Ninjabrain Bot
A stronghold calculator for Minecraft speedrunning. Throw an eye of ender, look at it and press F3+C, and Ninjabrain Bot ranks the likely stronghold locations with a probability for each one.
Purpose
Turns your eye of ender throws into stronghold coordinates, so you don't have to work out the triangulation yourself.
Setup Guide
Download the latest .jar from the GitHub releases page. In September 2026 that was version 1.5.2, released on March 24.
Open the .jar. You need Java installed for that, and because the project is built for Java 8, any newer Java works too.
In the game, throw an eye of ender, stand completely still, look straight at the eye and press F3+C.
Walk to a new spot and throw again. Every throw updates the list of candidate strongholds and their probabilities.
Missed the stronghold even though the certainty was high? You probably moved during a throw. Wait a moment after stopping, or push yourself into a corner between two blocks before you throw.
Run Calibrate standard deviation in the advanced settings once. That value tells the calculator how accurate your measurements are, and a value that is too low makes the certainty overconfident.
Turn on Show direction to stronghold, then press F3+C while looking down to get the angle and distance from where you stand. In the Nether you don't have to look down.
Features
- +Stronghold predictions from any number of eye throws
- +A probability for every candidate location, based on your measurement error and on how strongholds generate
- +Standard deviation calibration and subpixel angle adjustment
- +Direction and distance updates while you travel
- +Blind coordinates from the Nether and fossil divine calculations
- +High precision boat measurements
- +An All Advancements mode for Minecraft 1.20 and later
- +An OBS overlay that hides when there is no result, and an HTTP API for other tools
How Ninjabrain Bot calculates a stronghold
Plain triangulation draws a line through two eye throws and takes the point where the lines cross. That only works if both angles are exact, and nobody aims at an eye of ender perfectly, least of all when the stronghold is far away.
Ninjabrain Bot treats every angle as a measurement with some noise in it. It models your aiming error as a normal distribution, sized by the standard deviation in the settings, and after each throw it uses Bayes' theorem to update the probability of every candidate stronghold chunk. Before the first throw it already knows that strongholds generate in rings, that their positions snap to chunks and biomes, and that an eye points to the nearest stronghold.
The certainty on screen is the probability that comes out of that model, so it can only be as good as what goes in. A throw made while you were still moving, or a standard deviation lower than your real error, makes it too confident. The README links the full derivation, a paper called Predicting stronghold locations with Bayesian statistics.
Settings worth knowing
Most of what decides how accurate the calculator is for you sits in the settings, and a few of the options are easy to misread.
- Display stronghold location using: (4, 4) gives the coordinates of the starter staircase, (8, 8) the (8, 8) position in the stronghold chunk and Chunk the chunk coordinates. It changes how the result is shown, not how it is calculated.
- Crosshair correction: leave it at 0 unless your setup is one of the known cases. For 1440p fullscreen the README gives 0.026 with GUI scale 3 and 0.104 with GUI scale 6 or Auto.
- Subpixel adjustment: bind hotkeys to +0.01 to last angle and -0.01 to last angle to nudge your latest F3+C measurement. At a resolution of 1920x1027, an eye with a wide middle slit may need a press of +0.01.
- Show angle errors: shows how far each throw is from the angle to the predicted stronghold. Unusually large errors may mean an eye was measured wrong or thrown while you were moving, and a separate option warns you when the calculator detects that.
- Use advanced stronghold statistics: takes the other strongholds and the nearest stronghold rule into account. The README says to leave it on for almost everyone.
- Direction help: an info message that tells you how many blocks to move sideways so your next throw gets you to about 95% certainty.
Boats, the Nether and All Advancements
Boat measurements give a far more precise angle than aiming by hand. Once you turn on Enable boat measurements, the settings offer a default boat mode (gray, blue or green boat) and a separate standard deviation for boat throws, and the project wiki has a page on the method.
Blind coordinates don't need an eye at all: press F3+C in the Nether where you plan to build a portal, and the calculator evaluates that spot for blind travel.
All Advancements mode saves structure coordinates after the Any% part of a run. Press F3+C at spawn, standing on the ground with x and z under 300, for the spawn and shulker entry, underwater below y 63 for an ocean monument, and while looking at the center of an outpost to have its position estimated. The mode switches on when you enter the End, on Windows and macOS only, or with a hotkey, and there is a separate mode for 1.20 and later.
For streams, the OBS overlay is an image that looks exactly like the Ninjabrain Bot window and hides itself when nothing is shown. Add it in OBS as an image source.
Notes
Stronghold calculators have been allowed in Minecraft speedruns since December 9, 2021, and speedrun.com lists Ninjabrain Bot as a resource for the game. It still pays to read the category rules before you submit a run. The project started in November 2020 as a Twitch chat bot and is now a desktop app, released under the GPL 3.0 license.
Questions about Ninjabrain Bot
What standard deviation should I use in Ninjabrain Bot?
The value that Calibrate standard deviation gives you, since accuracy depends on your FOV, resolution, mouse sensitivity and experience. As a rough guide the README lists 0.050 to 0.200 when measuring in Quake Pro, 0.020 to 0.040 at 30 FOV and 0.005 to 0.010 at 30 FOV with subpixel adjustment. A value lower than your real error makes the certainty too high.
What does the Lock calculator hotkey do?
It toggles locked mode. While locked, the reset, undo and subpixel hotkeys do nothing, Auto reset when idle for 15 minutes won't clear the calculator, and F3+C updates the direction and distance from where you stand instead of adding another throw.
Does Ninjabrain Bot work on Minecraft 1.9 to 1.12?
Yes. Next to the standard deviation and calibration for 1.13 and later, the settings have a separate standard deviation and calibration for 1.9 to 1.12.