Step 1: Enter your maintenance chest's total storage space (e.g., 50,000 for a full gold vault). To get this, you can count each block and multiply that by how much each block can hold, OR, you can just count the Total Rows x Total Columns x Stack Size (20 x 5 x 500) for a gold vault

Step 2: Enter the stack size into the input. The stack size is seen when you put the resource in, you will see it be like 200, 300, or 500 per stack. That is the number to enter.

Step 3: In-game, open your base maintenance panel. Enter each resource's daily upkeep value (the number shown next to each resource — see example image).

In that image, the 706, would be the number you would put with the name Redwood.
Once you fill in the first resource, click the "+Add Resource", and repeat with the next resources.

Step 4: Click Calculate to see your maximum maintenance time and optimal stack allocation.

Note: Results show whole hours (like the game) and use only full stacks.