Is my number normal?

Blood oxygen level chart: what's normal by age, asleep and at altitude?

By GyroscopeUpdated November 15, 20268 sources

Awake and resting, 95 to 100 is normal at every adult age. A watch’s night average runs about a point lower, age barely moves either number, and where you live moves them most. The four charts below cover awake, asleep, age and elevation, worked out from 33,080 Apple Watch wearers and the US guidance.

Many blood oxygen charts online are one table with a range for each age, and the numbers fall a lot as the ages climb. Few of them say where the numbers came from, or whether they mean awake or asleep, a finger clip or a watch. Those details change the answer more than age does. An 88 at 3 am and an 88 at breakfast are different events, and moving from the coast to Denver changes your night more than 20 birthdays.

Chart 1: awake and resting

These lines are from MedlinePlus, the US National Library of Medicine’s health site, for a finger oximeter at rest. They’re the same at every adult age.

If your skin is darker, a finger oximeter that shows 88 to 95 can hide a lower true number. In hospital patients whose oximeter showed 92 to 96, a blood test found true oxygen under 88 for 11.7% of Black patients’ measurements and 3.6% of White patients’. Go by how you feel when the two disagree.

Chart 2: awake, a night’s average and a night’s lowest point

A watch or ring can show three different kinds of number, and each has its own normal. In 33,080 Apple Watch wearers the night ran about 0.8 points under the day. The lowest point of a healthy night goes much lower, and in 350 people with normal sleep studies it averaged about 90.

Chart 3: by age

Age moves the number very little. In the Apple Watch study, 20 more years took under 1 point off a typical night. Here are the typical ranges for each decade, for a watch at sea level, covering about 95 in 100 wearers if the spread is normal.

The day column is a watch’s background checks while you sit still, and the night column is its overnight average. For a finger oximeter at rest, use Chart 1 at any age. What’s a normal blood oxygen for my age? has the study behind it.

Chart 4: by elevation

Elevation moves the number most. Air is about 21% oxygen everywhere, but the pressure falls as you climb, so each breath carries less. Every kilometre (3,300 feet) higher people lived took about 1.2 points off a typical night.

The table stops at 8,000 feet, because the study’s straight line bends above about 8,200 feet and normal numbers higher up are a wide range, as two altitude doctors wrote in 2011. Up there, the CDC says people with altitude sickness usually show a number that’s normal for the altitude, so symptoms decide. What’s normal blood oxygen at altitude?, Denver’s numbers and oxygen by elevation go further.

How to use the charts

• Find your number’s kind first. Awake on a finger clip, a night’s average or a night’s lowest point.
• Then your elevation. If you sleep above 5,000 feet, the age table runs a little high for you.
• Then your own nights. These charts come from one watch model in US wearers. Your usual nights on your own device are the better yardstick.

Every number from 85 to 100 shows any number all three ways, and Your number, explained works it out for your age, device and elevation.

Children’s numbers differ, so ask your child’s doctor.