Mechanism◆Article
Napkin math — quick calculations to get rough answers — is a powerful way to challenge existing systems and reveal why products run slowly or cost too much.
Simon Eskildsen developed 'napkin math' as a toolkit to calculate theoretical limits of compute operations, enabling him to challenge benchmarks and design decisions by comparing real-world performance against first-principles expectations. ✦ AI generated
Simon Eskildsen · The Pragmatic Engineer · 2026-07-21 · original ↗
Napkin math was essentially just this table that I maintain on GitHub. There's probably like 50 of these numbers and then a script that generates them all. For example, what does a gigabyte of memory cost? $2. What does a gigabyte of S3 cost? Two cents... I had a massive table, then I created flashcards for almost every single cell so I know all these numbers. This was a project I started taking on at Shopify because I would review projects and these numbers would be helpful.
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- ·Quick calculations to reveal why systems are slow or expensive
- ·Challenges benchmarks and design decisions with theoretical limits
- ·1 GB of memory costs ~$2
- ·1 GB of S3 storage costs ~$0.02
- ·Simon maintains a table of ~50 numbers and flashcards
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