Found the following info while looking around a civil war living history forum. Thought it might be of interest to some.

SPECIAL ORDERS, HEAD QUARTERS ARMY OF THE POTOMAC,
No. 65. Camp near Falmouth, Va., March 7, 1863.
* * * * * * *

In pursuance of Special Orders, No. 65, from headquarters Army of the Potomac, the board therein detailed assembled, and proceeded to make the experiment required, and arrived at the conclusion hereinafter stated.
In order to ascertain the amount of weight usually carried by soldiers in this army, average knapsacks were weighed, with the contents therein and blanket rolled on top, and the mean weight was found to be 15 pounds.
We then took out the contents of the knapsack, and packed inside ten days’ rations of hard bread, to wit:
Pounds.
100 biscuits and ten days’ sugar and coffee, and it then weighed, with blanket. 17
Without blanket 11¾
With a change of clothing—shirt, drawers, and socks. 18½
With coffee, sugar, and desiccated vegetables 20½
Three days’ rations of biscuit, bacon, and small-stores were put into a haversack, and it weighed – 5¾
The average weight of blanket 5¼
The average weight of overcoat 5¼
The average weight of half shelter-tent 1¾
The average weight of change of clothing 2

It was found that knapsacks would easily contain one hundred crackers, and that it was better to place at least as much as one shirt in the part of the knapsack next to the soldier’s back, in order that the biscuit might not chafe the skin, and that so long as a knapsack is carried neither the weight of the extra clothing nor the space occupied by it was sufficient to justify dispensing with the same; in fact, it can be carried better than not.
It is also to be observed that ten biscuits, although called a day’s ration, are not sufficient upon the march, when no other articles, such as beans, rice, and desiccated vegetables, are issued.
The board further placed five days’ rations of bacon in a haversack, with ten days’ coffee and sugar, and that amount was tried upon a soldier and worn without difficulty. But it should be here stated that the haversack is found, when loaded to its capacity, to fatigue the men in moderate or cold weather more than a knapsack with 15 pounds inside.
The board, after numerous experiments, and from their previous experience with troops in the field, agreed upon the following conclusions:
At a maximum, the men, by dispensing with extra clothing, except one extra shirt, drawers, and socks, can carry in their knapsacks one hundred biscuits and eight days’ small-stores, and, in the haversacks, two days’ cooked rations, which, with eight days’ fresh beef upon the hoof will make ten days’ full rations. Two days’ only are put in the haversack, for the reason that the weight is more easily carried upon the back.
The board also thought that if two pack-mules with pack-saddles were furnished to each regiment, a sufficient number of camp-kettles might be carried, with rations of rice, beans, and desiccated vegetables sufficient to cook the fresh beef properly, and furnish the necessary quantity of soup upon all occasions, and make the one hundred biscuits last ten days instead of eight, as before stated.
The question creating most embarrassment in the minds of the board was how to provide for line officers who have no knapsacks, but it is considered that all difficulties can be obviated upon ordinary marches if each line officer is required to employ the servant for which he is paid. The officer himself can carry his blanket and two days’ rations, and the servant the balance; it being understood that his necessary baggage and mess-chest should be carried in a reserve column of transportation.
The foregoing is stated to show what can be carried under the most favorable circumstances, but considering the marching rate, the state of the roads, and the fact that three days’ rations has heretofore been the maximum amount, the board recommend as follows:
1. That all extra clothing, except a change of underclothing, be stored.
2. That five days’ rations of bread and small-stores be placed in the knapsack.
3. Three days’ cooked rations in the haversack, and five days’ fresh beef upon the hoof
4. Two mules per regiment to carry camp-kettles, rice, beans, &c.

Each soldier will carry—
Pounds.
Haversack 5¾
Knapsack 6
Blanket 5¼
Clothing . . . . 2
Total 19

Making 13¼ pounds in the knapsacks, being 24 pounds less than the weight usually carried by soldiers in this army in their knapsacks.

RECAPITULATION.
Days.
Maximum, with 2 mules’ transportation 12
Maximum without transportation 10
Mean 8

There's some more here!

CAMP NEAR FALMOUTH, VA., May 29, 1863.
Brig. Gen. M. C. MEIGS,
Quartermaster- General U. S. Army, Washington, D. C:

GENERAL: I have the honor to acknowledge the receipt of your communication of the 12th instant, requesting a report of the operations of the quartermaster’s department during the late campaign, and answers to certain inquiries.
I have required a report from each of the chief quartermasters of the different corps. They are herewith inclosed, marked from A to II. I beg you will give these reports a close perusal, because they are very full, and contain much valuable information for our department touching the movement of troops in the field. In submitting these papers, I shall deem it necessary to give my views very briefly.
A copy of a report prepared by General Pleasonton, now commanding the Cavalry Corps, showing its present condition, is submitted, marked I.* Also, a copy of the proceedings of the board detailed to examine how many days rations, clothing, & c., can be carried by troops on their persons on a march without wagons, herewith, marked K.
I will reply to your questions as follows:
Question 1. “The orders for the outfit and equipment.”
Answer. It was ordered mainly that each man should carry eight days short rations of provisions, one change of underclothing, and 60 rounds of ammunition on his person. He was also to carry his blanket or overcoat, his musket, and accouterments. In many instances both blanket and overcoat were carried, but it was not the intention.
Question 2. “The details of the outfit and equipment; the burden carried by each soldier, and its weight,” & c.
Answer. The total weight carried by each soldier was 45 pounds. It consisted of his knapsack, haversack, subsistence, and change of underclothing, overcoat or blanket, arms and accouterments, and one piece of shelter-tent. Eight days short rations were carried on the person, stowed as follows: Five days in the knapsack, and three days in the haversack; 40 rounds of ammunition were carried in the cartridge-boxes, and 20 rounds in the pockets of the man’s clothing. The total weight carried by the men, as reported by the different corps quartermasters, varies somewhat. The amount stated by me, however, is the correct figure.
Question 3. “Same as to officers.”
Answer. Each officer was responsible for his own outfit. It was to be carried by himself or servant. In some instances a few pack animals were used.
Question 4. “What tents were taken with the troops, and how transported?”
Answer. Shelter-tents were taken by the troops, each soldier carrying a piece.
Question 5. “What wagons, if any, accompanied the marching columns?”
Answer. No wagons followed the main column over the river at first. Some ammunition wagons were brought up, but not necessarily.
Question 6. “What pack trains?”
Answer. Pack-mules were used to transport reserve ammunition, and to pack up other supplies from the wagon parks.
Question 7. “The details of loading of each wagon and pack-mule”
Answer. A 6-mule wagon will carry 1,400 short rations of provisions, bread, coffee, sugar, salt, and soap, and eight days rations of short forage for the 6 mules, or 25 boxes small-arms ammunition. A good pack-mule could carry 2 boxes small-arms ammunition, and six days oats for himself, or an equivalent in weight of subsistence for men.
Question 8. “The organization of the teams.”
Answer. The teams and pack trains were distributed to the corps and other commanders on the basis established in my circular of March 10, 1863, herewith, marked L. It was ordered that mules for packing should be drawn from the ammunition and supply trains when necessary, but never more than 2 from any one team, thus leaving 4 mules for the wagon. By this arrangement, all the wagons could move forward when required, with moderate loads, while pack trains were being used.
Question 9. “The actual supply of ammunition and of rations accompanying the marching column.”
Answer. The troops carried eight days supply of provisions and 60 rounds of ammunition on their persons.
Question 10. “The supplies moved from Falmouth and following in rear of the army.”
Answer. On the wagons and pack-mules there must have been at least six or eight days more, all loaded and ready for the road. There was a plentiful supply of ammunition.
Question 11. “What did the troops carry through the campaign? Did they throw away overcoats, & c.?”
Answer. The troops carried through the campaign only those things most necessary for their constant use. On the second and third days many abandoned overcoats and blankets, as the weather was warm. Very many abandoned their knapsacks on going into action. The impulse with the soldiers to throw off all impediments, under such circumstances, is almost irresistible. With proper discipline, soldiers can be made to take care of their knapsacks and all other property put on their persons. On the late campaign a blanket should have been taken, but no overcoat. Both weigh a man down too heavily, and are not necessary in moderate weather. When men become heated or fatigued they will throw away such articles as are not imperatively needed. On short campaigns, or marches of four or five days without wagons, I would not take a knapsack at all, but would put the rations in the haversacks, and other things in the blanket, well folded, and thrown over the right shoulder, and looped under the left arm. But if knapsacks containing rations, & c., are worn by troops, they should be made to fight with them on; or, if that be deemed unadvisable, great care should be taken, before putting them in action, to have the knapsacks stowed away properly in the rear. On the late campaign, the army abandoned in battle about 25 per cent. of the whole number. With due precaution, these might, of course, have been saved. Along the roads and at camp-grounds I saw many parts of blankets, overcoats, & c., discarded. The accompanying reports will show quite clearly how much clothing was used up and abandoned in the campaign. The army was perfectly equipped at the commencement in every particular, so far as concerned our department. The issues made immediately after were to supply deficiencies, which arose in the interim. On future marches this army will correct the errors referred to.
Question. 12. “Have the men shown ability to carry those supplies without injury to health?”
Answer. The troops exhibited adequate strength to carry all the articles composing their outfit. Marches were never made with more cheerfulness, vigor, and regularity. The army could have marched the eight days without embarrassment, so far as supplies were concerned. While at Chancellorsville, no difficulty was experienced by our department in bringing forward all that was required. At no time aid I feel that there could be any failure to supply the army on either side of the Rappahannock.
Question 13. “What are the daily marches? A map or itinerary of each brigade’s or division’s march would be of value.”
Answer. A sketch is inclosed, marked IV,* showing the theater of the operations. The system of transportation adopted with this army works admirably, and experience and observation have suggested no further change. I am satisfied with it, and I believe this army is. The number of ambulances is now reduced to two to each regiment. The pack-mule system cannot be relied on for long marches with heavy columns. I shall have few hereafter, and intend to make them auxiliary simply to wagons, for short distances over rough country, where there are few and bad roads. The new standard of means of transportation for the cavalry is as follows:
Four wagons to each 1,000 men for small-arm ammunition.
One wagon for hospital supplies for each regiment.
One wagon for regimental headquarters.
One wagon and two pack-mules for each company.
I do not consider that this scale can be amended. I desire to state that all the animals belonging to our department are now in splendid condition, except the pack-mules, most of which are in good order as to flesh, but have been galled badly in packing.
I wish to call your attention to General Pleasonton’s report, in order that you may perfectly understand why I call for so many cavalry horses. The report explains the case briefly. You will recollect that just before our late cavalry raid there was a review of the whole corps by His Excellency the President of the United States. It was admitted on all sides that the corps was then in fine condition. There were present for duty at that time certainly at least 10,000 horses. To-day not more than 5,000 serviceable ones can be mustered in the corps. There has been no complaint of extraordinary marches or want of forage. What, then, has temporarily destroyed these horses? If we inflicted a proportionate loss on the enemy, he has suffered terribly.
There was too much weight carried on the cavalry horses after leaving the Rappahannock; they were not unsaddled, perhaps, and groomed at intervals, to say nothing of irregular watering and feeding, & c.
I am, very respectfully, your most obedient servant,
RUFUS INGALLS,
Brig Gen., and Chief Quartermaster Army of the Potom

Time to get cooking, measuring and substituting to see how many bricks of delicious hardtack i can fit in my beloved blanket.