Check size of uploaded file in mb

Question

I need to verify that a file upload by a user does not exceed 10mb. Will this get the job done?

var fileSize = imageFile.ContentLength;
if ((fileSize * 131072) > 10)
{
    // image is too large
}

I've been looking at this thread, and this one... but neither gets me all the way there. I'm using this as the conversion ratio.

.ContentLength gets the size in bytes. Then I need to convert it to mb.

seriously? Why the down votes? You could at least say why. – Casey Crookston Apr 25 '17 at 17:38 — Casey Crookston, Apr 25 '17 at 17:38

DavidG · Accepted Answer · 2017-04-25T17:37:41.993

31

Since you are given the size in bytes, you need to divide by 1048576 (i.e. 1024 * 1024):

var fileSize = imageFile.ContentLength;
if ((fileSize / 1048576.0) > 10)
{
    // image is too large
}

But the calculation is a bit easier to read if you pre-calculate the number of bytes in 10mb:

private const int TenMegaBytes = 10 * 1024 * 1024;


var fileSize = imageFile.ContentLength;
if ((fileSize > TenMegaBytes)
{
    // image is too large
}

edited Apr 25 '17 at 17:37

answered Apr 25 '17 at 17:27

DavidG

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But why 131072? – Evk Apr 25 '17 at 17:30
First examp!e is wrong still, because you perform integer division. So if file is 10.5mb - it will not get into image is too large branch. – Evk Apr 25 '17 at 17:37

score 3 · Answer 2 · answered Apr 25 '17 at 17:27

3

You can use this method to convert the bytes you got to MB:

static double ConvertBytesToMegabytes(long bytes)
{
    return (bytes / 1024f) / 1024f;
}

answered Apr 25 '17 at 17:27

Koby Douek

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19
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Was going to ask why this is a double, but that's a good call! – VSO Sep 21 '20 at 14:22

score 2 · Answer 3 · edited Nov 27 '19 at 07:40

2

Prefixes for multiples of bytes (B):
1024 bytes = 1kilobyte
1024 kilobyte = 1megabyte

double ConvertBytesToMegabytes(long bytes)
{
    return (bytes / 1024f) / 1024f;
} 

var fileSize = imageFile.ContentLength;

if (ConvertBytesToMegabytes(fileSize ) > 10f)
{
    // image is too large
}

edited Nov 27 '19 at 07:40

Yousha Aleayoub

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answered Apr 25 '17 at 17:31

oziomajnr

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score 2 · Answer 4 · answered Apr 25 '17 at 17:31

2

var fileSize = file.ContentLength;
if (fileSize > 10 * 1024 * 1024)
{
    // Do whatever..
}

answered Apr 25 '17 at 17:31

loneshark99

706
5
16

Check size of uploaded file in mb

4 Answers4