From 86222c99e98012c96e1b594524b323e96a3edde8 Mon Sep 17 00:00:00 2001
From: Brandon Liu <bdon@users.noreply.github.com>
Date: Wed, 31 Mar 2021 17:51:00 +0800
Subject: [PATCH] Update README.md

---
 README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/README.md b/README.md
index c49d346..f7db625 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ A detailed specification is forthcoming. PMTiles is a binary serialization forma
 
 ### Design considerations
 * Directories are recursive, with a maximum of 21,845 entries per directory.
+  * *21845 is the total tiles of a pyramid with 7 levels, or 1+4+16+64+256+1024+4096+16384*
 * Deduplication of tile data is handled by multiple entries pointing to the same offset in the archive.
 
 ### Details