Jim's Holy Roller

Roll any number of dice combinations you can think of, then simulate thousands of rolls to see the real odds behind your dice. No ads, no accounts, works fully offline.

Jim's Holy Roller is a fast, no-nonsense dice roller for tabletop RPGs — and a probability calculator hiding inside a dice app.

Type a dice expression, tap Roll, and get your result. Want to know how likely that result actually is? Tap Simulate to roll the same expression thousands of times and watch the outcomes fill in a live histogram, complete with percentages and the top 5 most common totals.

SUPPORTED DICE NOTATION • Standard rolls — 1d20, 2d6, 3d8, 1d100 • Modifiers — 2d6+3, 1d20-1 • Keep and drop — 4d6dl1 (drop lowest), 2d20kh1 (keep highest), plus dh/kl • Exploding dice — 3d6! (max rolls roll again) • Advantage and disadvantage — type "adv" or "dis" for D&D-style d20 rolls

SEE THE PROBABILITIES Rolling once tells you what you got. Simulating tells you what to expect. Run hundreds or thousands of trials and see the full distribution as a bar chart — perfect for comparing builds, weighing a risky attack, or just settling an argument about whether 4d6 drop lowest is really that generous.

Whether you're rolling for damage or geeking out over the math behind your dice, Jim's Holy Roller gives you both the roll and the reason.

Privacy: No account, no ads, no tracking. Jim's Holy Roller uses anonymous analytics only to understand general usage and improve the app — it never sells your data or tracks you across other apps.