Battery Size Chart

Battery Size Chart: The Complete Guide to All Your Battery Dimensions

Finding the right battery is never just about voltage or capacity—it starts with the physical dimensions. If a battery is a millimeter too wide, a fraction too thick, or the wrong shape altogether, it simply will not fit, and no amount of technical specification can rescue a dimensional mismatch.

This guide breaks down dimension conventions across six major battery categories we carry at OneAndes—Cylindrical Batteries, AA/AAA & Specialty Batteries, Prismatic LiFePO4 Batteries, Polymer Lithium-ion Batteries, Coin Button Batteries, and LiFePO4 Battery Packs & Modules—so you can skip the guesswork and pick the right power source the first time around.

If you are looking for a broader overview of the product families we carry, our product catalog organizes everything by chemistry, form factor, and application. For those who want to dig deeper into specific cell comparisons, we have a detailed article breaking down the differences between the two most popular cylindrical formats in our 18650 vs 21700: The Ultimate Comparison Guide.

1. Cylindrical Batteries: The Industry Workhorse

Cylindrical lithium-ion batteries are ubiquitous. From laptop battery packs to Tesla’s vehicle floorpans, their standardized naming convention makes size identification refreshingly straightforward. The five-digit model number encodes the approximate physical dimensions: the first two digits denote the diameter in millimeters, the next two denote the length in millimeters, and the trailing zero signals the cylindrical form factor.

Here is the core dimensional reference for the most common cylindrical lithium-ion cells:

The jump from one format to the next involves more than just numbers. The 21700 cell, for instance, offers roughly 20% higher volumetric energy density compared to the 18650 when comparing the same cathode chemistry. The 4680 cell takes this scaling logic to its extreme: its volume is approximately 704% that of an 18650, with a corresponding leap in nominal energy per cell.

For a thorough side-by-side breakdown of how these two formats compare in real-world applications, our 18650 vs 21700 Ultimate Comparison Guide covers energy density, heat dissipation, and device compatibility in depth.

Beyond the headline dimensions, there are practical nuances to keep in mind. Protected cells—those with a built-in protection circuit board (PCB)—add roughly 2–3 mm to the length and a fraction of a millimeter to the diameter. A protected 18650 can measure closer to 68–70 mm long, which may prevent it from fitting into a spring-loaded flashlight or a tight charger bay designed for bare 65 mm cells. Similarly, button-top cells (with a protruding positive terminal) can be 1–3 mm longer than flat-top equivalents. Always check your device’s specification for the maximum allowable cell length.

2. AA/AAA & Specialty Batteries: Standard Sizes, Different Chemistries

Standard consumer alkaline and NiMH sizes (AA: 14×50 mm, AAA: 10.5×44.5 mm, C: 26.2×50 mm, D: 33.2×61.5 mm) share similar or identical diameters to some lithium formats but operate at 1.5V and 1.2V respectively. They are generally not interchangeable without a device designed for both voltage ranges.

3. Prismatic LiFePO4 Batteries: Rectangular Power for Deep-Cycle Applications

Prismatic cells are the format of choice for applications that demand high capacity in a space-efficient rectangular package. Instead of a rigid steel can, they use a flat aluminum or steel enclosure that stacks internal electrode layers, maximizing volume utilization. In the LiFePO4 space, prismatic cells dominate solar energy storage, marine house banks, electric forklifts, and low-speed vehicles precisely because their geometry packs neatly into rack-mount frames and compartmentalized enclosures.

Prismatic LiFePO4 cells are identified by capacity and external dimensions expressed as Thickness × Width × Height. There is no universal model-number-to-size formula as with cylindrical cells, which makes having a reference chart essential. Below is a representative survey of commercially available LiFePO4 prismatic cells across the capacity spectrum:

The dimensional variation across capacities is driven by different internal electrode designs and manufacturers’ optimization for specific applications. High-cycle variants tend to be slightly heavier per amp-hour because they use thicker electrodes that tolerate repeated expansion and contraction.

It is also worth noting that prismatic LiFePO4 cells are a core building block for assembled battery packs. When sourcing raw cells for a DIY build, always verify the terminal type (welded stud vs. bolt-on vs. laser-weldable tab) and the cell’s expected swelling allowance—prismatic cells can expand by 1–3 mm across the thickness over thousands of cycles.

4. Polymer Lithium-ion Batteries: Thin, Flexible, and Shape-Adaptable

Lithium polymer (Li-Po) batteries represent the ultimate in form-factor flexibility. Unlike cylindrical or prismatic cells encased in rigid metal shells, Li-Po cells use a soft aluminum-laminated pouch film, allowing thicknesses below 1 mm and enabling curved or irregular shapes that conform to the device housing itself.

The trade-off is mechanical robustness: pouch cells lack the structural rigidity of steel-cased cylindrical cells and must be protected from puncture, crushing, and excessive swelling. But for applications where every millimeter of device thickness counts—smartphones, tablets, Bluetooth earbuds, wearables, GPS trackers, and ultra-thin power banks—Li-Po is irreplaceable.

Li-Po cell dimensions are expressed as Thickness × Width × Length (in mm), and many manufacturers embed these numbers directly into the model code. For example, a cell labeled “503450” measures 5.0 mm thick × 34 mm wide × 50 mm long. Here is a representative sampling of standard Li-Po sizes across common capacity bands:

When selecting a Li-Po cell, pay close attention to tolerance specifications. Standard manufacturing tolerances are typically ±1 mm on length and width, and ±0.2–0.3 mm on thickness. A 0.5 mm thickness deviation may not sound like much, but in a smartphone with a designed battery cavity of 4.0 mm, a cell that arrives at an actual 4.5 mm can prevent the display from seating properly.

5. Coin Button Batteries: Small, Flat, and Standardized

Coin and button batteries follow an international naming standard that encodes chemistry, diameter, and thickness directly into the model number, making them one of the most systematically organized battery categories. The format is: chemistry prefix (two letters) + diameter code (two digits, in mm) + thickness code (two digits, expressed in tenths of a mm). For example, CR2032 breaks down as: C = Lithium chemistry, R = Round form factor, 20 = 20 mm diameter, 32 = 3.2 mm thickness.

Coin cell sizes range from approximately 4.8 mm to 30 mm in diameter and 1.0 mm to 7.7 mm in thickness, covering an enormous variety of low-power devices. Here is a practical selection of the most frequently encountered models:

The most critical point for anyone replacing a coin battery: same voltage does not mean same fit. The CR2016, CR2025, and CR2032 all share the same 20 mm diameter and 3V nominal voltage, but a device designed for a 3.2 mm-thick CR2032 will not close with a 2.5 mm-thick CR2025, and a slot made for a 1.6 mm-thick CR2016 will not accommodate the thicker model.

6. LiFePO4 Battery Packs & Modules: From Single-Cell to System-Level Dimensions

Individual LiFePO4 prismatic cells are raw components; LiFePO4 battery packs and modules are the finished, often enclosure-housed units that deliver a target system voltage—commonly 12.8V (4S), 25.6V (8S), or 48V (16S)—at a specific energy capacity. The dimensional jump from cell to pack is significant: a 48V 200 Ah module might incorporate sixteen 200 Ah cells plus bus bars, a battery management system (BMS), terminal blocks, communication ports, and a steel or heavy-duty plastic casing, all of which dramatically change the footprint.

Below are representative dimensions for LiFePO4 battery modules in different voltage and capacity classes:

When planning a pack integration, always account for the BMS board thickness (which can add 15–30 mm to one dimension) and the additional space required for cable routing, ventilation, and terminal access. For packs that will be installed in mobile applications (RVs, boats), factor in shock and vibration mounts that add further external clearance.

7. The Universal Rule: Verify Before You Buy

Across all six categories, a single rule holds: the datasheet dimension is the nominal dimension. Manufacturing tolerances, protection circuits, terminal types, and enclosure requirements all introduce real-world deviations from the printed number.

• For cylindrical cells, check whether protected or unprotected cells are specified.

• For prismatic LiFePO4 cells, confirm that the enclosure accounts for the expected swelling over the cell’s life.

• For Li-Po cells, verify the tolerance range on thickness—usually ±0.2 to 0.3 mm, which matters more than any other dimension.

• For coin cells, never substitute a thinner cell for a thicker one just because the diameter and voltage match.

• For battery packs, always leave clearance for cable routing, ventilation, and connector access.

A dimensional mismatch is the single most common source of returns and refunds in the battery industry—and it is almost entirely preventable. Take the measurement. Check the chart. Then place the order.

If you are ready to apply this guide to a real purchase, visit our product catalog for live inventory, detailed datasheets, and dimensional drawings for every battery in stock.