How can I tell what size my battery is?
To determine the size of a battery, you’ll typically look at its capacity (measured in mAh or Wh), its voltage, and its physical dimensions. You can confirm these details by reading the battery label, checking official specifications from the manufacturer, or using diagnostic tools and reputable guides.
Whether you’re replacing a device battery, upgrading a pack, or checking compatibility, the steps vary by device type. This guide walks through practical methods for smartphones and tablets, laptops and external packs, and other common battery types, with clear steps and caveats.
Smartphones and tablets
Use these steps to identify the size and capacity of a phone or tablet battery, whether you’re shopping for a replacement or trying to understand a device’s endurance.
- Inspect the battery label if the battery is removable. The label usually lists the capacity in mAh (and sometimes Wh) along with the voltage and a model number you can look up.
- Check the device’s settings or official specs. Some Android devices show battery information in the About/Device section, while iPhones typically expose maximum battery capacity in Battery Health but not the exact mAh. When exact numbers aren’t shown, you may rely on model specifications from the manufacturer or teardown sources.
- Look up the device’s model or part number online. Searching the device’s exact model name plus “battery capacity” or “Wh” often yields the OEM’s official spec sheet or a trusted teardown reference.
- Consider a diagnostic app for an estimate. On Android, apps like AccuBattery can estimate remaining design and current capacity; on iOS, you’ll mainly rely on the model’s official specs or third-party teardown data since apps have limited access to low-level battery metrics.
In practice, you’ll often rely on a combination of the battery label, official device specifications, and credible third-party references to determine the correct replacement size. If the battery is non-removable, you’ll lean more on official specs and professional service guidance.
Laptops and external battery packs
For laptops and external packs, precise numbers matter for replacement parts and charging compatibility. The following methods cover both built-in and removable scenarios.
- Read the battery’s label or the inside view of the battery bay for design capacity and current full charge capacity if the battery is removable. Look for values expressed in mWh or mAh at a specified voltage.
- On Windows laptops, generate a battery report to see design capacity and full charge capacity. Open Command Prompt as administrator and run: powercfg /batteryreport. The report is saved to your user folder and includes the design vs. full charge capacity over time.
- On macOS laptops, open About This Mac > System Report > Power. You’ll find Design Capacity and Full Charge Capacity, along with cycle count and health status, which helps determine if an upgrade is needed.
- Consult the manufacturer’s site or the laptop’s service manual for the exact battery model number and its official specifications. If the battery is internal, you may need a service technician to confirm size and replacement options.
- For external power banks (USB-C, etc.), read the labeled capacity (in mAh). If you know the nominal cell voltage (often 3.7V), you can compute watt-hours (Wh) = (mAh × 3.7V)/1000 for a rough comparison among packs.
These steps help you verify both the electrical rating and the physical form factor so you purchase a compatible replacement or a suitable spare power source.
Other common battery types
Small cameras, handheld devices, RC vehicles, and other gadgets use a variety of battery formats. Here’s a practical approach that covers most scenarios.
- Look for the label on the battery itself, which usually lists capacity (mAh or Wh) and voltage. If the battery is not user-accessible, check the device’s manual or the manufacturer’s product page for the exact battery model and its specs.
- Match the model number to official documentation. Many devices reuse the same battery part number across lots of shipments, so the part number is your best anchor for a correct replacement.
- When replacing, verify the chemistry and voltage. A wrong chemistry (e.g., Li-ion vs. NiMH) or a voltage mismatch can damage the device or reduce performance.
By confirming the battery label, official specs, and part numbers, you’ll minimize the risk of buying the wrong size or capacity for your device.
Summary
The most reliable way to tell your battery size is to read the label on the battery itself (if accessible), then cross-check the device’s official specifications or the OEM’s replacement parts resources. For laptops and desktops, OS-based tools like Windows’ battery report or macOS System Report provide design and full-charge capacities, while smartphones often rely on model specs and health indicators. When in doubt, consult the manufacturer or a qualified technician to confirm compatibility before purchasing a replacement.
Further notes
Understanding these numbers helps with replacement decisions and with comparing power banks, chargers, and devices. Remember that “mAh” and “Wh” are measures of capacity, while voltage and chemistry determine compatibility and safety. The exact display of capacity can vary by device and operating system, so using a combination of label data and official specs yields the most accurate result.
