019 as the associated test method. These two standards work in tandem: GB/T 38426-2019 defines the measurement protocol, and GB/T 44139.1-2024 defines the performance requirements to be achieved. This system is the functional equivalent of the EN 13537 / ISO 23537-1 pair in the European market.
Conclusion
The GB/T 38426-2019 standard is the Chinese national method for thermal testing of adult sleeping bags. It relies on a heated thermal manikin in a controlled climate chamber, with a minimum of three independent trials and steady-state stabilization before each measurement. Its methodological approach converges with that of EN 13537 and ISO 23537-1: same physical principles, same type of instrument, same logic of comparison between tested products.
The lack of awareness of this standard in Europe is a matter of commercial visibility, not scientific rigor. The publication in 2025 of GB/T 44139.1-2024 as an identical adoption of ISO 23537-1:2022 by Chinese authorities confirms the compatibility of the two systems. A bag bearing the mention GB/T 38426-2019 has undergone independent laboratory testing: its temperatures are measured values, comparable in their logic to values certified EN 13537 or ISO 23537-1. The same precautions for interpretation apply in all cases: add a margin of 3 to 5°C for cold-sensitive sleepers, and check the R-value of the mattress, the primary insulation factor in real conditions. The models in the down sleeping bag and cold-weather collection available indicate their certified temperatures on each product sheet.
⚡ Verdict: GB/T 38426-2019, EN 13537, and ISO 23537-1 rely on the same principle, the laboratory thermal manikin. The displayed standard indicates the geographical origin of the test, not its level of rigor.
