---
title: "Monte Carlo Retirement Simulation Inputs Reference"
description: "Reference table of standard inputs used in Monte Carlo retirement simulations including return assumptions, volatility, and inflation rates by asset class."
canonical: https://www.getswoopr.com/tables/portfolio/monte-carlo-retirement-inputs-reference/
source: "Swoopr Investment: https://www.getswoopr.com"
---

## Direct Answer



> Monte Carlo simulations model thousands of possible market paths to estimate retirement success probabilities. Standard inputs use long-term historical averages: 10.5% nominal (7% real) for U.S. stocks, 5% nominal (2% real) for bonds, 3% inflation, with standard deviations of 15-17% for stocks and 6-8% for bonds.







# Monte Carlo Retirement Simulation Inputs Reference



By [Swoopr Editorial Team](https://www.getswoopr.com/authors/swoopr-editorial-team/) · Published September 17, 2026 · *AI-assisted research, editorially reviewed.*





## Standard Monte Carlo Capital Market Assumptions



| Asset Class | Expected Annual Return (Nominal) | Expected Annual Return (Real) | Standard Deviation | Typical Correlation to Stocks |
| --- | --- | --- | --- | --- |
| U.S. Large Cap Stocks | 10.5% | 7.0% | 15-17% | 1.00 |
| U.S. Small Cap Stocks | 11.5% | 8.0% | 20-22% | 0.80 |
| International Dev. Stocks | 9.0% | 5.5% | 17-19% | 0.75 |
| Emerging Market Stocks | 11.0% | 7.5% | 23-26% | 0.65 |
| U.S. Aggregate Bonds | 4.5% | 1.5% | 5-7% | -0.10 |
| 10-Yr Treasuries | 4.0% | 1.0% | 7-9% | -0.15 |
| TIPS (10-Yr) | 2.0% | 0.5% | 6-8% | -0.05 |
| Cash/Money Market | 3.5% | 0.5% | 0.5-1% | 0.05 |
| U.S. Inflation (CPI) | N/A | N/A | 1.5% | N/A |



Source: Capital Market Assumptions from [BlackRock](https://www.blackrock.com/), [Vanguard](https://investor.vanguard.com/), [JP Morgan](https://am.jpmorgan.com/) (2025-2026 editions). Last verified: September 2026.







## Frequently Asked Questions


### What is a Monte Carlo retirement simulation?

A computational method that runs thousands of randomized sequences of market returns to estimate the probability of a retirement portfolio lasting a specified number of years. It accounts for the sequence-of-returns risk that simple average-return calculations miss.


### What inputs matter most in a Monte Carlo simulation?

Expected returns and their standard deviations for each asset class, correlation between asset classes, inflation rate, withdrawal rate, time horizon, and starting balance. Small changes to expected stock returns have the largest impact on outcomes due to stocks' high weight and long compounding horizon.


### What success rate should I target in Monte Carlo simulations?

Most financial planners target 85-95% success probability. A 90% success rate means the simulated portfolio survived 90% of the 10,000 scenarios tested. Targeting 100% is overly conservative and requires an extremely low withdrawal rate.







## Cite This Page



If you reference this table in your own work, use the following citation format and add the date you accessed it:



> Swoopr Editorial Team. (2026). *Monte Carlo Retirement Simulation Inputs Reference*. Swoopr Investment. [https://www.getswoopr.com/tables/portfolio/monte-carlo-retirement-inputs-reference/](https://www.getswoopr.com/tables/portfolio/monte-carlo-retirement-inputs-reference/)



Check the figures against the primary sources listed under References before you rely on or republish them; the series they come from are revised.







## References



- [BlackRock: Capital Market Assumptions](https://www.blackrock.com/)
- [Vanguard: Retirement Planning Resources](https://investor.vanguard.com/)
- [JP Morgan Asset Management: Long-Term Capital Market Assumptions](https://am.jpmorgan.com/)