Dissolved oxygen converter

Convert dissolved oxygen between mg/L and percent saturation. Pick the water temperature: cold water holds far more.

Dissolved oxygen

From To

54.79%

Water temperature

That's about the same as a healthy river. That is healthy, well-oxygenated water.

What it means

How much oxygen is in there?

Saturation values are for fresh water at sea level. Seawater holds about 20% less, and altitude lowers it further.

Every unit

Your reading in every unit

Learn

Warm water holds less

Saturation falls from 14.6 mg/L at 0 °C to 7.6 at 30 °C. A summer heatwave can halve what a river can carry.
Why percent saturation matters

8 mg/L is 70% saturation in cold water but over 100% in warm. The percentage says whether the water is gaining or losing oxygen to the air.
Above 100% is real

A weedy pond on a sunny afternoon can reach 150% as plants pump out oxygen faster than it escapes. By dawn the same pond may be down to 30%.

Background

Fish breathe the oxygen dissolved in water, and there is not much of it: 8 mg in a liter against 280 mg in the same volume of air.

Cold water holds more — 14.6 mg/L at freezing, 7.6 at 30 °C — which is why warming rivers suffocate fish even when nothing else changes.