Weight

In Fallout 3, weight refers to the measure of how much an item weighs in pounds, and how many total pounds the player is carrying. Most items have a weight rating. The total weight the player is carrying is the sum of the weight ratings of all items carried, held, and worn. Carrying too much weight can affect a player's movement rate and movement abilities.

The Weight Limit (Carry Weight)
The amount of weight the player is carrying and the total weight limit (carry weight) is shown in the Pip-Boy along the top of the display while the ITEMS button is selected. The weight values show up as a fraction to the right of the Wg label, with the total amount of weight carried coming first, and the weight limit coming after the /.

The weight limit is not a hard-limit that prevents you from carrying more items. The weight limit is a threshold that if surpassed, limits player movement until the weight carried matches or drops below the threshold. Being exactly at the weight limit will not affect player movement; the player is only penalized for going over the limit.

Weight And Movement
If a player is over the weight limit, their movement is limited to walking speed and the player is unable to jump. Normal walking speed is not reduced for a player over the limit, so toggling the movement rate from run to walk has no noticeable effect.

Players over the weight limit also cannot use the fast travel feature, but being over the limit does not affect sneaking, combat, or any other normal gameplay functionality.

Managing Weight
Most items have a weight rating listed in their description. Any item with a weight rating of - - has no weight, and therefore may be carried in any quantity without concern that it will contribute to the player being over the weight limit. Most ammunition, quest items, and chems have no weight rating.

The game moves very slow if you are over the weight limit, so staying under it is of top concern. Here are some tips for staying under the limit:

Store It!
Use the many storage options in your house at Megaton or Tenpenny Tower to store items you wish to save for later in the game so you don't have to lug them around. If you don't yet have a house, explore the map to find a container such as a locker, box, or Nuka Cola machine to use for temporary storage until you get your house. There is also a Mailbox in Springvale that is near the spawn point, and can hold an infinite amount of storage goods, is able to be "decorated", and doesn't have the multiple load screens like the two houses you can own.

Plan It!
Plan your inventory before setting out. Travel light and take only what you expect to normally use. Check your total item weight before leaving for some action and become familiar with how much you normally carry, so that if you are over your normal rating you are alerted to the possibility you are carrying something you don't need. Consider these tips:
 * Minor healing items such as food and animal meat are plentiful enough during most encounters; supply yourself with only healing items that have no weight rating and expect to supplement them with items you find in the field.
 * Unless you are an explosives fool, only carry a few grenades and mines; the times you actually need them are rare, and there are plenty to pick up in many encounters.

Drop It!
It is better for your sanity and game enjoyment to drop heavy items to ensure fast movement rather than poke along at a snail's pace. Here are some tips on how to drop items efficiently:
 * Upon zoning into a new area, look for a container near the entrance that you can use to store bulky items you don't want to lose. Items stored in a container will usually remain there unmolested so you can return later and re-acquire them. When you've cleared the place out, it will be easy to grab a handful of stuff, zone out and fast travel to a merchant to sell it, then repeat until you've got it all.
 * Some items are worth very little yet have a lot of weight, such as fission batteries, or heavily damaged big guns or armor; consider dropping them even if you may not be able to retrieve them later.
 * If you plan on traveling by foot and not using fast travel, Dropping an object and pressing 'Z' on PC or clicking right thumbstick / analog stick down on the 360 / PS3 will allow you carry the object without it being in your inventory. While this allows you to move at full speed if you would otherwise be over the weight limit, it effectively prevents you from engaging in combat by keeping the object directly in front of the player, blocking any bullets or other attacks.

Note: Items dropped on the ground in the Capital Wasteland have a chance of being picked up by NPCs while you're away.

Sell It!
If you have no reasonable way to store items for later pickup while out in the field, and you don't want to drop things, fast travel to merchants to dump inventory. If you're in the Capital Wasteland, move near a discovered location on the world map and make note of your position before you leave so you can return to the same spot. If you're in a zoned area, about the time you get full, find the nearest exit to the Capital Wasteland and do the same. Remember you can pop out to balconies or rooftops and still fast travel -- you don't always have to go out the way you came in.

Merchants have limited funds to pay for the items you are selling, and some are not available at certain times of the day. Underworld, Big Town, Megaton (Gob and Doc Church), and the traveling merchants are good resources for late-night sell-fests. Sell the heavier items first in case the merchant doesn't have enough to pay for everything you want to sell.

Repair It!
The game rewards a high repair skill. Encounter areas often have multiple enemies that are similar in kind, and which will carry similar weapons. When you reach the weight limit in the field, boost your repair skill to its max with clothing or drugs and repair items using other similar items. With a decent repair skill, you may find yourself transitioning from 3 sets of Raider Painspike Armor worth an average of 20 caps each and weighing a total of 45 pounds, to a single set of Painspike worth 100 caps and weighing 15 pounds.

Boost It!
Ant Nectar, any alcohol, and Buffout all raise your strength skill for a limited amount of time. You can use these drugs to temporarily increase the amount you can carry and maintain a fast movement rate. Fortunately, if you are under the effects of these drugs, you can still fast travel even if the effect would have worn off during normal travel of that distance. In that case, the effects will wear off once you emerge from fast travel mode.

The various types of Power Armor also boost your strength and increase carrying capacity, but require special training to use.