Rocket Calculator ONI: How It Works in Oxygen Not Included

The “Rocket Calculator ONI” refers to community-made tools that compute the fuel, oxidizer, and range requirements for rockets in the game Oxygen Not Included. You enter your rocket’s module configuration and destination, and it returns the exact fuel and oxidizer needed, plus the maximum range. This article explains the underlying mechanics, how to use such a calculator, and common pitfalls.

Formula

The core formula used by most ONI rocket calculators is:

Range = (Fuel × Fuel Efficiency + Oxidizer × Oxidizer Efficiency) × Engine Multiplier

Where:

• Fuel (kg) – the mass of propellant loaded into the rocket.
• Oxidizer (kg) – the mass of oxidizer loaded.
• Fuel Efficiency – distance per kg of fuel (varies by engine type).
• Oxidizer Efficiency – distance per kg of oxidizer (varies by engine type).
• Engine Multiplier – a factor that scales with engine tier (e.g., 1 for Steam, 2 for Petroleum, 3 for Hydrogen).

In the example above, we used simplified efficiencies of 10 tiles/kg for fuel and 5 tiles/kg for oxidizer, with the engine multiplier. Real calculators use the exact values from the game’s code, which are typically 10 and 5 for steam, 20 and 10 for petroleum, and 30 and 15 for hydrogen.

Background: Why Rocket Calculators Exist

Oxygen Not Included (ONI) is a space-colony simulation game where rockets are used to explore asteroids and gather rare resources. The rocket system is complex because each module (engine, fuel tank, oxidizer tank, nose cone, cargo bays) affects mass and range. Players often miscalculate fuel requirements, leading to rockets that run out of fuel mid-flight or waste resources. Rocket calculators solve this by automating the math, letting players plan missions without trial and error.

Community tools appeared soon after the rocketry update in 2019, as players shared spreadsheets and web apps. They are not official, but they are widely used because the in-game UI only shows a rough range estimate, not precise numbers.

How the Rocket System Works

In ONI, a rocket consists of an engine at the bottom, followed by fuel and oxidizer tanks, and then a nose cone and optional cargo modules. The engine determines the thrust and efficiency. Fuel types include steam (for the early Steam Engine), petroleum (for the Petroleum Engine), and liquid hydrogen (for the Hydrogen Engine). Oxidizer is typically oxygen or liquid oxygen, with liquid oxygen being more efficient.

Each tank has a capacity, and the total mass of the rocket affects acceleration and fuel consumption. The game calculates range based on the amount of fuel and oxidizer burned, not just the distance. A calculator helps by converting the desired distance into the required fuel and oxidizer masses, accounting for the engine’s efficiency.

How to Use a Rocket Calculator

Using a typical ONI rocket calculator involves these steps:

1. Select your engine – choose from Steam, Petroleum, or Hydrogen.
2. Enter your module setup – number of fuel tanks, oxidizer tanks, cargo bays, and nose cone type.
3. Enter the destination distance – in tiles (the in-game map shows distances between asteroids).
4. Read the output – the calculator gives the required fuel and oxidizer in kg, and often the maximum range for your current loadout.

Many calculators also let you input the amount of fuel and oxidizer you have, and they output the maximum range you can travel. This is useful for checking if a mission is feasible with your current resources.

Common Mistakes and Misconceptions

One common mistake is confusing oxidizer with fuel. Both are needed, but they have different efficiencies. Another is using the wrong engine multiplier – the Steam Engine is much less efficient than the Hydrogen Engine, so a rocket that works early may not reach far asteroids later.

A frequent misconception is that adding more fuel tanks always increases range. In reality, fuel tanks add mass, which increases fuel consumption. There is an optimal balance between fuel and oxidizer, and a calculator helps find it. Also, cargo modules reduce range because they add mass without contributing to propulsion.

Finally, note that the game’s range display is rounded and may not reflect the exact maximum. Always add a small safety margin (e.g., 10% extra fuel) to avoid falling short.

How to Choose a Rocket Calculator

When selecting an ONI rocket calculator, look for one that:

• Includes all three engine types and their exact efficiencies.
• Lets you input the number of tanks and cargo modules.
• Outputs both required fuel/oxidizer and maximum range.
• Is updated to the current game version (rocket mechanics have changed in patches).

Most calculators are free web apps or spreadsheets. Check the comments or forum posts to see if other players confirm accuracy. Since the game is still updated, a calculator from a few years ago may be outdated.

Costs and Resource Planning

Rocket fuel and oxidizer are not cheap. Steam can be produced from water, but petroleum requires refining oil, and hydrogen requires electrolysis and cooling. A calculator helps you plan how much to produce and store before launching. For example, a trip to a distant asteroid might require 2,000 kg of petroleum and 1,000 kg of liquid oxygen. Knowing this in advance lets you set up the necessary production chains.

Also consider the cost of building the rocket modules themselves. Cargo bays and fuel tanks require refined metals and other materials. A calculator can help you decide if a mission is worth the resource investment.

Safety and Accuracy Tips

While there is no real-world danger in a game, accuracy matters for gameplay. Always double-check your input values (engine type, tank counts) because a single wrong digit can ruin a mission. Use the calculator’s output as a guideline, not an absolute guarantee, because the game may have rounding differences.

If you are using a calculator that requires you to input fuel and oxidizer separately, remember that the ratio matters. Too much fuel and too little oxidizer will waste fuel; the calculator can help you find the optimal ratio.

For beginners, start with short-range missions and use the calculator to see how the numbers work. As you get more comfortable, you can rely on it for complex interplanetary trips.

Alternatives to Rocket Calculators

If you prefer not to use an external calculator, you can do the math manually using the game’s data. The formulas are known and posted on the game’s wiki. However, this is tedious and error-prone, especially with multiple modules.

Another alternative is to use in-game mods that display exact range and fuel requirements. These mods are popular but require installation and may not work with all game versions. The official game UI only shows a rough range bar, so a calculator or mod is recommended for serious space exploration.

Frequently Asked Questions

Q: Do I need both fuel and oxidizer for a rocket to launch?
Yes, both are required. The engine burns fuel with oxidizer to produce thrust. Without oxidizer, the rocket won’t ignite.

Q: What is the most efficient engine in ONI?
The Hydrogen Engine is the most efficient, giving the most range per kg of fuel and oxidizer. However, it requires liquid hydrogen and liquid oxygen, which are difficult to produce and store.

Q: Can I use a rocket calculator for modded rockets?
Most calculators are designed for the base game. If you use mods that add new engines or modules, the calculator may not be accurate. Check if the calculator supports modded content.

Q: Why does my rocket run out of fuel even though the calculator said it would make it?
Possible reasons: you entered the wrong engine type, forgot to account for cargo mass, or the game’s range display is slightly different. Always add a 10% safety margin.

Q: Is there an official rocket calculator from the game developers?
No, Klei Entertainment does not provide an official calculator. The community-made ones are based on data mined from the game and are generally accurate.

Q: How do I find the distance between asteroids?
The in-game starmap shows distances in tiles when you select a destination. You can also use the map’s grid lines to estimate.

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in fuel | Fuel (kg) | kg | 1000 | 0 | 100000
in ox | Oxidizer (kg) | kg | 600 | 0 | 100000
in eng | Engine type | - | Steam=1, Petroleum=2, Hydrogen=3 | 1
in dist | Distance | tiles | 10000 | 0 | 1000000
out range | Max range | tiles | (fuel * 10 + ox * 5) * eng | 0
out burn | Burn time | cycles | (fuel + ox) / 200 | 1