How do I know my battery size?
On most devices, battery size is listed as capacity (mAh or Wh) and, for some products, the physical size (like car-battery group size). You can usually locate this information on the battery itself or in the manufacturer’s specifications; if the battery isn’t removable, use built‑in system reports or the product page to verify.
Understanding what "battery size" means
Battery size can refer to two things: the electrical capacity, which determines how long a device runs between charges, and the physical size or form factor that ensures a replacement fits. Capacity is commonly shown in milliampere-hours (mAh) for small devices or watt-hours (Wh) for larger packs, while car batteries use ampere-hours (Ah) and a group size label rather than mAh on the label. Voltage is also a factor; most consumer lithium‑ion batteries run at around 3.6–3.9 V per cell, but the device’s pack voltage is fixed by design.
To systematically find the size across devices, follow these steps:
- Identify your device type and whether the battery is removable. If you can physically take it out, you’ll find the label directly on the battery core.
- Look for the battery label. Check for entries like "Capacity," "mAh," "Wh," or "Voltage." For cars, look for "Group Size" and "CCA" on the top or label of the cell.
- Check the device’s settings or product page. Smartphones and tablets sometimes list the design capacity or refer to official specs. Laptops use design/full charge capacity in system reports.
- Generate a battery report on a computer. On Windows, run powercfg /batteryreport; on macOS, open System Information > Power; on Linux, check upower or similar tooling.
- Review documentation or packaging. The original box or manual often lists the battery’s capacity and model number used to search for exact specs.
- If you must replace, match the capacity and the physical size. For built-in batteries, rely on the exact model number from the device’s service menu or manufacturer’s replacement parts.
- For cars, select a battery by group size, ensuring fit and performance (CCA, RC, and Ah) match the vehicle’s requirements.
Following these steps will help you identify the correct size for a replacement or for apples-to-apples comparisons when shopping.
Device-specific methods to locate battery size
Different devices have different paths to the size. The following subsections outline common methods for major categories.
Smartphones and tablets
For phones and tablets, start with the device’s official specs page. If the battery is user-removable, you’ll find a label on the battery itself with capacity (mAh or Wh) and voltage. On many newer devices with non-removable batteries, the manufacturer may not publish exact mAh; you can rely on official specs or use a third-party app to estimate capacity.
Before relying on a list, check these approaches in order:
- Check the packaging or product page for battery capacity (mAh or Wh).
- Look in the device’s Settings menu for battery information or health (varies by OS and model).
- For removable batteries, physically inspect the label on the battery itself.
- If needed, consult the manufacturer’s support site or contact customer service for the exact specification.
Understanding the capacity helps you estimate runtime and compare replacement options for mobile devices.
Laptops and desktop batteries
Laptops most commonly report design capacity and current full charge capacity in system reports. Desktops with internal UPS units follow similar principles for the battery pack. If you can access the battery physically, you’ll see the label with capacity, voltage, and sometimes model numbers.
To locate it efficiently:
- Open the system’s power management or battery report feature (Windows: powercfg /batteryreport; macOS: System Information > Power).
- Read the label on the battery if it is accessible; note design capacity and full charge capacity.
- Cross-check the laptop’s official specifications page using the exact model number.
- For replacements, match both the capacity figures and the physical connector/size as specified by the manufacturer.
Accurate battery sizing ensures compatibility and preserves warranty coverage when replacing a laptop battery.
Vehicle batteries
Car batteries use group size (a code like Group 24, 95D, or H6) and ratings such as Cold Cranking Amps (CCA) and Reserve Capacity (RC). The group size is the primary factor in fit, while CCA and Ah/RC determine performance in cold starts and endurance.
How to identify the right battery for your car:
- Check the current battery’s label for group size, CCA, RC, and Ah; the label is usually on the top or side.
- Consult the vehicle’s owner manual or manufacturer’s site for the required group size and minimum CCA.
- Bring the old battery or its label to an auto parts store to confirm fit and specifications.
- Confirm terminal orientation and venting requirements if your vehicle has special needs.
Choosing the correct group size and performance ratings ensures proper fit and reliable starting power, especially in extreme temperatures.
Interpreting numbers and practical considerations
Once you have the numbers, here is how to read them and what they mean for real-world use.
- mAh vs Wh: mAh measures capacity at a given voltage; Wh accounts for voltage and is easier to compare across devices. Wh = (mAh) × (Voltage) ÷ 1000.
- Design Capacity vs Full Charge Capacity: Design capacity is the original capacity; full charge capacity is what the battery can currently hold. A decreasing full charge capacity indicates wear.
- Voltage: The nominal voltage is typically listed on the battery label and affects how capacity translates to energy. In multi-cell packs, the overall pack voltage is determined by the series arrangement.
- Replacement matching: For most devices, you need to match both energy (Wh) and physical size/connector type. In cars, match the group size and CCA/Ah to the vehicle’s requirements.
- Practical impact: Higher Wh or Ah generally means longer runtime between charges, but real-world performance also depends on how aggressively the device uses power.
Understanding these metrics helps you compare options, estimate run time, and choose safe, compatible replacements across devices.
Summary
- Battery size is usually shown as capacity (mAh or Wh) and sometimes a physical size or group label, depending on the device.
- Use the battery label, device packaging/specs, and system reports to find the exact numbers.
- For smartphones and tablets, exact mAh may not always be published; rely on official specs or third-party estimates if needed.
- For laptops, check design vs full charge capacity in system tools; for cars, prioritize group size and CCA/Ah.
- Always verify compatibility before purchasing a replacement to ensure proper fit, safety, and performance.
By following these steps and understanding the numbers, you can accurately determine your battery size and choose the right replacement or upgrade with confidence.
Where to check battery size?
You can typically find these sizing numbers printed somewhere on your car battery or in the vehicle manual. In addition, the batteries are grouped into sizes based on their length, width and height in millimetres.
How do I tell what size battery I have?
Check the Owner's Manual: The battery section of your car's manual will list the recommended BCI Group Size and minimum CCA. Look at the Existing Battery: The current battery's Group Size is often labeled on the top label or front of the battery.
What does a 20000mAh battery mean?
20,000 mAh (milliampere-hours) means the power bank has an energy storage capacity of 20,000 milliampere-hours, which is a measure of how much electrical charge it can hold and deliver. This indicates it can supply 20,000 mA of current for one hour, and the higher the number, the more charging power it has, allowing it to charge devices multiple times before needing to be recharged. A 20,000 mAh power bank is ideal for multi-day trips or charging energy-intensive devices like laptops.
What a 20,000 mAh power bank can do
- Multiple charges: It can provide approximately 5-6 full charges for a smartphone with a 4,000 mAh battery, according to pisentech.
- Power-hungry devices: It can charge more power-hungry devices, such as tablets or even some laptops, multiple times over.
- Simultaneous charging: Some models can charge multiple devices at the same time, for example, a MacBook Pro and an iPhone.
Important considerations
- Actual usable capacity is lower: Due to energy loss during charging and voltage conversion, the actual usable capacity is typically around 60-70% of the labeled amount.
- Portability: 20,000 mAh power banks are larger and heavier than smaller capacity models, so they are less portable.
- Comparison: For perspective, a 10,000 mAh power bank is often the standard for daily use, offering about two full smartphone charges, while a 20,000 mAh model is built for longer periods away from an outlet.
How do I know my phone battery size?
Information option in the settings. You can always just search for battery. Information on the homepage of the settings. And so that is how to check your devices battery capacity in milliamp.
