ESP32 Flash Address Reference

ReferenceESP Flasher AppUpdated: July 25, 2026

When flashing firmware to an ESP32 or related chip, the flash address determines where each binary is written in the chip's flash memory. Using the wrong address will cause the device to fail to boot. This page documents the correct flash addresses for all supported Espressif chips.

Quick Reference Table

Chip Family	Bootloader	Partition Table	Application (App)	NVS	OTA Data
ESP32 (classic)	0x1000	0x8000	0x10000	0x9000	0xD000
ESP32-S2	0x0	0x8000	0x10000	0x9000	0xD000
ESP32-S3	0x0	0x8000	0x10000	0x9000	0xD000
ESP32-C2	0x0	0x8000	0x10000	0x9000	0xD000
ESP32-C3	0x0	0x8000	0x10000	0x9000	0xD000
ESP32-C6	0x0	0x8000	0x10000	0x9000	0xD000
ESP32-H2	0x0	0x8000	0x10000	0x9000	0xD000
ESP8266	0x0	N/A	0x0	N/A	N/A

Key rule: For any single merged/factory .bin file, always use address 0x0 regardless of chip family. The merge_bin tool packs all partitions at their correct offsets within the file.

Why These Addresses Matter

ESP32 flash is divided into partitions defined by a partition table stored at offset 0x8000. The ROM bootloader reads this table to find the application to boot. If you write firmware to the wrong address:

The bootloader won't find valid firmware and will panic with "invalid header: 0xffffffff"
Multi-file flashing with mismatched addresses overwrites existing partitions
OTA updates will fail because the OTA data partition is corrupted

Flash Address Rules by File Type

File Type	Common Name Pattern	Address
Single merged / factory	factory.bin, merged.bin, firmware.bin	0x0
Bootloader (ESP32)	bootloader.bin	0x1000
Bootloader (C3/S3/C6/H2)	bootloader.bin	0x0
Partition table	partitions.bin	0x8000
Application / App	app.bin, firmware.bin, BlinkTest.ino.bin	0x10000
NVS (WiFi credentials)	nvs.bin	0x9000
OTA data	otadata.bin	0xD000
SPIFFS / LittleFS	spiffs.bin, littlefs.bin	0x290000

How ESP Flasher App Auto-Detects Addresses

When you upload a .bin file to ESP Flasher App, it analyzes the filename and auto-selects the flash address:

bootloader in the name → 0x1000
partition in the name → 0x8000
factory or merged in the name → 0x0
spiffs or littlefs in the name → 0x290000
Otherwise → 0x10000 (app partition)

Warning: You can override the auto-detected address before flashing. If your device fails to boot after flashing, the most likely cause is an incorrect flash address. Double-check against the table above.

Partition Table Structure

The ESP32 partition table (at 0x8000) is a 1024-byte binary structure containing up to 95 partition entries. Each entry is 32 bytes and specifies:

Type — app (0x00) or data (0x01)
Subtype — factory, ota_0, ota_1, nvs, spiffs, etc.
Offset — flash address where the partition starts
Size — partition length in bytes
Label — human-readable name (nvs, otadata, app, etc.)

ESP Flasher App includes a built-in Partition Table Viewer in the Guide tab — upload any partition table .bin to see its entries decoded.

Related Resources

ESP Flasher App — Free browser-based ESP firmware flasher
esptool Guide — How the ESP ROM bootloader protocol works
ESP-IDF Partition Tables Documentation

ESP Flasher App — Browser-based ESP32 & ESP8266 firmware flashing tool