MCPCalc

DnD Dice Calculator

Roll dice totals, expected values, and target success odds for tabletop RPGs.

Scratchpad (not saved)

Add or subtract to the roll total

Leave 0 to skip success odds

What This Calculator Does

Roll dice totals, expected values, and target success odds for tabletop RPGs.

It combines Number of Dice, Die Type, Modifier, Target Number to estimate Expected Total, Minimum Total, Maximum Total.

Formula & Method

Expected roll total is E=NumDice\cdot\frac{s+1}{2}+Modifier for d_s. Range is [NumDice+Modifier,\;NumDice\cdot s+Modifier]. Target success uses exact summed-outcome distribution over all s^{NumDice} outcomes.

Notation used in the formulas: R = Expected Total; x_{1} = Number of Dice; x_{2} = Die Type; x_{3} = Modifier; x_{4} = Target Number.

Method summary: inputs are normalized to consistent units, core equations are evaluated, then secondary values are derived and rounded for display.

Use this calculator for quick scenario analysis. Start with baseline values, change one driver at a time, and compare how sensitive the results are to each input shown above.

Inputs Used

  • Number of Dice: Used directly in the calculation.
  • Die Type: Used directly in the calculation.
  • Modifier: Add or subtract to the roll total
  • Target Number: Leave 0 to skip success odds

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