1.3-Inch OLED Display Size: A Complete Technical Reference for Dimensions, Resolutions, and Use Cases

The 1.3-inch OLED display has become a cornerstone of compact electronic devices, leveraging OLED’s inherent advantages—deep blacks, vibrant colors, and thin form factors—to power products like smartwatches, fitness trackers, portable media players, and industrial sensors. While the “1.3-inch” label denotes its diagonal size, understanding its physical dimensions (in both inches and centimeters), aspect ratio nuances, and resolution capabilities is critical for engineers, product designers, and consumers alike.

Unlike LCDs, OLED displays have no backlight, allowing for ultra-thin profiles and flexible designs—traits that make the 1.3-inch size ideal for wearable tech and miniaturized devices. This guide demystifies everything about 1.3-inch OLED display sizes: from fundamental size conversions and aspect ratio breakdowns to resolution and pixel density, and real-world device examples. Whether you’re designing a wearable, selecting a replacement display, or simply curious about the technicalities of small-screen OLEDs, this resource equips you with precise, practical knowledge.

Before exploring OLED-specific traits, it’s essential to master the fundamental size metrics of a 1.3-inch display—including its diagonal length in both inches and centimeters, and why diagonal measurement is the industry standard. This section clarifies key conversions and addresses common misconceptions.

Screen size (including 1.3-inch OLED displays) is universally measured by the diagonal length of the active display panel (the area that emits light), excluding bezels. The conversion between inches and centimeters follows an internationally recognized standard:

1 inch = 2.54 centimeters

To calculate the centimeter equivalent of a 1.3-inch OLED display:

1.3 inches × 2.54 cm/inch = 3.302 centimeters

This means a 1.3-inch OLED display has a diagonal length of approximately 3.30 cm (or 33.02 millimeters). This compact diagonal size is what makes 1.3-inch OLEDs ideal for devices where space is at a premium—such as smartwatch watch faces or fitness tracker screens.

The diagonal measurement system was adopted by display manufacturers for two critical reasons:

• Consistency Across Aspect Ratios: A 1.3-inch OLED display can have different width and height dimensions (e.g., 16:9 vs. 1:1), but its diagonal length remains constant. This allows for easy comparison between devices with varying screen shapes.
• Practicality for Small Screens: For compact displays like 1.3-inch OLEDs, measuring diagonally provides a more intuitive sense of overall size than width or height alone. For example, a 1.3-inch square (1:1) OLED and a 1.3-inch widescreen (16:9) OLED serve different purposes, but their diagonal size quickly communicates their overall footprint.

• Myth 1: “1.3 inches = 3.30 cm width/height”: No—3.30 cm is the diagonal length, not the width or height. A 1.3-inch OLED’s width and height depend on its aspect ratio (see Section 2 for calculations).
• Myth 2: “Bezels are included in the 1.3-inch measurement”: No—manufacturers only measure the active OLED panel, not the surrounding bezel. For example, a smartwatch with a 1.3-inch OLED may have an overall case size of 40mm, but the display itself is 33.02mm diagonally.
• Myth 3: “All 1.3-inch OLEDs have the same physical size”: While all 1.3-inch OLEDs share a 3.30 cm diagonal, their width and height vary by aspect ratio. A 1:1 (square) 1.3-inch OLED is shorter and wider than a 16:9 (widescreen) variant.

The aspect ratio of a 1.3-inch OLED display—its width-to-height proportional relationship—defines its physical dimensions (width × height) in both inches and centimeters. This is critical for device design, as different aspect ratios suit different use cases: square ratios (1:1) for smartwatch faces, widescreen ratios (16:9) for media playback, and rectangular ratios (3:2) for fitness trackers. Below is a detailed breakdown of the most common aspect ratios for 1.3-inch OLEDs.

To find a 1.3-inch OLED’s width (W) and height (H), use the Pythagorean theorem, which relates the diagonal (D = 1.3 inches = 3.30 cm) to the aspect ratio (W:H = a:b):

1. Let width = a × x and height = b × x (where x is a scaling factor).
2. By the Pythagorean theorem: (a×x)² + (b×x)² = D²
3. Solve for x: x = D / √(a² + b²)
4. Calculate width = a × x and height = b × x

We’ll apply this formula to the four most common aspect ratios for 1.3-inch OLED displays.

The 1:1 (square) aspect ratio is the most common for 1.3-inch OLEDs, used in smartwatches and small industrial displays. Its balanced shape is ideal for displaying watch faces, notifications, and circular UI elements.

• Aspect ratio: a = 1, b = 1
• x = 1.3 inches / √(1² + 1²) = 1.3 / √2 ≈ 1.3 / 1.414 ≈ 0.919 inches
• Width: 1 × 0.919 ≈ 0.92 inches (≈ 2.34 cm, since 0.92 × 2.54 ≈ 2.34)
• Height: 1 × 0.919 ≈ 0.92 inches (≈ 2.34 cm)

• Physical dimensions (approx.): 0.92 × 0.92 inches (2.34 × 2.34 cm)
• Pixel resolution examples: 360×360, 400×400 (common in smartwatches)
• Ideal use cases: Smartwatch watch faces, circular UI displays, small industrial control panels
• OLED Advantage: Square 1.3-inch OLEDs excel at showing crisp watch hands and notifications, with OLED’s deep blacks making text (e.g., time, date) stand out against dark backgrounds.
• Common Devices: Entry-level to mid-range smartwatches, portable digital thermometers, small medical monitors.

The 16:9 (widescreen) aspect ratio is used in 1.3-inch OLEDs designed for media playback—such as portable MP3 players or miniaturized video cameras. It prioritizes horizontal space for videos and wide UI layouts.

• Aspect ratio: a = 16, b = 9
• x = 1.3 inches / √(16² + 9²) = 1.3 / √(256 + 81) = 1.3 / √337 ≈ 1.3 / 18.357 ≈ 0.0708 inches
• Width: 16 × 0.0708 ≈ 1.13 inches (≈ 2.87 cm, since 1.13 × 2.54 ≈ 2.87)
• Height: 9 × 0.0708 ≈ 0.64 inches (≈ 1.63 cm)

• Physical dimensions (approx.): 1.13 × 0.64 inches (2.87 × 1.63 cm)
• Pixel resolution examples: 480×270, 640×360 (720p scaled down)
• Ideal use cases: Portable media players, mini video cameras, small in-car infotainment screens
• OLED Advantage: 16:9 1.3-inch OLEDs deliver vibrant, wide-color gamut videos, with OLED’s pixel-level dimming eliminating backlight bleed (a common issue in small LCDs).
• Common Devices: Compact MP3/MP4 players, wearable action cameras, small GPS modules for drones.

The 3:2 (rectangular) aspect ratio balances width and height, used in 1.3-inch OLEDs for fitness trackers and productivity-focused wearables. It offers more vertical space than 16:9, making it ideal for displaying long text (e.g., workout summaries) or vertical UI elements.

• Aspect ratio: a = 3, b = 2
• x = 1.3 inches / √(3² + 2²) = 1.3 / √(9 + 4) = 1.3 / √13 ≈ 1.3 / 3.605 ≈ 0.3606 inches
• Width: 3 × 0.3606 ≈ 1.08 inches (≈ 2.74 cm, since 1.08 × 2.54 ≈ 2.74)
• Height: 2 × 0.3606 ≈ 0.72 inches (≈ 1.83 cm)

• Physical dimensions (approx.): 1.08 × 0.72 inches (2.74 × 1.83 cm)
• Pixel resolution examples: 320×213, 480×320
• Ideal use cases: Fitness trackers (displaying step counts, heart rate graphs), small e-readers, portable productivity devices
• OLED Advantage: 3:2 1.3-inch OLEDs use less power than LCDs when displaying text (OLEDs only illuminate pixels needed for text, not the entire screen), extending battery life in wearables.
• Common Devices: Mid-range fitness trackers, small e-book readers, portable note-taking devices.

The 4:3 (legacy rectangular) aspect ratio is less common in modern 1.3-inch OLEDs but still used in specialized devices like industrial sensors and legacy medical monitors. It offers more vertical space than 16:9, making it suitable for displaying tabular data.

• Aspect ratio: a = 4, b = 3
• x = 1.3 inches / √(4² + 3²) = 1.3 / √(16 + 9) = 1.3 / 5 = 0.26 inches
• Width: 4 × 0.26 = 1.04 inches (≈ 2.64 cm, since 1.04 × 2.54 ≈ 2.64)
• Height: 3 × 0.26 = 0.78 inches (≈ 1.98 cm)

• Physical dimensions (exact): 1.04 × 0.78 inches (2.64 × 1.98 cm)
• Pixel resolution examples: 320×240, 480×360
• Ideal use cases: Industrial sensors (displaying temperature/pressure readings), legacy medical monitors, retro gaming devices
• OLED Advantage: 4:3 1.3-inch OLEDs retain compatibility with legacy software designed for 4:3 LCDs, while offering better contrast and lower power consumption.
• Common Devices: Industrial IoT sensors, legacy wearable medical monitors, retro handheld gaming consoles.

A 1.3-inch OLED’s clarity and usability depend on its resolution (number of pixels) and pixel density (pixels per inch, PPI)—metrics that are even more critical for small screens, where low pixel density can make text and icons appear pixelated. This section explains how resolution interacts with 1.3-inch OLEDs, why pixel density matters, and which resolutions are ideal for different use cases.

• Resolution: The total number of pixels on the OLED panel, expressed as width × height (e.g., 360×360). Higher resolution means more pixels, translating to sharper images—especially important for small screens like 1.3-inch OLEDs.
• Pixel Density (PPI): The number of pixels per inch of screen space, calculated as:

PPI = √(width pixels² + height pixels²) / diagonal inches (1.3)

For 1.3-inch OLEDs, PPI is a make-or-break metric: values below 300 PPI may result in visible pixels, while values above 300 PPI (often called “Retina” density) make pixels indistinguishable to the naked eye.

• Pixels Per Centimeter (PPCM): Useful for global design, calculated by dividing PPI by 2.54 (e.g., 300 PPI ≈ 118 PPCM).

Below are the most common resolutions for 1.3-inch OLED displays, along with their PPI, PPCM, and ideal use cases:

• PPI Calculation: √(320² + 320²) / 1.3 = √(102,400 + 102,400) / 1.3 = √204,800 / 1.3 ≈ 452.5 / 1.3 ≈ 348 PPI
• PPCM: ~137 PPCM (348 / 2.54 ≈ 137)
• Clarity: Sharp enough for smartwatch use—pixels are barely visible, even when viewed up close (6–12 inches away).
• Ideal Use Cases: Entry-level to mid-range smartwatches, small fitness trackers with square displays
• OLED Advantage: 320×320 1.3-inch OLEDs balance clarity and power efficiency—they’re sharp enough for watch faces but don’t require the high power draw of 400×400 resolutions.
• Example Use: A smartwatch using this resolution can display a crisp analog watch face with readable time, date, and step count.
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• PPI Calculation: √(360² + 360²) / 1.3 = √(129,600 + 129,600) / 1.3 = √259,200 / 1.3 ≈ 509.1 / 1.3 ≈ 391.6 PPI
• PPCM: ~154 PPCM (391.6 / 2.54 ≈ 154)
• Clarity: “Retina-like” density—pixels are indistinguishable to the naked eye at normal viewing distances (6+ inches).
• Ideal Use Cases: Mid-range to high-end smartwatches, premium fitness trackers
• **OLED