I benchmarked CSV vs JSON on 200k rows so you don't have to

Benjamin — Thu, 06 Aug 2026 12:01:48 +0000

Most "CSV vs JSON" comparisons are vibes. Here are real numbers, measured on a real dataset.

Setup: 200,000 rows x 12 columns, Node v22.18.0, no streaming tricks.

Metric	Result
CSV file size	20.5 MB
JSON file size	49.3 MB
Size ratio	CSV is 2.4x smaller
CSV to JSON speed	~75,234 rows/sec
JSON to CSV speed	~70,908 rows/sec
Round-trip	Lossless

Why JSON is bigger: repeated key names on every object, plus escaping of quotes and non-ASCII characters. For log files and export pipelines the size gap translates directly into bandwidth and storage costs.

What to use: JSON for APIs and nested structures; CSV for storage, spreadsheets and analytics imports. If your data is a flat table, CSV wins on size and tooling.

I built a free in-browser converter that does JSON↔CSV↔TSV plus a bunch of text utilities, 100% client-side (your data never leaves the machine): https://instant-data-converter.vercel.app

Full guide with methodology: https://instant-data-converter.vercel.app/guides/csv-vs-json

DEV Community: Benjamin

I benchmarked CSV vs JSON on 200k rows so you don't have to