Derived Values
Every number computed from another number is a number that goes stale. The case for printing the result, not the formula.
01The Staleness Problem
A derived value is any number on the sheet that is calculated from something else: initiative from Dexterity, encumbrance capacity from Strength, saving throws from a base score, hit points from Constitution and level. The formula lives in the rulebook; the sheet is supposed to carry the answer.
What to pull from the prose
- 01Derived value — any stat calculated from one or more other stats; initiative, encumbrance limit, saving throw modifiers are stock examples
- 02The formula vs. result distinction — formulas belong in rulebooks; results belong on sheets
- 03The staleness failure mode — a derived value updated at the source but not on the sheet silently corrupts play
- 04The transparency counter-argument — useful for understanding, poor justification for live-table layout
Except it rarely does. Sheets printed with formulas — Saving Throw = 12 − Level, Initiative = DEX modifier + Proficiency — hand the arithmetic back to the player every time the underlying stat changes. Level up, gain a magic item, take a curse: every connected number must be re-derived by hand. Miss one and the sheet carries a quiet error that might survive for months of sessions.
The alternative is simple: print the result. One box, one number, updated the moment the source changes and not touched again until it does. Defensive bonus is 14. Not 10 + Armor + DEX mod. Just 14.
This is not laziness. It is the sheet as an interface doing its job: the player should be reaching for a number under pressure, not running a calculation. Every formula that remains visible at the table is a tax on attention paid at exactly the wrong moment.
Transparency belongs in the explanation of the rule, not inside the box a player reads during the third combat round.
The counter-argument is transparency — if players can see the derivation, they understand the system and can catch errors. True, but that argument favors the rulebook, not the character sheet. The rulebook is read once; the sheet is consulted hundreds of times. Transparency belongs in the explanation of the rule, not inside the box a player reads during the third combat round.
Some designs split the difference: a small formula printed as a reminder beneath a large write-in box for the result. That is a reasonable compromise, provided the result box is unmistakably the primary element. When the formula is the same size as the answer, the layout has misjudged which one the table actually uses.
Derived values are promises about freshness. Design the sheet to keep them.