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Samsung Galaxy S21 5G (Exynos) Battery test: Good charge-up efficiency

This device has been retested in the latest version of our protocol. Overall, sub-scores and attributes are up to date. For detailed information, check the What’s New article

Released in January 2021 at a price that places it in the Premium segment ($600-$799), the Samsung Galaxy S21 5G (Exynos) comes with a triple-camera setup and stereo speakers, among other attractive features. Let’s take a look at how its battery performed in our DXOMARK Battery protocol tests.

Key specifications:

  • Battery capacity: 4000 mAh
  • 25W (charger not included)
  • 6.2-inch, 1080 x 2400, 120 Hz OLED display
  • Exynos 2100 (5 nm) chipset
  • Tested RAM / storage combination: 8 GB + 128 GB

About DXOMARK Battery tests: For scoring and analysis in our smartphone battery reviews, DXOMARK engineers perform a variety of objective tests over a week-long period both indoors and outdoors. This article highlights the most important results of our testing. (See our introductory and how we test articles for more details about our smartphone Battery protocol.)

Test summary


Sub-scores and attributes included in the calculations of the global score.

Samsung Galaxy S21 5G (Exynos)














Key performances

Charging Time
1 day 22h
Battery life
Charging Time
80% Charging time
Charging Time
Full charging time
Quick Boost
2h28 autonomy
after 5-minute charge
Please be aware that beyond this point, we have not modified the initial test results. While data and products remain fully comparable, you might encounter mentions and references to the previous scores.


  • Decent efficiency, especially charge up
  • Supports wireless charging


  • Despite smaller battery, slower charging speed than competition

The Samsung Galaxy S21 5G (Exynos) smartphone comes with a smaller battery and a slower charger than the two Premium devices used for comparison in this review, the Xiaomi Mi 11 and the Oppo Find X3 Neo. The table below shows the battery capacity, charger, display type and resolution, and processor specifications for the three devices.

 Samsung Galaxy S21 (Exynos)

Xiaomi Mi 11 Oppo Find X3 Neo
Battery capacity (mAh)


4600 4500


55W 65W
Wireless charging




Display type, max Hz



Display resolution

1080 x 2400 1440 x 3200

1080 x 2400


Exynos 2100 Qualcomm Snapdragon 888 5G

Qualcomm Snapdragon 865 5G

Autonomy (51)

How long a battery charge lasts depends not only on battery capacity, but also other aspects of the phone’s hardware and software. The DXOMARK Battery autonomy score is composed of three performance sub-scores: (1) Stationary, (2) On the go, and (3) Calibrated use cases. Each sub-score comprises the results of a comprehensive range of tests for measuring autonomy in all kinds of real-life scenarios.

Light Usage
Light Usage
Active: 2h30/day
Moderate Usage
Moderate Usage
Active: 4h/day
Intense Usage
Intense Usage
Active: 7h/day

The overall autonomy score for the Exynos version of the Samsung Galaxy S21 5G places it between the Xiaomi Mi 11 (36) and the Oppo Find X3 Neo (60). The Samsung provides relatively good autonomy despite its small 4000 mAh battery, while the Xiaomi struggles with a more power-consuming QHD+ display.


Samsung Galaxy S21 5G (Exynos)



Vivo Y72 5G
Best: Vivo Y72 5G (104)

A robot housed in a Faraday cage performs a set of touch-based user actions during what we call our “typical usage scenario” (TUS) — making calls, video streaming, etc. — 4 hours of active use over the course of a 16-hour period, plus 8 hours of “sleep.” The robot repeats this set of actions every day until the device runs out of power. 

Lasting 51 hours 27 minutes in our TUS tests, the Samsung Galaxy S21 5G (Exynos) lands in the bottom quarter of the DXOMARK database. While it is still ahead of the Xiaomi Mi 11, the Oppo lasts 7 hours 30 minutes longer.

Typical Usage Scenario discharge curves

On the go

Samsung Galaxy S21 5G (Exynos)



Samsung Galaxy M51
Best: Samsung Galaxy M51 (96)

Using a smartphone on the go takes a toll on autonomy because of extra “hidden” demands, such as the continuous signaling associated with cellphone network selection, for example. DXOMARK Battery experts take the phone outside and perform a precisely defined set of activities while following the same three-hour travel itinerary for each device.

The Samsung device goes head to head with the Oppo Find X3 Neo in all mobility use cases, and both the Samsung and the Oppo perform slightly better than the Xiaomi Mi 11.

Autonomy for on the go use cases (full charge)


Samsung Galaxy S21 5G (Exynos)



Samsung Galaxy M51
Best: Samsung Galaxy M51 (100)

For this series of tests, the smartphone returns to the Faraday cage and our robots repeatedly perform actions linked to one specific use case (such as gaming, video streaming, etc.) at a time. Starting from an 80% charge, all devices are tested until they have expended at least 5% of their battery power.

While the performance of the Exynos version of the Galaxy S21 5G for gaming and for video and music streaming via 4G was disappointing, the device did a good job for both video streaming via WiFi and video playback. But the Oppo Find X3 Neo had better autonomy in all calibrated use cases.

Autonomy for calibrated use cases (full charge)

Charging (73)

The DXOMARK Battery charging score is composed of two sub-scores, Full charge and Quick boost. Full charge tests assess the reliability of the battery power gauge; measure how long it takes to charge a battery from 0% to 80% capacity and from 80% to 100%; and measure how long and how much power the battery takes to go from an indicated 100% to an actual full charge. With the phone at different charge levels (20%, 40%, 60%, 80%), Quick boost tests measure the amount of charge the battery receives after being plugged in for 5 minutes. 

in 30 min
0 - 80%
Full charge
in 30 min
0 - 80%
Full charge

The S21 5G (Exynos)’s charging performance is average among all devices tested, but its rivals do better, especially the Oppo Find X3 Neo, one of the top scorers for this attribute to date.

Power consumption and battery level during full charge
Power consumption and battery level during wireless full charge

Full charge

Samsung Galaxy S21 5G (Exynos)



Black Shark 5 Pro
Best: Black Shark 5 Pro (121)

It takes the Samsung Galaxy S21 5G (Exynos) 48 minutes to go from 0 to an 80% charge, which is good. However, the Xiaomi Mi 11 takes just 30 minutes to achieve the same charge, and the Find X3 Neo takes even less time — only 23 minutes.

Time to full charge
Time to full charge

Quick boost

Samsung Galaxy S21 5G (Exynos)



Realme GT Neo 3
Best: Realme GT Neo 3 (111)

Users can expect only 2 hours 30 minutes of additional battery life after charging the Samsung Galaxy S21 5G (Exynos) for 5 minutes with 20% power remaining, which is a poor showing when compared to the Oppo Find X3 Neo in particular.

Samsung Galaxy S21 5G (Exynos) Xiaomi Mi 11 Oppo Find X3 Neo
Autonomy boost (hh:mm) 20%2:33 2:52 8:20
40%2:36 3:09 6:26
60%2:05 2:54 5:29
80%2:01 1:51 4:14
Percentage boost 20%7.4 %11.2 %22.1 %
40%7.6 %12.3 %17 %
60%6.1 %11.3 %14.5 %
80%5.9 %7.3 %11.2 %
Energy consumed 20%1458 mWh2674 mWh4712 mWh
40%1487 mWh2945 mWh3637 mWh
60%1192 mWh2709 mWh3103 mWh
80%1148 mWh1735 mWh2399 mWh

Efficiency (75)

Our Efficiency score comprises two sub-scores, Charge up and Discharge. Charge up is the efficiency of a full charge (how much energy is drained from the wall outlet vs the energy capacity of the battery, as well as the efficiency of the charger and its residual consumption). Discharge is how much current the smartphone drains from the battery when in use (the ratio of battery capacity to autonomy). Better autonomy with a smaller battery means better efficiency.

The Samsung Galaxy S21 5G (Exynos) posts an average overall score in our Efficiency testing. Among its rivals, it is far ahead of the Xiaomi (46) but behind the Oppo (87).

Charge up

Samsung Galaxy S21 5G (Exynos)



Nubia RedMagic 7 Pro
Best: Nubia RedMagic 7 Pro (105)

The Samsung Galaxy S21 5G (Exynos)’s adapter is very efficient and consumes almost nothing (just 11 mW) when the phone is detached. By contrast, however, users should unplug the Samsung’s wireless charger when not in use.


Samsung Galaxy S21 5G (Exynos)



Apple iPhone 13 Pro
Best: Apple iPhone 13 Pro (121)

The Samsung device lands between the Xiaomi (46) and the Oppo (85) for discharge efficiency, and despite its relatively small battery capacity (4000 mAh), it offers decent autonomy.


The Samsung Galaxy S21 5G (Exynos) is a well-built device, which is reflected in its decent scores for efficiency. While it lands in the bottom half of our database among all devices tested to date, it is well within the norms for Premium segment devices. The Xiaomi and Oppo smartphones have much better charging times compared to the S21 5G, but the Samsung device’s charging is nonetheless very efficient.

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