KB vs KiB vs MB Explained: Why File Sizes Differ Across Systems
Understand the difference between decimal KB (1,000 bytes) and binary KiB (1,024 bytes). Learn why portal upload limits reject files that appear compliant.
1 KB (kilobyte) in decimal equals 1,000 bytes, while 1 KiB (kibibyte) in binary equals 1,024 bytes. Windows calculates file sizes using binary (1,024) but labels them as 'KB', whereas macOS and online server validators often enforce decimal (1,000) or strict byte ceilings (e.g., exactly 204,800 bytes for a 200 KB cap). This discrepancy is the #1 reason uploads get rejected when users think their file is within the limit.
If an online form enforces a strict 200 KB limit ($200,000$ bytes) and your Windows Explorer shows '198 KB' ($198 \times 1,024 = 202,752$ bytes), the portal validator will reject the file as oversized. Modifyle inspects the exact file.size in bytes to eliminate this discrepancy.
Inspect the true byte weight of your document against portal limits.
Frequently Asked Questions
How can I check the exact byte size of my file on Windows?
How does Modifyle ensure files satisfy portal upload caps?
Blob.size in memory and aims for a safe margin (for example, target 190 KB for a 200 KB cap) to guarantee acceptance regardless of whether the server uses binary or decimal calculation.