oni geyser calculator

What this ONI geyser calculator solves

In Oxygen Not Included, geysers and vents never output steadily forever. They erupt in bursts, then go quiet, then become dormant for many cycles. That makes “headline” output numbers misleading. This tool helps you convert the raw in-game stats into practical planning numbers:

• Average output during active season (when the geyser is not dormant)
• Long-term average output (including dormancy)
• Storage needed to bridge dormant periods
• Estimated number of geysers to meet your target demand with safety margin

How the math works

1) Eruption duty cycle

Each geyser alternates between erupting and not erupting. If it erupts for 50 seconds every 100 seconds, the duty cycle is 0.5.

Duty cycle = active duration / eruption period

2) Active-season average

Multiply the eruption rate by duty cycle to get the average flow during active cycles.

Active-season average (g/s) = eruption rate × duty cycle

3) Long-term average including dormancy

A geyser that is active 70 cycles and dormant 30 cycles is only available 70% of the time. Apply that fraction to the active-season average.

Long-term average (g/s) = active-season average × (active cycles / total cycles)

4) Buffer for dormancy

Even a sustainable geyser still needs storage to survive dormancy.

Dormancy buffer (kg) = demand (g/s) × dormant seconds / 1000

If this is liquid, divide by 5000 to estimate the number of liquid reservoirs.

How to read your results

• If long-term average ≥ adjusted demand, your plan is sustainable on paper.
• If long-term average < adjusted demand, you will eventually run out unless you add another source.
• A positive long-term average is not enough by itself; you still need enough storage to ride out dormant stretches.

Practical planning tips

Use a safety margin

Add 5–20% overhead for pump uptime losses, imperfect automation, and temporary routing issues. The calculator includes a built-in margin input so your design is less brittle.

Separate generation and consumption loops

If your geyser feeds oxygen, farming, and cooling all at once, prioritize critical lines with valves and automation. Your colonists notice oxygen drops long before you notice a slick cooling issue.

Store where the phase is stable

Hot outputs can flash or freeze in the wrong area. Keep storage in temperature-safe rooms and only process after buffering. Stable storage is often more valuable than theoretical peak throughput.

Common mistakes this calculator helps avoid

• Designing for eruption rate instead of average rate
• Ignoring dormant cycles when sizing production
• Undersizing storage and crashing mid-dormancy
• Forgetting demand growth as duplicant count increases

Example workflow

Analyze your geyser in-game, then enter the values exactly as shown. Add your current demand and a margin. If results show “not sustainable,” either lower demand, add another source, or combine multiple geysers into one shared storage and distribution system.

For expansion planning, run the calculator again with your future demand target. This prevents expensive rebuilds once your colony scales.

Final note

This calculator is intentionally simple and fast. It gives strong first-pass planning numbers for water, polluted water, natural gas, hydrogen, and other periodic outputs. For advanced builds, pair these results with your thermal and material handling constraints.