🖼️ How Much Space Do Photos and Songs Take? — Storage Calculator

Calculate how much storage bitmap images and sound files need — with full working shown step by step.

Designed with the WJEC specification in mind

CS GCSE §1.2.1DigiTech GCSE §1.1.2

🤔 What determines file sizes?

Digital photos and music files are made of data. Higher quality means bigger files! Image size depends on resolution and colour depth. Sound size depends on sample rate, bit depth, and duration.

🍕 Analogy: It's like a digital recipe — more ingredients (pixels, color info, sound samples) = bigger meal (file size)!

🖼️ Bitmap Image

🔊 Sound File

🎬 Video File

📏 Units Explained

📊 Compare

🖼️

Bitmap Image File Size

Presets:

Width (pixels)

Height (pixels)

Colour depth (bits)

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Key Concepts

Resolution = width × height (total number of pixels)

Colour depth = number of bits per pixel. More bits = more colours but bigger file.

Formula: File size = width × height × colour depth

This gives the uncompressed file size. Real images (JPEG, PNG) use compression to reduce this.

🔊

Sound File Size

Presets:

Sample rate (Hz)

Bit depth

Channels

Duration (seconds)

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Key Concepts

Sample rate = how many times per second the sound wave is measured (Hz).

Bit depth = how many bits are used to store each sample. More bits = more detail.

Channels = mono (1) or stereo (2). Stereo doubles the file size.

Formula: File size = sample rate × bit depth × channels × duration

🎬

Video File Size

Presets:

Width (px)

Height (px)

Colour depth (bits)

Frame rate (FPS)

Duration (seconds)

Audio track:

Sample rate

Bit depth

Channels

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Key Concepts

FPS (Frames Per Second) = how many still images are shown each second. Higher FPS = smoother motion but bigger files.

Video formula: File size = (width × height × colour depth × FPS × duration) + audio size

A video is just a sequence of bitmap images played quickly, plus an audio track. That's why uncompressed video is enormous — a 2-minute 1080p clip is about 22 GB uncompressed!

Real video files (MP4, MKV) use lossy compression to shrink this by 100-1000×. That's why compression is so important.

📏

Data Size Units

Unit	Size	Real-world example
1 Bit	0 or 1	A single yes/no answer
1 Byte (B)	8 bits	One character (letter, number, symbol)
1 Kilobyte (KB)	1,024 bytes	A short text message or email
1 Megabyte (MB)	1,024 KB	A photo from your phone, or a 1-minute MP3
1 Gigabyte (GB)	1,024 MB	About 250 songs, or a 1-hour Netflix show (compressed)
1 Terabyte (TB)	1,024 GB	About 500 hours of HD video, or a laptop hard drive
1 Petabyte (PB)	1,024 TB	All the photos on Facebook, or Netflix's entire library
1 Exabyte (EB)	1,024 PB	All the data on the internet is roughly 5 exabytes

💡 Why 1,024 and not 1,000?
Computers work in binary (base 2), so 1 KB = 2¹⁰ = 1,024 bytes, not 1,000. This is because 1,024 is the closest power of 2 to 1,000. Some manufacturers use 1,000 instead (which is why your "500 GB" hard drive shows as ~465 GB on your computer!).

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Quick Comparison

See how different settings affect file size. Click a scenario to see the working.

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Exam Tips

GCSE: Remember the formula: width × height × colour depth (in bits) = file size in bits
Key point: Convert between bits, bytes, KB, MB correctly (8 bits = 1 byte, 1024 bytes = 1 KB)
Sound: Sample rate × bit depth × duration × channels = file size
Remember: Higher quality = larger files but better image/sound quality