EDC Tools
Free EDC tools: two calculators and a reference map for everyday carry. No EDC tool on this page asks for an email before it answers, none of them carries a number we cannot point at a source for, and all of them work on a phone.
The EDC tools on this site
Two calculators and one reference map, listed below with what each one answers and where its numbers come from. Both calculators work in your browser, keep nothing, and show the arithmetic so you can check it.
| Tool | The question it answers | Where the numbers come from |
|---|---|---|
| Knife steel comparison chart | Which of these steels should I buy, and what am I giving up | Published CATRA and Charpy testing, plus maker datasheets |
| Flashlight runtime calculator | How long will this light actually run, and what does the cold cost me | Battery maker discharge and temperature curves, LED datasheets |
| Carry permit reciprocity map | Where is my permit honored when I drive out of state | State statutes and attorney general reciprocity listings |
EDC tools that calculate
Knife steel comparison chart
Put two to four steels side by side on edge retention, toughness, corrosion resistance, sharpening ease and price, with the published chemistry underneath. Twenty-five steels, and the whole reference table is on the page in plain text so you can quote it.
Flashlight runtime calculator
Pick your cell and how many of them, give it your output in lumens or your measured current draw, and it tells you how long the light will run — including what the cold does to it. Seventeen cells, every capacity figure read off the battery maker’s own discharge curve.
EDC tools you look things up in
Knife laws by state
A map of all fifty states and the District of Columbia colored by whether an automatic knife is legal to own, with a searchable table underneath and its own page for sixteen states so far. New York City and Chicago get their own pages because those states have no preemption, so the city writes its own rule.
Carry permit reciprocity map
Where your permit is honored, where it is not, and the states that will get you in trouble for assuming. Built for people who drive across state lines with a carry gun in the car.
The EDC tools we have not built, and why
A knife law checker — pick a state, a blade length and a carry style, get a verdict — is the tool readers ask for most, and we still have not built one. A legal tool that goes stale is worse than no tool at all, because someone acts on it. What we have built instead is the state-by-state reference above, on a written commitment to recheck every statute every two months. When that review has a few cycles behind it, the checker follows.
How these EDC tools are built
Three rules. Every number traces to a manufacturer datasheet, a published test or a standards document, and anything we cannot source comes out. Anything we work out ourselves rather than measure is labeled as ours, with the arithmetic shown. And the answer appears before we ever mention an email address.
There is a fourth rule that is less obvious. Every table on these pages is real text in the page, not something drawn by a script after the fact. That matters because the machines now answering questions on your behalf do not run scripts, so a tool whose numbers only exist once JavaScript has run is invisible to them. It also means you can select a row, copy it, and paste it somewhere useful.
We would rather ship two EDC tools we can defend line by line than ten that look busy. If you find a number on any of them you think is wrong, say so and bring the source; we will either fix it or show you where ours came from.
How to use these EDC tools without fooling yourself
A comparison is only as honest as the question you bring to it. Three habits keep you out of trouble.
Compare on the row that matches your job, not on the total. The knife steel chart will happily tell you that one steel scores higher across four columns added together, and that sum is close to meaningless. If your knife lives in a pocket and gets rained on, the corrosion row decides it. If you baton wood with a fixed blade, toughness decides it and nothing else comes close. A steel that wins on points can lose badly at the one thing you actually do.
Check the conditions attached to every laboratory figure. Both calculators print the conditions next to the number, and they are not decoration. A steel tested at 62 Rockwell is a different material from the same steel at 58. A cell rated at a gentle trickle is a different cell at a full amp. Any comparison that strips those conditions out to make a tidier table has thrown away the part that decides the answer.
Treat a generous input as a ceiling. The runtime calculator will convert lumens to watts for you, and that conversion has to assume how efficient your light is. It says so on the page, and it says which direction the error runs. When a tool tells you where it is guessing, believe it, and give yourself margin on anything that matters in the dark.
None of that is complicated. It is just the difference between reading a number and understanding one, and it is why every figure on these pages carries its source and its conditions instead of arriving on its own.
How often these are checked
Each tool carries a dated line saying when its data was last checked against the source, and that date is not decoration. The knife steel figures move when a metallurgist publishes new testing, which happens perhaps twice a year. Battery datasheets move when a maker revises a cell, which is rarer still. Carry reciprocity moves constantly, which is why that one is a reference page with a warning on it rather than a tool that hands you a verdict.
When a number changes we correct the page in place and move the date, rather than publishing a new page with the year in the address. A tool that has been right for two years should keep the links and the trust it has earned.
Using these EDC tools on your own site
Both calculators carry an embed button under the results. It gives you an iframe and an attribution line, and the attribution sits in your page rather than inside the frame, so it is visible to a reader and to a search engine. Use them. The reference tables are free to quote with a link back, and the knife steel data is published as a plain data file if you would rather work with the numbers directly.
If you are building something similar, the thing worth copying is not the layout. It is that every table is real text in the page and every figure names its source. That is the part that makes a tool worth linking to.
Data updated September 2026.