Dummy 1 MB CSV File
Generate and download a dummy 1 MB CSV file. The download is exactly 1,048,576 bytes, created in your browser and never uploaded.
Need a different size? Make a dummy CSV file of any size from 7 Bytes to 50 MB.
Testing with a 1 MB CSV file
One megabyte matches the default nginx body limit. A file of exactly 1 MB is rejected by default nginx once multipart overhead is added.
This is a good size for checking batch inserts: set Rows to 10,000 and the file holds that many complete rows, which exposes N+1 query problems that a 5-row file never shows.
With the default 5 rows, each row carries about 200 KB of filler in its last column (1 MB divided by 5). That makes a good test of how a parser handles very long cells and any line-length limit.
- Exact size (binary)
- 1,048,576 bytes
- Decimal equivalent
- 1,000,000 bytes
- Base64-encoded size
- 1,398,104 bytes
- Rows and columns
- 5 rows x 10 columns by default (choose 1 to 1,000,000 rows and 1 to 100 columns in Options)
- Most rows at 10 columns
- 10,247
Exact size and boundary files for 1 MB
Set the unit to B and enter these byte counts to test either reading of 1 MB.
| Limit defined as | One under (should pass) | At the limit | One over (should fail) |
|---|---|---|---|
| Binary 1 MB | One under (should pass) 1,048,575 B | At the limit 1,048,576 B | One over (should fail) 1,048,577 B |
| Decimal 1 MB | One under (should pass) 999,999 B | At the limit 1,000,000 B | One over (should fail) 1,000,001 B |
Limits closest to 1 MB
A 1 MB file is exactly at nginx (1 MB); under PHP (2 MB), AWS Lambda (6 MB), API Gateway (10 MB), Outlook with Exchange (10 MB), Outlook with internet accounts (20 MB), Gmail (25 MB) and Cloudflare Free and Pro (100 MB). Sent as base64 text it grows past nginx.
| Limit | Size | Notes |
|---|---|---|
| nginx client_max_body_size (default) | 1 MB 1,048,576 B | Requests with a larger body get HTTP 413. |
| PHP upload_max_filesize (default) | 2 MB 2,097,152 B | Also capped by post_max_size, so raise both. |
Other dummy CSV file sizes
Smaller: 100 KB CSV. Larger: 10 MB CSV. Or see the full dummy CSV file generator.
Other 1 MB dummy files
The same size in another file type.
1 MB CSV file FAQ
Is the 1 MB CSV file exactly 1 MB?
Yes: 1,048,576 bytes in binary units. For a decimal 1 MB, set the unit to B and enter 1,000,000.
How many rows are in a 1 MB dummy CSV?
5 data rows plus the header by default, because you choose the rows in Options and the size does not change the count. At 10 columns a 1 MB file can hold up to 10,247 rows, and the Number of rows option stops at 1,000,000. The file stays exactly 1,048,576 bytes, with the extra bytes as filler in the last column.
Will a 1 MB dummy CSV open in Excel without losing rows?
Yes, as far as the row limit goes. The file has the rows you choose, at most 1,000,000 plus the header, which is under Excel's 1,048,576-row worksheet limit, so no rows fall past it. No row is cut to reach 1,048,576 bytes.
Will a 1 MB CSV file pass the nginx client_max_body_size (default)?
Probably not. At exactly 1,048,576 bytes it equals the 1 MB limit in binary units, and a form upload adds a few hundred bytes of multipart boundary and headers, so the body ends up over. Counted in decimal megabytes (1,000,000 bytes) the file is 48,576 bytes over. Test one byte under to see it pass. As base64 it is 1,398,104 characters, over the limit, and that is the size that counts in a JSON body or an email.
Is the file uploaded anywhere?
No. It is generated in your browser and never leaves your device.