CODEWITHSUNDEEP
javascriptcanvasbase64
daisy
daisy

Reputation: 675

What is a base64 length in bytes?

I have a file encoded in Base64 with a certain file length. How do I get the size in bytes?

Example:

var size= canvas.toDataURL();   

console.log(resizeCanvasURL.length);


// -> 132787  base64 length

Upvotes: 7

Views: 19307

Answers (3)

Peter Mounir
Peter Mounir

Reputation: 41

const stringLength = resizeCanvasURL.length 
const sizeInBytes = 4 * Math.ceil(stringLength / 3) * 0.5624896334383812;
const sizeInKb = sizeInBytes / 1000;

OR

 const stringLength = resizeCanvasURL.length 
 const sizeInBytes = stringLength * (3 / 4) - 2;
 const sizeInKb = sizeInBytesNew / 1000;

Upvotes: 0

Vincent Hoch-Drei
Vincent Hoch-Drei

Reputation: 661

The answer from mishik is wrong.

Base64 is filled up with =-chars (to have the right amount of bits). So it should be

    var byteLength = parseInt((str).replace(/=/g,"").length * 0.75));

Upvotes: 8

mishik
mishik

Reputation: 10003

Each symbol in Base64 encoding holds 6 bits of information. Each symbol in normal file hold 8 bits. Since after decoding you have the same amount of information you need:

normal file size - 1000 bytes
base64 file size - 1333 bytes

Upvotes: 10

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