Drawing names from a hat, rolling dice, shuffling a playlist, assigning Secret Santa — randomness is fairness made visible, and a random number generator is the digital hat. The classic ask is a random integer between two bounds: pick a number from 1 to 100, roll a 20-sided die (1 to 20), choose a raffle winner from tickets 1 through 500. True randomness is surprisingly hard — computers use pseudorandom algorithms seeded by the clock or system entropy — but for games, giveaways, and sampling it is more than fair enough.

Statisticians use random numbers for sampling and simulations, teachers for picking students, and developers for everything from game loot to A/B test assignments. The one rule: define your bounds inclusively and clearly, since 'random number' without bounds is meaningless. This calculator scales a 0-to-1 random decimal into your range: generate a random decimal on paper or from another tool (say 0.637), type the range size (max − min + 1) in the Variable A box — for 1–100, that is 100 — and type the random decimal in the Variable B box (0.637). The Result box shows 63.7; drop the fraction and add your minimum (1) to get 64, your random pick. For a die roll 1–20, use range size 20 the same way.

With the pre-filled defaults — Variable A 10, Variable B 5 — the Random Number Generator Calculator returns Result 50.0000. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.