diff --git a/app/src/main/java/org/koitharu/kotatsu/domain/MangaPreferencesRepository.kt b/app/src/main/java/org/koitharu/kotatsu/domain/MangaPreferencesRepository.kt
index fdf14f74a..72c261080 100644
--- a/app/src/main/java/org/koitharu/kotatsu/domain/MangaPreferencesRepository.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/domain/MangaPreferencesRepository.kt
@@ -19,8 +19,7 @@ class MangaPreferencesRepository : KoinComponent {
 		)
 	}
 
-	suspend fun getReaderMode(mangaId: Long): ReaderMode {
+	suspend fun getReaderMode(mangaId: Long): ReaderMode? {
 		return db.preferencesDao().find(mangaId)?.let { ReaderMode.valueOf(it.mode) }
-			?: ReaderMode.UNKNOWN
 	}
 }
\ No newline at end of file
diff --git a/app/src/main/java/org/koitharu/kotatsu/domain/MangaUtils.kt b/app/src/main/java/org/koitharu/kotatsu/domain/MangaUtils.kt
new file mode 100644
index 000000000..7a79c011a
--- /dev/null
+++ b/app/src/main/java/org/koitharu/kotatsu/domain/MangaUtils.kt
@@ -0,0 +1,57 @@
+package org.koitharu.kotatsu.domain
+
+import android.graphics.BitmapFactory
+import android.util.Size
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import org.koin.core.KoinComponent
+import org.koin.core.get
+import org.koitharu.kotatsu.BuildConfig
+import org.koitharu.kotatsu.core.model.MangaPage
+import org.koitharu.kotatsu.core.prefs.ReaderMode
+import org.koitharu.kotatsu.utils.ext.await
+import org.koitharu.kotatsu.utils.ext.medianOrNull
+import java.io.InputStream
+
+object MangaUtils : KoinComponent {
+
+	/**
+	 * Automatic determine type of manga by page size
+	 * @return ReaderMode.WEBTOON if page is wide
+	 */
+	suspend fun determineReaderMode(pages: List<MangaPage>): ReaderMode? {
+		try {
+			val page = pages.medianOrNull() ?: return null
+			val url = MangaProviderFactory.create(page.source).getPageFullUrl(page)
+			val client = get<OkHttpClient>()
+			val request = Request.Builder()
+				.url(url)
+				.get()
+				.build()
+			val size = client.newCall(request).await().use {
+				getBitmapSize(it.body?.byteStream())
+			}
+			return when {
+				size.width * 2 < size.height -> ReaderMode.WEBTOON
+				else -> ReaderMode.STANDARD
+			}
+		} catch (e: Exception) {
+			if (BuildConfig.DEBUG) {
+				e.printStackTrace()
+			}
+			return null
+		}
+	}
+
+	@JvmStatic
+	private fun getBitmapSize(input: InputStream?): Size {
+		val options = BitmapFactory.Options().apply {
+			inJustDecodeBounds = true
+		}
+		BitmapFactory.decodeStream(input, null, options)
+		val imageHeight: Int = options.outHeight
+		val imageWidth: Int = options.outWidth
+		check(imageHeight > 0 && imageWidth > 0)
+		return Size(imageWidth, imageHeight)
+	}
+}
\ No newline at end of file
diff --git a/app/src/main/java/org/koitharu/kotatsu/ui/reader/ReaderPresenter.kt b/app/src/main/java/org/koitharu/kotatsu/ui/reader/ReaderPresenter.kt
index f33e981f0..71922a66f 100644
--- a/app/src/main/java/org/koitharu/kotatsu/ui/reader/ReaderPresenter.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/ui/reader/ReaderPresenter.kt
@@ -15,6 +15,7 @@ import org.koitharu.kotatsu.core.model.MangaPage
 import org.koitharu.kotatsu.core.prefs.ReaderMode
 import org.koitharu.kotatsu.domain.MangaPreferencesRepository
 import org.koitharu.kotatsu.domain.MangaProviderFactory
+import org.koitharu.kotatsu.domain.MangaUtils
 import org.koitharu.kotatsu.domain.history.HistoryRepository
 import org.koitharu.kotatsu.ui.common.BasePresenter
 import org.koitharu.kotatsu.utils.MediaStoreCompat
@@ -34,7 +35,18 @@ class ReaderPresenter : BasePresenter<ReaderView>() {
 					val chapter = state.chapter ?: repo.getDetails(state.manga).chapters
 						?.first { it.id == state.chapterId }
 					?: throw RuntimeException("Chapter ${state.chapterId} not found")
-					repo.getPages(chapter) to MangaPreferencesRepository().getReaderMode(state.manga.id)
+					var mode = MangaPreferencesRepository().getReaderMode(state.manga.id)
+					val pages = repo.getPages(chapter)
+					if (mode == null) {
+						mode = MangaUtils.determineReaderMode(pages)
+						if (mode != null) {
+							MangaPreferencesRepository().saveData(
+								mangaId = state.manga.id,
+								mode = mode
+							)
+						}
+					}
+					pages to (mode ?: ReaderMode.UNKNOWN)
 				}
 				viewState.onInitReader(pages, mode, state)
 			} catch (e: Exception) {
diff --git a/app/src/main/java/org/koitharu/kotatsu/utils/ext/CollectionExt.kt b/app/src/main/java/org/koitharu/kotatsu/utils/ext/CollectionExt.kt
index d52571cf1..525aee647 100644
--- a/app/src/main/java/org/koitharu/kotatsu/utils/ext/CollectionExt.kt
+++ b/app/src/main/java/org/koitharu/kotatsu/utils/ext/CollectionExt.kt
@@ -19,4 +19,9 @@ inline fun <T> Iterable<T>.sumByLong(selector: (T) -> Long): Long {
 		sum += selector(element)
 	}
 	return sum
+}
+
+fun <T> List<T>.medianOrNull(): T? = when {
+	isEmpty() -> null
+	else -> get((size / 2).coerceIn(indices))
 }
\ No newline at end of file