Mobile Dev

Android PX vs DP vs DIP vs SP: Differences & Usage

Understand the difference between px, dp (dip), and sp units in Android UI development. Learn when to use android dp for layouts, android sp for text, and px for pixels, with conversion formulas and best practices.

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What is the difference between px, dip, dp, and sp units in UI development, and when should each be used?

android dp and android sp are abstract units Android uses so your UI scales correctly: dp (aka dip) scales with screen density to keep layout elements the same physical size across devices, while sp scales with density and the user’s font-size preference for accessible text. px is a raw device pixel (absolute) and is rarely the right choice for layouts—use dp for widths, heights, margins and sp for text; use px only when you need exact bitmap or canvas pixels.

Contents

Understanding android dp (dip), android sp, and px

Start with the plain definitions.

  • px — a pixel on the actual screen. It’s an absolute unit tied to the device’s physical pixels. Use when you literally need pixel-accurate control (bitmaps, some Canvas drawing).
  • dp / dip (density-independent pixel) — an abstract unit that scales with screen density so UI elements keep roughly the same physical size across devices. On a baseline 160 dpi screen, 1 dp ≈ 1 px; on higher-density screens the system multiplies dp to get the required px. The Android docs recommend dp for layout dimensions like widths, heights, margins and padding (developer.android.com).
  • sp (scale-independent pixel) — like dp but also scaled by the user’s preferred font-size setting. Use sp for text so accessibility settings (larger fonts) are respected.

Why not just pick px and be done? Because screen densities vary wildly. A 48px button on a low-density phone looks huge on mdpi and tiny on xxhdpi. dp and sp let the system handle that scaling so controls remain usable and readable across devices (iHeavy explanation, GeeksforGeeks quick guide).

Examples in XML:

xml
<Button
 android:layout_width="120dp"
 android:layout_height="48dp"
 android:text="Tap"
 android:textSize="16sp" />

Short, practical rule: dp for layout; sp for text; px only for fixed-image or pixel-perfect drawing.

When to use android dp vs android sp vs px

Here are practical, battle-tested rules you can apply right away.

  • Use dp for:

  • Layout sizes: widths, heights, margins, padding, icon containers.

  • Touch targets and spacing so elements feel consistent on different screens.

  • Anything that should retain the same physical size across densities.

  • Example: minimum touch target ~48dp (common guideline for ergonomics).

  • Use sp for:

  • All user-visible text: TextView, Button text, EditText, captions.

  • Text that should respect the user’s font-size preference (accessibility).

  • Exception: if you need text to remain visually fixed regardless of user settings (rare), you could use dp—but avoid that for body text.

  • Use px for:

  • Bitmaps and raw image pixel operations—when you’re working with the image’s pixel data.

  • Low-level Canvas drawing where you require exact pixels (and you handle density conversion yourself).

  • Hardware-specific assets; otherwise, prefer density-aware drawables or vector drawables.

You’ll also see other units (in, mm, pt). They’re rarely needed for standard Android UI work; dp/sp cover the usual cases.

A note about terms: dip and dp are interchangeable (dp is the modern term). Stack Overflow’s community answers cover this equivalence well if you want a quick community reference (Stack Overflow thread).

Converting android dp to px: formulas and examples

Sometimes you must convert dp/sp to px in code—here’s how.

Math (conceptual):

  • px = dp × (dpi / 160)
  • Android exposes a density scalar: density = dpi / 160, so px = dp × density.

Example numbers:

  • mdpi (160 dpi): density = 1.0 → 16dp = 16px
  • xhdpi (320 dpi): density = 2.0 → 16dp = 32px
  • xxhdpi (480 dpi): density = 3.0 → 16dp = 48px

Kotlin/Java (common approaches):

Kotlin (simple multiplication)

kotlin
fun dpToPx(dp: Float, context: Context): Int {
 val density = context.resources.displayMetrics.density
 return (dp * density + 0.5f).toInt() // rounds to nearest pixel
}

Using TypedValue (Android framework helper)

kotlin
val px = TypedValue.applyDimension(
 TypedValue.COMPLEX_UNIT_DIP, dpValue, resources.displayMetrics
)

For sp to px (text):

kotlin
val px = TypedValue.applyDimension(
 TypedValue.COMPLEX_UNIT_SP, spValue, resources.displayMetrics
)

Jetpack Compose (modern API)

kotlin
with(LocalDensity.current) {
 val px = 16.dp.toPx()
 val textPx = 14.sp.toPx()
}

(Compose LocalDensity docs and usage: Jetpack Compose LocalDensity article.)

If you need a quick web conversion, remember the baseline: 1 dp = 1 px at 160 dpi; multiply by density for other screens (iHeavy conversion explanation, DzungVu conversion post).

Android Studio, Jetpack Compose and testing tips

  • Android Studio layout editor uses dp as the default measurement. When you specify sizes in XML you’ll usually see dp units in the UI preview—so when someone asks “how to set android studio dp?”, that’s where it shows up.
  • In Compose, work with dp and sp values and convert when you need raw pixels using LocalDensity (see previous section). Compose encourages using typed units (Dp/Sp) rather than raw ints, which reduces errors (Compose LocalDensity example).
  • Test across densities: use emulator/device profiles (ldpi, mdpi, hdpi, xhdpi, xxhdpi) and scale the font preference in Settings to verify sp scaling. Android Studio’s device preview and Layout Inspector help here.
  • Don’t confuse unit names with unrelated tools: for instance, “SP Flash Tool” (search term: sp flash tool android) is a firmware utility and has nothing to do with scale-independent pixels—same letters, different domain. Be careful when searching.

Common pitfalls and quick checklist

Common mistakes and how to avoid them:

  • Using px for layout: your UI will break across densities. Avoid.
  • Using sp for icons or non-text UI: if you use sp for non-text elements they’ll resize with font settings and can break layout.
  • Forgetting to round when converting: fractional px values may be truncated; use Math.round or add 0.5f before casting to int.
  • Relying on hard-coded pixel sizes in images: provide multiple density assets or use vector drawables.
  • Mixing units inconsistently: prefer dp for layout and sp for text everywhere—consistency reduces surprises.

Quick QA checklist before release:

  • [ ] Layouts use dp for sizes/margins/padding.
  • [ ] All visible text uses sp.
  • [ ] Images have appropriate density variants or vectors.
  • [ ] Tested on at least mdpi, xhdpi and xxhdpi device/emulators.
  • [ ] Font scaling tested with larger accessibility text size.

If you want deeper reading or community examples, see the comparisons and guides linked below (practical explanations and best-practice tips are collected in community posts and official docs).

Sources

Conclusion

Think of dp as the layout unit and sp as the text unit: android dp keeps your UI physically consistent across densities, android sp adds the user’s font-size preference so text stays readable, and px is the raw pixel you use only when exact pixel control is required. Keep layouts in dp, text in sp, and convert to px programmatically when you must—test on multiple densities and font scales to catch issues early.

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Android PX vs DP vs DIP vs SP: Differences & Usage