Oxygen level by age

How to read the chart

• SpO2 awake is a resting spot check on a fingertip oximeter.
• SpO2 asleep is the average or median for the whole night. It is not the lowest point of the night, which is always lower.
• Sleeping heart rate is the average for the night in beats per minute.
• Each range says what it is: the lowest to highest value seen in the study, a percentile range, or the mean plus or minus 2 SD. Open an age band to see which.
• The ends of a range count as within it.

What the studies show across ages

Healthy infants and children sit in a narrow band overnight. Terrill and colleagues recorded healthy infants in a sleep lab and found overnight medians between 95% and 100% in the first six months, and between 96% and 100% at ages 1 and 2. Urschitz and colleagues recorded 90 primary school children at home and put the 5th centile of the overnight median at 97%.

Adults spread wider. Gries and Brooks studied 350 healthy people aged 1 month to 85 years in a sleep lab. The overnight median averaged 96.5% across all ages and 95.1% in the over-60s. A 2019 meta-analysis of sleep-lab studies by Boulos and colleagues found the same direction: an average overnight saturation of 96.2% at ages 18 to 34, 95.3% at 35 to 49, 94.3% at 50 to 64 and 93.3% at 65 to 79.

Awake readings follow the same pattern. In the Tromsø survey of Norwegian adults, 94.7% of those under 60 read 96% or higher at rest. That share was 89.1% at ages 60 to 70 and 84.5% at 70 and over.

Sleeping heart rate falls through childhood. Archbold and colleagues measured an average of 73.6 bpm in boys and 77.6 bpm in girls aged 6 to 11. In adults aged 50 to 65, Persson and colleagues found the average between 22:00 and 06:00 ran from 48 to 83 bpm. For more on overnight pulse, read what your overnight heart rate shows.

Why your reading can differ from a study

• The device. Consumer oximeters carry a stated error of a few points. The oximeter accuracy range tool shows how wide that is for one reading, and why a reading might be wrong lists the common causes.
• Altitude. The ranges are not adjusted for elevation. SpO2 is lower in thinner air, so use the altitude oxygen calculator if you live or travel high up, or oxygen on a plane for a flight.
• The setting. Most of the sleep figures come from one night in a sleep lab. A night at home, on a different sensor, is not the same measurement, and home oximetry is not a sleep study.
• The statistic. Some studies report the median for the night and some the mean. Check which one your app shows before comparing.
• One night. A single recording moves with sleep position, alcohol and a blocked nose. Use compare nights to put several recordings side by side.

How to get an overnight average

A fingertip spot check gives the awake figure only. For the sleep figures you need a device that records all night. Load the file into the free session viewer to get the average SpO2 and heart rate for the night, or type the numbers from a report into the oximetry results explainer. How a pulse oximeter shows what is happening to your sleep covers what an overnight recording contains, and how to read your O2Ring report shows where each figure sits on a Wellue report.

Where the ranges come from

Every range is taken from a published study of healthy people or, for awake adults, a general population survey. Where a study prints a mean and SD but no range, the range here is the mean plus or minus 2 SD, worked out from the published figures. Each age band in the tool states which it is and who was studied.

Some age bands have no range. No study was found with an awake SpO2 range for healthy children under 5, teenagers past 14 or adults under 40, an overnight SpO2 range for teenagers, or a sleeping heart rate range outside ages 6 to 11 (the 50 to 65 figure below sits in a note). Those cells are left empty, and the tool shows the nearest pooled average in a note.

Common questions

Does blood oxygen fall with age?

On average, a little. In a sleep-lab study of 350 healthy people the overnight median SpO2 averaged 96.5% across all ages and 95.1% in the over-60s. In a Norwegian population survey, 94.7% of adults under 60 read 96% or higher awake, against 84.5% of those aged 70 and over.

What oxygen level do studies report for a 70 year old?

Awake and at rest, 98.1% of adults aged 70 and over in the Tromsø survey read 93% or higher on a fingertip oximeter. Asleep, the overnight median in healthy over-60s averaged 95.1%, and the mean plus or minus 2 SD runs from 91.1% to 99.1%.

Is a child's sleeping oxygen level different from an adult's?

The published ranges for children are narrower and sit higher. Among 90 primary school children recorded at home, the overnight median ran from 97% at the 5th centile to 100%. The adult range from the sleep-lab study used here is 93.5% to 99.5%.

Why does the chart use the overnight average and not the lowest reading?

The studies used here report the overnight median or mean, so that is what can be compared. The lowest reading of a night is a single sample that depends on how the device averages its signal and on movement, so it differs more from one device to the next.

Why are some cells empty?

No study with a range for healthy people of that age was found. That covers awake SpO2 for children under 5, teenagers past about 14 and adults under 40, overnight SpO2 for teenagers, and sleeping heart rate outside ages 6 to 11. The tool shows the 50 to 65 figure in a note, and leaves a gap and shows the nearest pooled average in a note.

My reading is below the range. What should I do?

Check the reading first. Warm your hand, sit still for a minute and take it again, or record several nights and look at the average. If your readings stay below the range, take the recordings to a doctor. The range describes other people and says nothing about the cause of your reading.

Sources

1. Terrill PI, Dakin C, Hughes I, Yuill M, Parsley C (2015). Nocturnal oxygen saturation profiles of healthy term infants. Archives of Disease in Childhood 100(1):18-23.
2. Elder JW, Baraff SB, Gaschler WN, Baraff LJ (2015). Pulse oxygen saturation values in a healthy school-aged population. Pediatric Emergency Care 31(9):645-647.
3. Urschitz MS, Wolff J, Von Einem V, Urschitz-Duprat PM, Schlaud M, Poets CF (2003). Reference values for nocturnal home pulse oximetry during sleep in primary school children. Chest 123(1):96-101.
4. Archbold KH, Johnson NL, Goodwin JL, Rosen CL, Quan SF (2010). Normative heart rate parameters during sleep for children aged 6 to 11 years. Journal of Clinical Sleep Medicine 6(1):47-50.
5. Van Eyck A, de Caen G, Bokhaut J, et al. (2026). A systematic review and meta-analysis of polysomnography parameters in healthy children. European Respiratory Review 35(180):250224.
6. Gries RE, Brooks LJ (1996). Overnight oxyhemoglobin saturation in 350 healthy people aged 1 month to 85 years. Chest 110(6):1489-1492.
7. Boulos MI, Jairam T, Kendzerska T, Im J, Mekhael A, Murray BJ (2019). A systematic review and meta-analysis of polysomnography parameters in healthy adults. The Lancet Respiratory Medicine 7(6):533-543.
8. Vold ML, Aasebø U, Wilsgaard T, Melbye H (2015). Low oxygen saturation and mortality in an adult cohort: the Tromsø study. BMC Pulmonary Medicine 15:9.
9. Shapiro I, Stein J, MacRae C, O'Reilly M (2023). Pulse oximetry values from 33,080 participants in the Apple Heart & Movement Study. npj Digital Medicine 6(1):134.
10. Persson AP, Måneheim A, Economou Lundeberg J, et al. (2024). Reference ranges for ambulatory heart rate measurements in a middle-aged population. Heart 110(12):831-837.