This key facts covers Image File Size Calculation within Images & Sound for GCSE Computer Science. Revise Images & Sound in Memory & Storage for GCSE Computer Science with 18 exam-style questions and 16 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 5 of 11 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 5 of 11
Practice
18 questions
Recall
16 flashcards
Image File Size Calculation
Formula:
File Size (bits) = Width × Height × Color Depth File Size (bytes) = (Width × Height × Color Depth) ÷ 8
Example 1: Simple Calculation
Image: 800 × 600 pixels, 24-bit color depth Step 1: Calculate total pixels 800 × 600 = 480,000 pixels Step 2: Calculate bits 480,000 pixels × 24 bits = 11,520,000 bits Step 3: Convert to bytes 11,520,000 bits ÷ 8 = 1,440,000 bytes Step 4: Convert to MB (optional) 1,440,000 bytes ÷ 1,048,576 = 1.37 MB
Example 2: HD Photo
Image: 1920 × 1080 pixels, 24-bit color depth 1920 × 1080 = 2,073,600 pixels 2,073,600 × 24 = 49,766,400 bits 49,766,400 ÷ 8 = 6,220,800 bytes ≈ 6.2 MB
Example 3: Different Color Depths
Same image (640 × 480 pixels) at different color depths: 1-bit (B&W): 640 × 480 × 1 ÷ 8 = 38,400 bytes (37.5 KB) 8-bit (256 colors): 640 × 480 × 8 ÷ 8 = 307,200 bytes (300 KB) 24-bit (True Color): 640 × 480 × 24 ÷ 8 = 921,600 bytes (900 KB) 24-bit is 24× larger than 1-bit!