S3 Storage Cost Calculator: Avro (Snappy) vs JSON (Gzip)

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Updated: June 2025

Calculation Assumptions

Message Structure: JSON messages on Kafka with thousands of fields (e.g., {"field1": 123, "field2": "Alice", ...}). Avro uses AvroFormat with Schema Registry (4-byte schema ID). JSON uses JsonFormat with Gzip.
JSON-to-Avro Conversion Ratio: Adjustable (default 0.4), reflecting Avro's reduction of JSON size before compression due to high field count.
Compression Ratios: JSON (Gzip) achieves 4x compression (e.g., 5KB → 1.25KB). Avro (Snappy) achieves 3x compression on binary data (e.g., 2KB → 0.67KB).
File Overhead: Avro: 4-byte schema ID + 100-byte header per file (0.104 bytes/message at flush.size=1000). JSON: 20-byte Gzip metadata per file (0.02 bytes/message).
S3 Storage Cost: $0.023/GB/month (us-east-1, June 2025). Daily cost: (GB × $0.023 / 30). Yearly cost: (GB × $0.023 × 12).
Kafka Connect: flush.size=1000, hourly files (rotate.schedule.interval.ms=3600000).
Message Volumes: 1M, 10M, or 100M messages/day. Monthly = 30 days, Yearly = 365 days.

💡 Tip: Adjust the JSON-to-Avro ratio based on your actual data (test with aws s3 ls --summarize) to refine results.

Input Parameters

Message Size (KB)

Messages per Day

JSON-to-Avro Conversion Ratio

0.40

Lower values indicate more efficient Avro compression

💰 Cost and Storage Breakdown

Metric	Raw JSON	Avro (Snappy)	JSON (Gzip)	Savings (Avro vs JSON)

Legend: ✓ Green values indicate Avro savings. ✗ Red values indicate JSON is more efficient.

📊 Is Avro Worth It?

Avro (Snappy) is highly valuable for schemas with thousands of fields, especially with the adjustable JSON-to-Avro ratio. A lower ratio (0.3–0.4) can yield significant storage savings (up to 50%+), which becomes critical for high volumes (10M+/day). Avro's schema evolution via Schema Registry also simplifies managing complex, evolving schemas, outperforming JSON (Gzip)'s lack of schema support. Test your actual data to optimize the ratio and confirm savings.

About This Calculator

This AWS S3 storage cost calculator helps you compare the storage efficiency and costs between Avro with Snappy compression and JSON with Gzip compression for your Kafka data streaming pipelines.

Whether you're processing millions of messages per day or optimizing cloud storage costs, this tool provides accurate estimates based on real-world compression ratios and AWS S3 pricing.

Perfect for: Data engineers, DevOps teams, cloud architects, and anyone working with high-volume data streams who wants to optimize their AWS storage costs.

⚠️ Important Disclaimer

Educational Purpose Only: This calculator is provided for informational and educational purposes only. Results are estimates based on theoretical models and assumptions.

No Financial Advice: This tool does not constitute financial, technical, or professional advice. Always consult with qualified professionals for business decisions.

Accuracy Not Guaranteed: While we strive for accuracy, compression ratios, storage costs, and actual results may vary significantly based on your specific data, AWS region, pricing changes, and implementation details.

Your Responsibility: Users are solely responsible for validating calculations, testing with their actual data, and making informed decisions. Always verify costs through official AWS pricing calculators and your own testing.

No Liability: We disclaim all liability for any losses, damages, or costs incurred from using this calculator or acting on its results. Use at your own risk.

Recommendation: Test with your actual data and workloads before making production decisions. AWS pricing and compression results can vary significantly from these estimates.