How to compute age of gestation

0 Good day!
It's been 4 years since I graduated from nursing school and I have forgotten how to manually compute the age of gestation (no to calculators/ob wheels please).
I can't find a simple formula on how to compute it, google is just giving me results on how to do it via calculators.
I can't find my college notes too.
Can someone please help? Thanks 

1Jul 26, '11 by miss81Hope this helps...
Do you mean Naegele's rule for calculating EDC/EDD?
EDD = LMP  3 months + 7 days (obviously adjust year accordingly)
Or...
Are you referring to calculating gestational age from LMP?
"If the mother has a regular period and knows the first day of her last menstrual period, gestational age can be calculated from this date. Gestational age is calculated from the first day of the mother's last menstrual period and not from the date of conception. For women who have irregular menstrual periods or women who cannot remember the first day of their last menstrual period, it can be difficult to determine gestational age using this method. In these cases, an ultrasound exam is often required to determine gestational age. American Pregnancy Association
or...
We also us fundal height OR McDonald's Rule starting at 20 weeks gestation: Measure from
symphysis pubis to top of fundus.
http://1.bp.blogspot.com/_PqGgBbHMxF...ht_measure.jpgDoubleHelix likes this. 
0Jul 27, '11 by LorodzThanks for the replies. Not naegele's rule. I meant the age of gestation. Assume that the patient's LMP IS feb. 1 2010,the aog is 25 weeks and 2 days (thank u iPhone app) Back in nursing college, our professor gave us a simple formula to compute patients aog. I just forgot it now
Thanks for the ultrasound suggestion, but im in the ER and some patients just comein and doesnt have any aog based on ultrasound... So we have to resort to the unreliable AOG counting.
Thanks 
0May 26, '14 by IamsarahLeeIf an infant was born on 5/14 at 41 weeks and 4 days, would the EDC be 5/4? I'm not sure why I'm having a hard time with this. I do not know LMP?

0Apr 12 by lovelyjoanFor the computation of Age of Gestation, first determine the LMP for example you have given February 1, 2010. Then take note of the LAST CLINIC VISIT let's say the pregnant client visited the clinic for a prenatal checkup on July 30, 2010. Take note also that year 2010 is not a Leap year so there are 28 days for February.Add up the number of days for all succeeding months until the day of Last Clinic Visit.From LMP the computation is :
February 28
 1 (LMP is February 1 subtract this from complete number of days for February, or whatever is applicable month) February 27
March 31
April 30
May 31
June 30
July 30 (Last Clinic Visit)Sum total 179 days
To get number of weeks, divide the sum total with 7 using the long computation method. The remainder serves as the days.
So, 179 divided by 7 would give us 25 weeks and 4 days, approximately. 
0Apr 12 by klone, MSN, RNReally not necessary to bump up a 2 year old thread to answer a question that has long since been answered.

0Apr 16 by cayenne06, MSN, CNMwell now I want a handy formula to help me calculate gestational age! I'd be lost without my wheel.