Photo: Samsung · source ↗Manufacturer device image for this battery profile — not a removed battery.

Phone battery capacity

Samsung

Galaxy S25 Ultra

Samsung's 2025 Ultra retains the same sourced rated energy as the S24 Ultra, so power-bank charge estimates remain almost unchanged.

Direct answer

The Galaxy S25 Ultra battery stores 18.84 watt-hours.

The model-specific battery source lists 18.84Wh, 4,855mAh and a separately published typical value of 5,000mAh. Nominal voltage is 3.88V. This technical record says nothing about an Irish retailer, euro price or warranty.

Rated energy: 18.84Wh
Rated capacity: 4,855mAh
Typical capacity: 5,000mAh
Nominal voltage: 3.88V

Power-bank calculation

How many full charges?

We take 75% of the power bank’s rated Wh and divide it by this phone’s 18.84Wh. This is a planning estimate, not a charging guarantee.

5,000mAh class≈ 0.7×

18.5Wh rated → 13.9Wh planned delivery

10,000mAh class≈ 1.5×

37Wh rated → 27.8Wh planned delivery

20,000mAh class≈ 2.9×

74Wh rated → 55.5Wh planned delivery

(power-bank Wh × 0.75) ÷ 18.84Wh

Capacity is not speed

18.84Wh tells you how much.
Charging power tells you how fast.

Wired chargingUp to 45W wired charging with a compatible 5A USB-C cable and adapter

The phone, USB power adapter and cable must negotiate a compatible charging profile. Use certified equipment suitable for the Irish 230V supply.

Wireless chargingFast Wireless Charging 2.0 and Wireless PowerShare

Alignment, heat and charger certification affect real charging power.

Evidence

Two sources with different jobs.

The manufacturer supports the phone and charging claims. The model-specific battery source supplies the figures used in the calculation. These technical figures do not prove Irish retail availability or an included charger.

Manufacturer specificationSamsung specifications ↗Model-specific battery evidenceBattery data via iFixit ↗Sources checked 2026-08-21. We have not physically tested this phone.

Frequently asked

Keep energy and charging power separate.

How many Wh is the Samsung Galaxy S25 Ultra battery?

The model-specific source lists 18.84Wh and 4,855mAh. Watt-hours are the useful figure when comparing it with a power bank.

How many times can a 10,000mAh power bank charge the Galaxy S25 Ultra?

A power bank rated around 37Wh provides about 1.5 full charges in this planning calculation. We assume 75% of rated energy reaches the phone battery; actual results vary with cable, temperature and use while charging.

Does 18.84Wh mean the phone charges at 18.84W?

No. 18.84Wh is stored energy. Charging power is a rate measured in watts; the sourced charging description for this model is Up to 45W wired charging with a compatible 5A USB-C cable and adapter.