No registration, no passwords; no pop-up ads -- just aloha, fun, & authoritative answers.
As an eBay Partner & Amazon Affiliate we receive compensation for qualifying purchases.
Home /
Search 🔍
the Site
pub  Where the world gathers for
plating, anodizing, & finishing Q&As since 1989


Conversion from Baumé to S.G.

Q. Hi,

Would someone tell me the formula for conversion from degree Baumé to specific gravity?

Thanks and Best Regards,

K F Quan
- China

A. SG= 145/ (145-Be)

sara michaeli
sara michaeli signature
Sara Michaeli
Tel-Aviv-Yafo, Israel

A. I have a similar formula, but as follows: = 146/ (146 - Be) Note that this is only accurate at 20 deg. C. The result from my formula will be slightly more accurate according to the published data from our sulfuric acid supplier, for these two related values. (Splitting hairs here.) Some hydrometers are graduated in either scale.

W. Carl Erickson
- Rome, New York

A. According to the CRC Handbook of Chemistry & Physics [adv: on Amazon & AbeBooks & eBay] of Chemistry and Physics, 145 is the correct number to use in the formulas already mentioned.

Jon Barrows
Jon Barrows, MSF, EHSSC
GOAD Company
supporting advertiser
Independence, Missouri

Q. Sir please explain the detail of the formula you have mentioned. What is 145 and how it is come.
Regards. Please also tell me detail theory of degree twadel and Baumé.
If you can provide a table of Baumé conversion I would be thankful to you

Raza Rahman
employee - Karachi, Pakistan
July 8, 2008

A. Hi there,

Here is the full conversion calculation,

SG = 141.5/(131.5+API)- for oils
SG = 140/(130+deg Baumé) - for liquid lighter than water
SG =145/(145-deg Baumé) - for liquid heavier than water

best wishes,

Ahmed Al-Terkait
- Kuwait - Arabian Gulf
July 29, 2008

A. I totally agree with Mr. Ahmed Al-Terkait.

But an educated Engineer should know there is no A R A B I A N Gulf in the world! It is always PERSIAN GULF and your money can't change the historical name which is far older than arabian countries like yours opinion!

Amir Ghods
- Tehran- Iran (North of Persian Gulf)
February 28, 2012

Q. What is 145 exactly, where did they base it?

Lawrence Rivers
- San Carlos, Phil
October 28, 2008

March 3, 2015

Q. Hi.

Baumé scale

I've a question:
I need to know what does number 145 exactly mean in the formula = 145/ (145 - Be) ... and where did it come from?
I need it as fast as possible .

All respect

Salee Al-Baradony
- Yemen ,Sana'a , Sana'a

A. Hi. 145 is just a number that works to convert degrees Baumé to Specific Gravity. The Wikipedia article explains the origin and purpose of the Baumé scale. Good luck.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
March 2015

March 6, 2015

Q. Mr. Ted Mooney,
Thanks a lot for your answer sir ...
still the question is about the number itself and not the Baumé scale or the formula.
It's about how do they get to put this number, not another number ... like why we use 145 for liquids heavier than water and use SG = 140/(130+deg Baumé) - for liquids lighter than water in the other formula..
Still looking for word to help as soon as possible.
Thanks again.

All respect

Salee Al-Baradony [returning]
- Yemen, Sana'a, Sana'a

A. Hello again Salee.

Sorry, but I don't think you are going to get satisfaction. As related in the Wikipedia article, the scale originally was based on the density of various amounts of sodium chloride dissolved in water at 16 °C. But as Wikipedia relates, the scale is inexact, vague, and ambiguous, so some handbooks cite 144 for the "heavier than water" scale, and other books cite 145, and other people cite 146. You're not going to be successful in putting a fine point on it because those constants are not based on any physical quantity, they are simply people's efforts to correlate an unreliable and vague scale to the more exacting S.G. scale. Good luck.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
March 2015

A. Hi Salee

As Ted says Baumé is "inexact, vague, and ambiguous". Even if you understand it, chances are that others will make mistakes.
The simple solution is to change to specific gravity (SG) - understood by all worldwide and no more mistakes in conversion.

geoff smith
Geoff Smith
Hampshire, England
March 9, 2015

Thanks for you both :
Mr Ted Mooney
Mr Geoff Smith
for your answers ..

All respect

Salee Al-Baradony [returning]
- Yemen, Sana'a, Sana'a
March 13, 2015

Q. Is there a way to determine which Baumé scale to use? Whether it is the lighter than water or heavier than water?

Marinela Alcantara
- Laguna, Philippines
February 25, 2016

February 2016

thumbs up signHi Marinela. I'm not a chemist, but I can do algebra, so I'd say --

Ideally the two equations would converge at S.G. = 1.0, such that:

S.G. = 1 = 140/(130+deg Baumé) = 145/(145-deg Baumé)

But they don't and can't converge,
because the first gives S.G. = 1.0 at a Baumé of 10, while the second gives S.G. = 1.0 at a Baumé of 0.

So I guess the answer is, try the "lighter than water" conversion factor, and if the answer comes out that S.G. > 1, then re-do the conversion with the other formula.
And if it then comes out that S.G. < 1, re-read Geoff's advice :-)


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

Chemicals &
Consult'g, Train'g
& Software

About/Contact  -  Privacy Policy  -  ©1995-2024, Pine Beach, New Jersey, USA  -  about "affil links"