Well – obviously he/she is not unladen if she/he has a backpack full of loot and rations unless he/she/it is very strong.
Few player characters always want to use the toughest armor they can find and it can be tough to figure out how that affects the speed that they can walk, can they even run, how about jumping over that ravine. Can they even move at all. How much do their skills suffer. What if they are wearied from Fatigue. What if they drop the leg braces and the backpack. What if they enter jungles of Monster Island. How about if they drop the armor altogether and keep just the weapons or some of them. What if they roll a critical on their athletics while doing the move.
Now there is a version of FES calculator that combines the RAW rules, Monster island jungle rules and all the movement related rules from the RAW to calculate all of this.
It makes it much easier to see all the effects that encumbrance, terrain and fatigue make. The aim here is to make movement speed also count – when escaping One-Eye the Carnosaur you do not have to be the fastest but faster than 2-4 of the slowest ones. You should also be make the hard decisions what to drop to escape easily from game mechanics point of view.
The encumbrance and fatigue can make drastic changes to the speed and skills. This tool aims to help the use of them to support the game session.
The calculator handles the movement rates from 3-8, armo penalties from 0-29, athletics skills from 0-120 and swimming skills from 0-80. Why these limits – well it turned out to be way more convenient to calculate and test the movement rates outside Excel in Python and these are the limits I chose for a starter. So there is a data sheet of 250.000+ lines generated with excel and this makes the Excel a medium sized beast for the computer. Might work on that later… The version probably requires a recent version of Excel as it uses some formulas that might only exist in Excel.
There are few things one needs to input
- Strength
- Constitution
- Dexterity
- Intelligence
- Select current fatigue level from a list
- Athletics skill
- Swimming sill
- Select whether armor is worn or not
- Select all the equipment one wants to either wear or carry from the list

After these FES carries out the calculations and creates a table for results

The colors yellow and various shades of red indicate something to note about the effects.
There are four columns for different scenarios: Fully loaded, Without Backpack and the similar ones for Fully loaded in jungle and without backpack in jungle.
After filling out the FES – you can save a copy for each player character and start using it. During the scenario – when fatigue, speed or encumbrance matter – change the fatigue level and select whether you wear armor or not. If you are not satisfied with the numbers – drop or add equipment by adding or changing the item count number of each individual line you want or need to change in the equipment list. Only the orange fields are meant to be changed.
This will evolve with feedback plus there are already things in the roadmap for supporting combat styles etc on this one.
If you find mistakes or improvement needs please do not hesitate to contact.
Here is another example:

The Fatigue, Encumbrance and Speed calculator exists here. It replaces the old Encumbrance Calculator and Monster Island Fatigue Calculator. Many other charts for Mythras exist here.