How Harshonomics Calculators Work
A transparent guide to the formulas, inputs, assumptions and limitations used across Harshonomics calculators.
Why Calculator Methodology Matters
Financial calculators can make complex calculations easier, but the result is only as useful as the formula, inputs and assumptions behind it.
Harshonomics aims to make its calculators practical and transparent by explaining what users need to enter, how the calculation works and what the resulting estimate means.
Different calculators use different mathematical methods. Therefore, the exact formula, assumptions and limitations can vary from one calculator to another.
How Our Calculators Are Developed
Define the Calculation
The first step is identifying the financial or mathematical problem the calculator is intended to solve and determining the required inputs and output.
Determine the Formula
The relevant mathematical or financial formula is identified based on the type of calculation being performed.
Set the Assumptions
Where a calculation requires assumptions, such as a rate, period, frequency or other variable, those assumptions are made visible to the user where appropriate.
Test the Results
Calculations are checked using different input combinations and expected mathematical relationships to identify obvious calculation or implementation errors.
What Your Calculator Inputs Mean
Most calculators require users to enter information such as an amount, rate, time period, frequency or other relevant variables.
Users should enter values carefully and use the units requested by the calculator. Incorrect, incomplete or unrealistic inputs can produce results that do not represent the user’s actual situation.
Common Financial Calculation Methods
Harshonomics calculators use the mathematical relationships appropriate to the calculation being performed. Some common examples include:
Simple Interest
SI = P × R × T
Where P is principal, R is the rate and T is the time period.Compound Growth
A = P × (1 + r/n)nt
A is the accumulated amount, P is principal, r is the annual rate, n is the number of compounding periods and t is time.Percentage Change
Percentage Change = (New Value − Original Value) ÷ Original Value × 100
Used to measure the percentage increase or decrease between two values.CAGR
CAGR = (Ending Value ÷ Beginning Value)1/n − 1
Used to calculate the annualized growth rate over a specified period.These are examples of commonly used formulas. Individual calculators may use additional formulas or calculation methods depending on their purpose.
Calculations Are Estimates, Not Guarantees
Financial calculators are designed to provide estimates based on the information entered by the user. A calculator cannot predict every future event or financial condition.
For example, investment and retirement calculations may use an assumed rate of return. The actual return of an investment can be different because markets and financial conditions change over time.
Similarly, loan and tax calculations may depend on rules, rates, charges, eligibility requirements or other factors that can change.
Why Your Result May Differ Slightly
Some calculators display rounded values for easier reading. The underlying calculation may involve more decimal places than are shown on screen.
Small differences can also occur when another calculator uses different rounding rules, compounding assumptions, payment timing or calculation conventions.
For important financial decisions, users should verify the relevant figures with the applicable institution, official source or qualified professional.
How We Handle Changes
Some financial calculations are based primarily on established mathematical formulas, while others depend on financial rules, rates, tax provisions or other information that can change over time.
When a calculator depends on information that can become outdated, the relevant assumptions and content should be reviewed and updated when necessary.
Each calculator page may also contain additional explanations, assumptions, examples and limitations specific to that calculation.
Types of Calculators on Harshonomics
The calculator collection may expand over time as new financial and utility tools are developed.
Important Limitations
Harshonomics calculators are provided for general educational and informational purposes. Results are estimates and should not be treated as personalised financial, investment, tax or legal advice.
Actual outcomes may differ because of changes in interest rates, investment returns, taxes, fees, inflation, market conditions, regulations and individual circumstances.
Before making an important financial decision, consider your personal circumstances and, where appropriate, consult a qualified professional.
Read the full Financial Disclaimer →