Military grid coordinate converter in a single HTML file

Name: Military grid coordinate converter in a single HTML file
Availability: InStock
Author: redgridtactical

by redgridtactical·Mar 25, 2026·3 points·0 comments

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AI Analysis

●MidNiche GemCozy

DMA TM 8358.1 compliant with truncation, but coordinate converters are a solved category.

Strengths

•Client-side only with zero tracking and works offline after first load.
•DMA TM 8358.1 truncation instead of rounding fixes errors in popular npm mgrs package.
•Batch conversion mode handles lists of coordinates instead of one-at-a-time.

Weaknesses

•Single-page utility with no depth beyond what Google Earth or QGIS already provides.
•Free ad-free converter is nice but doesn't differentiate from existing tools.

Post Description

Came across a few online MGRS, lat/lon, UTM, and DMS converters while doing some research for my app. They were covered in ads and none of them supported batch conversions or bearing calculations. I put one together as a single self-contained HTML file.

It auto-detects whatever format you paste in and converts to everything else simultaneously. Also has a bearing/distance calculator, dead reckoning, and batch mode for converting lists. Includes FixPhrase (the open-source, patent-free What3Words alternative) that turns any coordinate into a 4-word phrase.

The engine uses DMA TM 8358.1 (truncation, not rounding. The popular npm mgrs package gets this wrong). Everything runs client-side, no tracking, works offline after first load. ~88KB total. Link is to the repo if anyone wants to poke around.