What is a Monte Carlo simulation for a portfolio?

It draws thousands of random return paths, consistent with assumptions about average return and volatility, and reports the spread of outcomes: for example the value the portfolio reaches in the best 5% and worst 5% of paths.

How is Monte Carlo different from a historical simulation?

A historical simulation replays the actual sequence of past returns from every possible start date. Monte Carlo generates new sequences, so it covers paths that never happened, but its results depend on the return model it assumes.

What does a “chance of success” percentage mean?

It is the share of simulated paths in which the plan meets its goal, usually not running out of money before a given age. It describes the model’s assumptions, not a probability that markets will behave that way.

Guide · checked November 2026

Best Monte Carlo portfolio simulators in 2026

A Monte Carlo simulation generates thousands of possible future paths for a portfolio and reports the range of outcomes, for example the 5th and 95th percentile of its value, or the share of paths in which a retirement plan does not run out of money. The tools below differ in the return model they use and in whether they focus on a portfolio or on a whole financial plan.

Published by MEDGE Capital, which is one of the tools listed. Details of the other tools come from their public pages, checked in November 2026, with a link to each source below. Prices are list prices for one user, before tax; check with the vendor before you buy. The order is not a ranking.

Tool	Simulation	Price
MEDGE Capital	10,000 paths with 5th to 95th percentile bands, fitted on the backtested portfolio, next to the backtest, attribution and regimes. The methodology page states the model’s limits, such as thin tails.	Free plan with Monte Carlo included. Essential €14.99, Plus €39.99, Pro €59.99, Advisor €159 a month; 7-day Plus trial
Portfolio Visualizer	Return models based on history, on forecast mean and volatility or on a chosen distribution; withdrawals as a fixed amount, a fixed percentage or by life expectancy.	Free plan (up to 15 assets, limited history); Basic $30 a month and Pro $55 a month, billed annually
ProjectionLab	A chance-of-success estimate with up to 2,000 trials, on historical or probabilistic data, inside a whole-life financial plan.	Basic free; Premium $129 a year; Pro $549 a year for advisors
Boldin	Monte Carlo over 1,000 scenarios in the PlannerPlus plan.	PlannerPlus $168 a year; 14-day trial
FIRECalc	Runs a plan through every starting year since 1871 by default; also offers a random-returns option set by mean and standard deviation.	See the site
Engaging Data FIRE calculator	A Monte Carlo mode for the years before retirement, with 10th–90th and 25th–75th percentile bands in real terms.	No price shown on the site

MEDGE CapitalOur tool

Portfolio analytics for self-directed investors and independent advisors.

Simulation: 10,000 paths with 5th to 95th percentile bands, fitted on the backtested portfolio, next to the backtest, attribution and regimes. The methodology page states the model’s limits, such as thin tails.
Price: Free plan with Monte Carlo included. Essential €14.99, Plus €39.99, Pro €59.99, Advisor €159 a month; 7-day Plus trial
Fits if: you want Monte Carlo on a portfolio you have already backtested.

Read the methodology

Portfolio Visualizer

Web-based backtesting and portfolio analysis tools.

Simulation: Return models based on history, on forecast mean and volatility or on a chosen distribution; withdrawals as a fixed amount, a fixed percentage or by life expectancy.
Price: Free plan (up to 15 assets, limited history); Basic $30 a month and Pro $55 a month, billed annually
Fits if: you want to compare withdrawal models for a retirement portfolio.

Source: Monte Carlo simulation · Pricing

ProjectionLab

Financial and retirement planning app.

Simulation: A chance-of-success estimate with up to 2,000 trials, on historical or probabilistic data, inside a whole-life financial plan.
Price: Basic free; Premium $129 a year; Pro $549 a year for advisors
Fits if: you want a full life plan with income, expenses and milestones, not only a portfolio.

Source: Pricing · Chance of success

Boldin

Retirement planning app.

Simulation: Monte Carlo over 1,000 scenarios in the PlannerPlus plan.
Price: PlannerPlus $168 a year; 14-day trial
Fits if: you are planning retirement income in the US and want a guided planner.

Source: Pricing

FIRECalc

Retirement calculator based on historical market cycles.

Simulation: Runs a plan through every starting year since 1871 by default; also offers a random-returns option set by mean and standard deviation.
Price: See the site
Fits if: you want to know how a withdrawal plan would have fared in every historical period.

Source: Home · Introduction

Engaging Data FIRE calculator

Free interactive data-visualization site.

Simulation: A Monte Carlo mode for the years before retirement, with 10th–90th and 25th–75th percentile bands in real terms.
Price: No price shown on the site
Fits if: you want a quick visual estimate of time to financial independence.

Source: FIRE calculator

Frequently asked questions

What is a Monte Carlo simulation for a portfolio?: It draws thousands of random return paths, consistent with assumptions about average return and volatility, and reports the spread of outcomes: for example the value the portfolio reaches in the best 5% and worst 5% of paths.
How is Monte Carlo different from a historical simulation?: A historical simulation replays the actual sequence of past returns from every possible start date. Monte Carlo generates new sequences, so it covers paths that never happened, but its results depend on the return model it assumes.
What does a “chance of success” percentage mean?: It is the share of simulated paths in which the plan meets its goal, usually not running out of money before a given age. It describes the model’s assumptions, not a probability that markets will behave that way.

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