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Martin Ruegner, Getty ImagesThe atmosphere of the Earth has a different composition from that of other planets in part due to the biochemical reactions of Earth's organisms. Trees and plankton play a big role in this. You've probably heard that trees produce oxygen, but have you ever wondered how much oxygen that is? You'll hear a range of numbers and ways of presenting them because the amount of oxygen produced by a tree depends on the species of tree, its age, its health, and also on the tree's surroundings. According to the Arbor Day Foundation, "a mature leafy tree produces as much oxygen in a season as 10 people inhale in a year." Here are some other quoted figures regarding the amount of oxygen produced by a tree:

"A single mature tree can absorb carbon dioxide at a rate of 48 lbs./year and release enough oxygen back into the atmosphere to support 2 human beings."
- McAliney, Mike. Arguments for Land Conservation: Documentation and Information Sources for Land Resources Protection, Trust for Public Land, Sacramento, CA, December, 1993

"One acre of trees annually consumes the amount of carbon dioxide equivalent to that produced by driving an average car for 26,000 miles. That same acre of trees also produces enough oxygen for 18 people to breathe for a year."
- New York Times

" A 100-ft tree, 18" diameter at its base, produces 6,000 pounds of oxygen."
- Northwest Territories Forest Management

"On average, one tree produces nearly 260 pounds of oxygen each year. Two mature trees can provide enough oxygen for a family of four."
- Environment Canada, Canada's national environmental agency

"Mean net annual oxygen production (after accounting for decomposition) per hectare of trees (100% tree canopy) offsets oxygen consumption of 19 people per year (eight people per acre of tree cover), but ranges from nine people per hectare of canopy cover (four people/ac cover) in Minneapolis, Minnesota, to 28 people/ha cover (12 people/ac cover) in Calgary, Alberta."
- U.S. Forest Service and International Society of Arboriculture joint publication


December 15, 2010 at 10:36 pm
(1) Dr. Henry says:

I don’t want to sound rude, but your calculations are either meant to be missleading or you have no clue what you are talking about.

” A 100-ft tree, 18″ diameter at its base, produces 6,000 pounds of oxygen.”

I’m assuming that is true. But that same tree will also consume (get rid of) 8251.875 (8000 to significant figures) pounds of carbon dioxide. The Math at the end.

An average human consumes 550 liters of oxygen daily, which is 631 lbs a year, (density of oxygen is 1.46 g per liter), so that same tree could support almost 10 people, not two.

Basically that one 100 ft tree would consume 1.33 pounds of CO2 for every 1 pound of oxygen it creates, and will support 10 people yearly.

“A single mature tree can absorb carbon dioxide at a rate of 48 lbs./year and release enough oxygen back into the atmosphere to support 2 human beings.”

Must be a tree the size of a peace of paper. That same tree would produce much less oxygen. and would support less than one person a year.

6000 lbs of O/2.2 (convert to kilograms), *1000 (convert to grams) / 32 (convert to moles of oxygen) (in the photosynthesis reaction that trees do to create energy but also oxygen, the balanced equation is 6CO2+6H2O–>C6H12O6+6O2) so for every mole of oxygen there is one mole of carbon dioxide, so take the answer from before (85227.27 mol O) convert it to mols CO2, (which is the same number) times by molar mass of CO2: 44.01g, divide 1000 (to convert to kilograms of CO2) times by 2.2 (convert answer into pounds) = 8251.875 pounds of Carbon Dioxide per year. Because the original number being worked with was 6000, which is only 1 significant figure, only one carries over, so 8251 becomes 8000.

Theres the math, kind of confusing written like that, but thats the best I can do with typing in a text box.

June 11, 2011 at 3:34 am
(2) Mark joseph says:

What???! Your opening statement: “I don’t want to sound rude, but your calculations are either meant to be missleading or you have no clue what you are talking about.”

The author has not made claims, but quoted other well respected authorities. You should know that!

You don’t want to sound rude? You couldn’t sound more rude if you tried and you are not even aware of it? It throws all your claims of logic into doubt from the first base.

A very interesting article and worthy of ‘adult’ discussion.

June 29, 2011 at 12:35 pm
(3) Maria says:

If you notice she actually just found information from other sources and quoted it because her first quote from Arbor Day Foundation states exactly what you said 1 healthy tree can produce oxygen for 10 people for a year. My whole grip is why don’t people see all these figures that are great ones instead of just all the bad. Work something out with the good instead of complaining about all the bad in the world. Great information everyone.

December 15, 2010 at 10:57 pm
(4) Dr. Henry says:

“On average, one tree produces nearly 260 pounds of oxygen each year. Two mature trees can provide enough oxygen for a family of four.”
- Environment Canada, Canada’s national environmental agency

Using the same formulat above, that ‘average tree would consume 360 pounds of carbon dioxide each year. You would need 3 of those trees to support one person. It would not support two by itself like you said.

” A 100-ft tree, 18″ diameter at its base, produces 6,000 pounds of oxygen.”

Say that a collection of those trees filled one entire hectare with 100% canopy cover, I’m assuming that the canopy if viewed as a circle will have a diameter of about 20 feet. so the area that covers is pi*10^2= 314.159 square feet which is equal to 29.20 meters squared. 1 hectare is equal to 10000 square meters so, one hectare would have aproximately 342 of these trees (10000/29.2). As mentioned above, one of those trees produces 6000 lbs of oxygen, so 342 times 6000= 2052000 pounds of oxygen. One human needs about 631.5 pounds of oxygen a year (mentioned in last comment) so 2052000/631.5. Thats 3249 people, not 19. Now unless im missing something really big, this article is complete bs. I’m srry, please correct me if I’m wrong, im ready to learn. :)

June 18, 2011 at 8:32 am
(5) chandra mani aryal says:

Dr. henry i’m not a talanted person like you but i think i would like to ask to you that if a tree produces the oxygen nearly about 6000 pounds of oxygen. Very large portion of it is used by plant during respiration so the actual production is much more less than expected. It’s only my thought not the finding of the research. I could be wrong too.

August 18, 2011 at 1:35 am
(6) Joe says:

Now I believe the real question is not how much CO2 the tree absorbs but how much O2 it produces. Do the math again and try to make it a little more simple Dr. Henry, a human consumes approximately 6-8 lbs of oxygen a day ( right now I’m going to meet it in the middle at 7), so 7*365=2555 per year. Now, I’m not an expert on trees but if a 100-ft tree 18″ at the base produces about 6000 lbs every year, it would be able to produce enough oxygen to support 2.34833659 …. people.

May 22, 2011 at 1:30 pm
(7) Mr. Nobody says:

Great display of figures and math, and I appreciate it.
If someone wants to account for the approx amount of trees on Earth, please don’t forget to add in the other beings that share the Earth with humans, i.e. animals, insects, germs.
Even the weather relies on air and its density thereof.

April 6, 2012 at 3:51 am
(8) talon0409 says:

Umm I think we are all a bit on a hit and miss here. You all keep converting to Pounds and liters and so on which id baffling bc you are making a lot of assumptions (which is bad). when dealing with an ideal gas under standard conditions it goes PV=nRT (pressure x volume=# of moles x gas constant x temp) but seeing as how our surroundings are NOT standard then these converstions are pointless. When doing the math just keep it simple and stick with like units.

April 30, 2012 at 8:28 pm
(9) Diplomacy says:

Joe, double check your units.

The average person consumes between 6-8 LITERS of O2, not pounds. if you make the conversion yourself using dr henry’s formula supplied above, you’ll get the correct figures…


September 25, 2012 at 11:09 am
(10) casual observer says:

I believe we all need to be careful when taking one piece of information and substituting it in another equation without being certain that the two are able to be used interchangeably. For example “On average, one tree produces nearly 260 pounds of oxygen each year. Two mature trees can provide enough oxygen for a family of four.”
- Environment Canada, Canada’s national environmental agency
An average tree may produce 260 pounds of oxygen a year and two mature trees enough oxygen for a family of four. But where does that say two average trees can support a family of four. An average tree and a mature tree are not the same thing. Many trees are young and die or are cut down before becoming mature. So clearly the average tree must be much smaller and produce much less oxygen than a mature tree.
This is just one example of using facts from one area to then make a conclusion in another area where it sounds correct because we can agree on the first item but the logic to apply it to the result is flawed.

October 5, 2012 at 3:30 pm
(11) jL says:

what i do not understand , surely the thee produces sugar, leafs, wood from all this Co2 it absorbs, and one day it uses the sugar up, the leafs fall down, de-compose and the wood gets burnt or rots, all these procresses release CO2, or consume O2, and in history plants could only act as sink for C)2 becasue they were transformed into oil/coal, before we burnt it, so how does a normal tree, which will not be transformed into coal, add to all this?


December 9, 2012 at 5:19 pm
(12) Will Dolezal says:

When they say a human being needs? Are they only taking into account breathing? What about other actions that generate carbon dioxide, such as heating?

January 16, 2013 at 2:22 pm
(13) Othellobrown says:

Just thinking out side of the box here, but if trees are the key to stopping global warming, can anyone tell me why or if they are working on producing trees that sprout like geo pets and able to reach maturity in one to five years, or giant leaves ten times the size of normal leaves, I’m sure they have the technology to do it, cause I’ve seen chickens as big as turkeys,giant pumpkins and tomatoes, so why don’t they make enough giant leave trees to consume all the pollution????

February 10, 2013 at 7:12 am
(14) Dude says:

All this wasted energy blah blah blah go outside and plant a tree. I’m researching trees in general but mainly the history and the affects thereof. Stunned, amazed, love and respect sum up my studies thus far. I challenge all to go hangout with a tree and give it a name.

June 10, 2013 at 4:28 pm
(15) sirion says:

Don’t forget the dark phase but what if there is a tree that does not release carbon dioxide in the dark phase, what if it could handle drought conditions and wet conditions and 1 hectare is equivalent to a rainforests potential to absorb co2, its called a Portulacaria afra (spekboom) from the Eastern Cape, South Africa, can be propagated from cuttings directly in to soil.

September 27, 2013 at 3:07 pm
(16) Loren says:

Dr. Henry’s math is very informative and I am happy to know that there is a way to calculate how much oxygen a tree produces as well as how much oxygen a human consumes. However, I have to agree with Maria and Mark Joseph that Dr. Henry’s reply was rude and negative when it would have been much better had he merely given us the facts about how to actually calculate the numbers. He might even have gone so far as to thank the author for searching out some sources on the subject and then gently show how one would do the calculations.

October 11, 2013 at 6:10 am
(17) Alexey says:

I’m not an expert in tree metabolism, but essentially the tree captures much more carbon while it’s growing, not when it is mature. When it is growing, it needs carbon to build up the tree mass, and hence consumes a lot of CO2. But when it’s mature (doesn’t grow in size any more), it needs CO2 basically to grow leaves. So, when calculating how much oxygen a tree generates, one should rather to look at a tree at it’s maximum growth rate.
Another way to calculate the average tree CO2 capture is to take a mature tree trunk weight, divide by it’s age and infer the amount of carbon from timber chemical composition. That would bee a good way to double-check the numbers.

November 18, 2013 at 11:49 am
(18) Ned says:

Don’t the majority of trees grow faster in warmer conditions? I think of Stradivarius violins and how he used slower growing trees during the mini iceage to obtain the perfect pitch. Also, what happened to the molecules of Caesar’s last breath once he exhaled? Did the trees essentially scrub them clean, converting it back into breathable air? I’m a novice when it comes to chemistry and math, just some thoughts that popped in my head

December 21, 2013 at 1:46 am
(19) Somendramohan Ghosh,Geen technologist says:


January 1, 2014 at 9:16 pm
(20) William Fleming says:

Trees do NOT make oxygen through photosynthesis. They make sugar for their own use. A plant cell and animal cell are alike–both oxidize sugar. For every atom of oxygen split off using the sun’s energy, there is an oxygen atom recombined somehow, someday, either in the plant itself or in the cells of animals who eat the plant. Every carbon atom in a tree’s trunk converts to CO2 when the tree burns or rots, using the exact amount of excess oxygen released during the life of the tree. It’s the Conservation of Mass and Energy, a law of nature ignored by many in all the environmental ballyhoo. Mature trees not growing contribute NO excess oxygen.

January 3, 2014 at 5:30 pm
(21) Krusatyr says:

<b>Planting the right trees</b> (never ever plant Eastern Red Cedar, kill them off) in the right place to reforest stressed environments can have many positive repercussions in addition to releasing O2 and storing the carbon.

Tree lines and forests can restore top soil and water tables, slow evaporation, enable other flora and fauna and increase resources for balanced use.

Reforestation can be a mostly privately financed program, kept at local and State levels, outta the hands of Central Planning, who would use it for raising taxes, hammering free enterprise and limiting freedom.

January 4, 2014 at 10:08 pm
(22) William Fleming says:

I’m with you Krusatyr on the value of trees. But please explain what is wrong with Eastern Red Cedars. There are a lot of them on my place. Even loggers in this area

will leave them standing when clear cutting because they are considered special.

January 23, 2014 at 4:49 am
(23) Jacob Edrei says:

To Dr. Henry:

You forgot that green plants (green trees are included) breath Oxygen during the night and release Carbon dioxide to the atmosphere.

Sorry pall but you made a mistake in your calculations.

March 20, 2014 at 9:10 pm
(24) Armando Landa G. says:

Dr. Henry, please give sources.
Is there a University doing research regarding?

This is an evidence urbanists and government should know about from truthfull source.

April 2, 2014 at 1:18 pm
(25) Starshiptrouter says:

Science is rude to me every day as it is to millions of scientists and engineers in many fields. Its sharp sword keeps me honest. I love the sting of truth more than comfortable falsehoods.

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