What Is an Expected Value of Investment Calculator?

An expected value of investment calculator converts a set of scenarios into a single probability-weighted number. You supply the amount invested and what you expect to receive in the best, base and worst cases, along with the probability of each. The tool multiplies every outcome by its likelihood, adds the results, and reports the average outcome if the same investment were repeated many times.

Expected value is the foundation of rational decision-making under uncertainty, and it exists precisely because the instinctive approach — focusing on the most likely outcome, or on the best case — produces systematically bad decisions. The tool also quantifies the shape of the distribution: how often the investment loses money, how large a typical loss is, and how widely the outcomes scatter around the average.

How It Works

Each outcome is multiplied by its probability and summed. In the default example, a $30,000 outcome at 20%, a $12,000 outcome at 60% and a zero outcome at 20% produce an expected value of $13,200 against a $10,000 investment — $3,200 of expected profit, or 32%. Probabilities that do not sum to exactly 100% are rescaled proportionally rather than rejected, and the result records that normalisation happened.

The risk statistics come from the same weights. The variance is the probability-weighted average of the squared deviations from the expected value, and its square root is the standard deviation, which has the same units as the outcomes themselves. Dividing that by the expected value gives a coefficient of variation for comparing bets of different sizes, and the loss probability is simply the combined weight of every scenario whose outcome is below the amount invested.

Conditional figures add the texture that a single average hides. The expected gain if things go well is the probability-weighted average of the profitable scenarios; the expected loss if things go badly is the same calculation for the losing scenarios. Together they describe the bet: how often you lose, how much you lose when you do, and how much you win when you don't.

Understanding Your Results

The primary card shows the expected value with the expected profit and return. The three statistics beside it give the probability of loss, the standard deviation and the expected loss conditional on losing. A positive expected value with a high loss probability describes a lottery-shaped bet — profitable on average, painful most of the time — which is a position-sizing problem as much as a valuation one.

The table lists each scenario with its probability, outcome, profit and probability-weighted contribution, so you can see exactly which scenario is driving the result. Summary Statistics adds the best and worst case profits, the probability of profit, the expected gain if the investment works and the coefficient of variation. The most useful stress test is to move probability between scenarios while holding the outcomes fixed: shifting ten points from the best case to the worst case is often enough to turn a comfortable expected value into a marginal one.