The most Encumbered member of the party determines the speed and stealth bonus. Equipped items & armor count for encumbrance. This assumes the following procedure.
Not Encumbered: +1 stealth, -1 to Encounter range.
Lightly Encumbered: No stealth bonus. No change to Encounter range.
Moderately Encumbered: -1 stealth, +1 to Encounter range.
Greatly Encumbered: -2 stealth, +2 to Encounter range. Lose first combat round.
Stow is the number of items you have instant, easy access to on your person. The number of stow items worth of load is equal to the first 4 + Dex modifier items on your equipment list. Weapons DO count for stow, but armor or worn objects do not. Trying to use or extract any item from your inventory that is not in your stow takes 1d4-1 combat rounds.
For example; a lvl 2 Rogue archer would want to keep her bow, dagger, quiver of arrows, and a set of caltrops ready at her hand; total of 6 load. To grab her healing potion, it would have to take her 1d4-1 combat rounds to dig it out; she'd probably want the fighter between her and the enemy while digging, or go without until combat is over.
Weapons- Use size of damage die for load. d4 dagger or blackjack is 1 load, d6 sword or bow is 2 load, d8 polearm or claymore is 3 load, etc.
Thrown Weapons- Bundles of 3 per damage die size. For example, throwing daggers, bolas, darts, and chakrams at 1d4 are 1 load for 3 throwing weapons. Bigger sizes use larger loads for 3 items; Javelins and large acid flasks at 1d6 are 2 load for 3 items, etc.
Ammunition- Bundled in units of 20 per weapon die size for load. Sling bullets are carried in a bag of 20 bullets for 1 load. Arrows carried in quiver of 20 for 2 load. Heavy crossbow for d8 and Gunpowder flask and lead purse for a d8 musket weight 3 load for 20 shots, etc.
Tools- Approximate the tool to a weapon, or how you would use it as an improvised weapon, and use that as the load. Trowels and chisels are 1 load, shovels and prybars for 2 load, pickaxe & sledgehammer are 3 load each, etc.
Treasure- Each bag of 100 coins of any denomination is 1 load. Gemstones do not count for encumbrance, as long as they are not unnecessarily huge. Treasure chests are at least 2 load for one of those small ones, otherwise are load of 3+ and require both hands or two people to carry.
Supply Items & Misc- Rations, torches, and door wedges are all stored in bundles of 3. Halflings and similar sized beings, alive or a corpse, are load of 3 with humans and similar being 6 load.