How does the purchasing power calculator work?

Enter an amount in rands, a start date, and an end date. The calculator estimates what that amount would need to be worth at the end date to keep pace with M3 money supply growth over the same period.

What does 'purchasing power decrease' mean?

This is the percentage by which your money's purchasing power has dropped relative to M3 money supply growth. For example, 15% decrease means your money would need 15% more rands to have the same purchasing power relative to the total money supply.

Reading time: 4 minutes · Published: Jun 2025

TL;DR: Use the calculator to see what any amount of rands would need to be worth today to keep pace with M3 money supply growth. Enter a start date, end date, and amount. The result shows the M3-adjusted value and your estimated loss in purchasing power.

How to Use the Purchasing Power Calculator

The purchasing power calculator is the core tool on this site. Here is exactly how to use it and what the results mean.

What the Calculator Does

The calculator takes an amount of South African rands from a past date and estimates what that amount would need to be worth at a future (or present) date to keep pace with the growth of M3 money supply. It answers the question: "If my money had grown at the same rate as the total money supply, how much would I have?"

Step-by-Step: Entering Your Data

Start date: Pick the date you originally had the money (e.g., when you saved it, or the start of a period you want to measure).
End date: Pick the date you want to compare against (usually today or the current month).
Amount (R): Enter the amount in rands. The default is R1,000 but you can enter any value.
Click Calculate to see the result.

After calculating, the results appear in a box below the form.

Understanding Your Results

The calculator shows four key numbers:

Adjusted amount: What your money would need to be worth to keep pace with M3 growth.
M3 growth over the period: The total percentage that M3 grew between the two dates.
Annualised M3 growth: The average yearly growth rate of M3 over the period.
Decrease in purchasing power: The percentage by which your money's purchasing power dropped relative to M3. This is the most important number - it shows how much you have been left behind.

Example: If you entered R10,000 from January 2020 to January 2025, and M3 grew 45% over that period, the calculator would show your R10,000 needs to be R14,500 to keep pace. Your purchasing power decrease would be approximately 31%.

When to Use the Comparison Tool

The calculator on the homepage answers: "How much should this amount be worth?" If you want to answer: "Did my specific salary or investment keep up?" - use the comparison tool instead. There you enter both a starting amount and an ending amount, and the tool tells you whether you kept pace with M3 or fell behind.

For a visual overview, visit the M3 vs CPI chart to see how money supply has grown relative to official inflation over time.