For the past several posts we’ve been talking about calculating TPO using dissolved oxygen values on shaken packages. Now let’s go for it, and talk about the calculation itself.

The standard reference TPO calculation in use today first appeared in a 1985 article in *Brauwelt*. There’s a lot of math behind this, so if you want to really understand all of the parameters then it’s well worth looking up: C. Vilachá and K. Uhlig, “The Measurement of Low Levels of Oxygen in Bottled Beer,” *Brauwelt International *(Volume 1, 1985), 70-77.* *In the meantime, let’s dissect the calculation and then talk about how you can get an excellent approximation of the TPO using your dO_{2} measurement. Here’s the equation:

m (t) = total oxygen in mg

X = oxygen content of the beer mg/L (or ppm dO_{2})

T = Temperature degrees K

The table below shows the dO_{2/}TPO Ratio multiplier you need to apply to your dO_{2} to get your TPO. As you will see in the table, the multiplier or dO_{2/}TPO Ratio is very dependent upon the package temperature and headspace volume.

Package Type |
Liquid Volume (mL) |
Headspace Volume (mL) |
Temperature Degrees C |
dO_{2}/TPO Ratio |

12 Oz. |
355 |
17 |
5 |
2.1 |

12 Oz. |
355 |
22 |
5 |
2.4 |

12 Oz. |
355 |
17 |
20 |
2.4 |

12 Oz. |
355 |
22 |
20 |
2.9 |

22 Oz. |
651 |
25 |
5 |
1.9 |

22 Oz. |
651 |
25 |
20 |
2.2 |

22 Oz. |
651 |
35 |
5 |
2.2 |

22 Oz. |
651 |
35 |
20 |
2.6 |

So let’s pick an example from the above table, and do our calculation. If you have a 12 oz. package with a 17 mL headspace and you are measuring at 5 degrees C, multiply your dO_{2} by the ratio of 2.1 to get your TPO. We’re using 100 ppb (0.100 ppm) in this example.

dO_{2} x dO_{2}/TPO ratio = TPO such that 0.100 mg/L x 2.1 = 0.210 ppm TPO

My final thought is that if you have tight TPO specifications or really want to track everything back to a LIMS system, then a TPO analyzer is the right choice. Otherwise, using a calculator in an excel spreadsheet will get you an equally accurate concentration if you know which parameters are important.

*If you would like a copy of a TPO calculator that works in excel, leave a comment and I will email one to you.*

I would be very interested in the Excel calculator if you could send a copy. My brewery is putting together TPO testing and there is a surprising amount of information on the subject that falls somewhere between lore and BS, so these posts are quite helpful. Thanks a lot.

and here is the meat! Finally! I need to revamp my excel calculator.

I would be thrilled if you would share your excel sheet for TPO. This method of calculating TPO seems far superior then our current caustic shake method for determining “air”. Thank you for posting this information.

Could you please send me the calculator? Thanks for the article!

This is a great site, I just found it, I would really appreciate the calculator please!

Thank you!

Thank you very much for all information you share. I’d like to get a copy of your excel spreadsheet if possible. Cheers!

Thank you for the post. I’d be interested in the excel calculator as well. Thank you

I would be interested in a copy of the calculator as well if you don’t mind. Thanks!

Could you please send me the calculator? Do you have a copy of Vilachas’s article.

Thank you!

Could you please send me a copy of the Excel Calculator ? Thank you.

Could you please send me a copy of the TPO calculation that works in excel

Thanks for the informative posts. Would you please send me a copy of the Excel calculator? Thanks.

Hi Chaz, I really like the way you’re talking about DO, TPO,… in such a practical way. I’m very intrigued by the TPO calculation: could you please send me an excel-copy of the calculator? Thanks a lot!

Interesting information’s. Please send a copy of your excel spreadsheet if possible. Cheers!

Can you send an excel files of this TPO calculation. I have a Hach 3650 instrument that needed TPO calculator. Thanks!

Good day Chaz. can you send an excel calculator to my email. I have a Hach instrument that needed the TPO calculator. Thanks!

Kindly share with me that excel calculator

Hi, I’m new to the brewing industry, so forgive me if the answer to this question is obvious, but…how do you accurately measure the headspace volume?

There are two ways to check for HS volume. Cans can be weighed and then and the volume can be calculated from the overflow volume.

Total Weight – empty can weight = content weight. Content weight X product density = liquid volume. Overflow volume – liquid volume = headspace volume. The overflow volume is provided by the can manufacturer.

Bottles are easier to estimate. The ASBC method can be used, but for TPO calculation purposes there are simpler ways. The ASBC method involves weighing the contents and bottle and then filling the bottle with water to get the overflow volume, then subtracting the bottle weight from the total weight to get the content weight, multplying that by the density to get the content volume and subtracting it from the water weight.

What I do is estimate the average HS volume with ten cold beers by taring one on a scale, adding water from a squirt bottle until it’s full and assuming that the water weight is the same as the headspace volume. I then average the ten to look for statistical spread and assume that it is representative of the filler.

Hi again Chaz – May I have a copy of your excel spreadsheet? (I tried to construct my own, but must have units wrong or a misplaced parenthesis.) Thanks!

Thanks!

Hi!Can you please send me a copy of the calculator?I have 1 question also please!Can I calculate the foreign gas content with this method?We still use the old method with the KOH and we want to move to this one!

I’m not sure what you mean by the “foreign gas content”. Can you explain what you need to know?

Chaz, I would much appreciate a copy of your excel calculator for TPO.

I would also like a copy of the workbook. Thanks!!

I would appreciate if you could send me the excel calculator! Many thanks, Markus

If I understand correctly, O2 readings from shaken packages don’t have much comparative value, because the dissolved O2 reading depends on the temperature and headspace of each respective sample. Or am I missing something? I guess I don’t really understand what TPO means. If my TPO is 0.210ppm, that parts per million- of what? Is it on a volumetric basis, assuming the O2 was evenly distributed between the liquid and the headspace?

And yes, I would love a copy of the spreadsheet. You Blog is fantastic!

Cullen Dwyer

QA Manager, Wachusett Brewing Co,

I would like a TPO calculator in excel sheet…

i would like to get the TPO calculator..it would help me to understand the calculation.so plz send a copy.

I’d also like a copy of the calculator if possible! Thanks!

Can you please send me a copy of the calculator. Thank you,

I’d be very interested in the TPO calculator. If you can email it to me that would be perefct

Hi there,

Have a TPO calculator, but I would really like to see the differences between the one we have compared to this model. Question: Would the theroy behind this also work the same for Packaged Cider?

Chaz,

I have really enjoyed your blog posts. Thank you for being so transparent with your knowledge. We employ both a 3650 and 3625 in our QA. I would like to review your TPO calculator if you are still able to send it our way.

I would appreciate a copy of the Excel calculator. Thank you.

Can you please send me a copy of the Excel TPO calculator?

That was some very intereseting reading. I would also appreciate it if you sent me the excel calculator.

Hello-

If its still available, I’d like a copy of the excel calculator. I tried my hand at making my own, but for some reason could not use that equation to match the sample numbers you’ve published in your examples. Thanks for the help!

Hi Chaz,

I would like a copy of the Excel calculator..thanks..

Hi Chaz,

I would like a copy of the Excel.

I woul like to know if the formula is the same for soft drinks

Thank you

Hi Chaz. Great information on dO2 and TPO. I would like a copy of the Excel calculator if possible.

this series of posts about TOP and dO2 has been super informative and incredibly helpful. I would love to get a copy of the TPO calculator for Excel.

Cheers!

Hi Chaz,

Thanks for posting this, would it be possible to get a copy of the excel calculator?

I would like a copy of the calculator please

Still possible to get a copy of the excel calc? Thanks!

i would like the TPO excel calculator, im working in a brewery and we have discussions about the low parameters measured in our bottles, about 25 – 30 ppb and our TPO is 20 ppb less than our dissolved O2. Considering we are using antioxidant. is it possible..??

Hello, could you send me a copy of the exel calc, too?

I’d love a copy of the TPO calculator. Thanks!