CompoundLab calculators are designed to show not only the final number, but also the assumptions behind it.
A financial calculator can look precise while still being misleading if the formula, timing assumptions, fees, inflation, or tax treatment are hidden. CompoundLab’s methodology pages explain how each calculator works so users can understand what is being modeled, what is being simplified, and what should not be treated as a prediction.
These tools are educational planning tools. They are not financial advice.
Methodology principles
1. Formula transparency
Each calculator should explain the core formula or simulation logic behind the result.
When a calculator uses a simplified model, that simplification should be stated clearly.
2. Assumption clarity
Important assumptions should be visible, including:
- return assumptions
- inflation assumptions
- contribution timing
- compounding frequency
- fee treatment
- tax treatment
- withdrawal timing
- mortgage rate assumptions
- rent growth assumptions
- property appreciation assumptions
3. Nominal vs. real value
Some calculators show nominal money and inflation-adjusted money.
Nominal money is the future amount before adjusting for inflation.
Real value estimates what that future amount may be worth in today’s purchasing power.
4. Scenario-based planning
CompoundLab does not try to predict the future.
The calculators are meant to help users compare scenarios and understand which assumptions drive the result.
5. Limitations are part of the output
A calculator should explain what it does not include.
Many real-world factors are difficult to model precisely, such as market volatility, tax law, personal risk tolerance, liquidity needs, maintenance surprises, refinancing, or behavioral decisions.