A private FIRE calculator suite that runs in the browser

Details

External ID

46846559

Source

HN

Company

—

Product

A private FIRE calculator suite that runs in the browser

Website domain

firenum.com

Launched

Feb. 1, 2026

Cohort

—

Upvotes

5

Upvotes percentile

0.10512129380053908

Tags

—

Fetched at

Sept. 7, 2026, 9:26 p.m.

Updated at

Sept. 7, 2026, 9:26 p.m.

Description

Hi HN,I built Firenum because most FIRE calculators I found were either too simplistic or required uploading my entire financial life to a third-party server.I wanted a comprehensive suite that could model more than just the 4% rule. This tool handles Coast, Lean, Fat, and Barista FIRE, but more importantly, it lets you model 'what-if' scenarios like market crashes or major life events to see how they impact your timeline.Key features:-> Privacy-First: No signup required. All calculations and data persistence happen in your local storage. Nothing is sent to a backend.-> Scenario Modeling: You can simulate market downturns to see the resilience of your plan.-> Multi-Currency: Supports 8 major currencies.-> Progress Tracking: A dashboard to visualize the 'boring middle' of the journey.The goal was to make something as powerful as a complex spreadsheet but with a much better UX. I’d love to hear your thoughts on the projection logic and if there are any specific variables (like tax drag or inflation adjustments) you think are missing.URL: https://firenum.com/I’m happy to answer any questions about the math or the local-first implementation!

• Source listing
• Website