IGP-M acumulado
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The IGP-M cumulative calculator is a tool to determine the total variation of the General Price Index - Market (IGP-M) over a specific period. It is particularly useful for contractual adjustments, monetary correction of debts, or analyzing accumulated inflation in real estate operations.
The formula used is ∏(1 + i/100) − 1, where each 'i' represents the monthly percentage variation of the IGP-M. The product (∏) multiplies all monthly factors cumulatively, and the final result is converted to a percentage. For example, with three months of 1%, 2%, and 3% variations, the calculation would be (1.01 × 1.02 × 1.03) − 1 = 6.16%.
Use this calculator when you need a cumulative average instead of an arithmetic mean. It is common in long-term contracts, such as leases or loans, where compound variations have an impact. Avoid using it to compare periods of different durations without proportional adjustments.
Be careful when entering monthly values: they must be exact, including decimal places, and the selected period should be continuous. The calculator does not automatically adjust for non-business dates or official corrections, so check official IGP-M sources to ensure data accuracy.
Frequently asked questions
How does the calculator's formula work?
The calculator multiplies all monthly factors (1 + variation in decimal) and subtracts 1 from the final result. This reflects the compounded effect of accumulated variations.
Why use the product (∏) instead of summing the variations?
The product reflects the compounded effect of monthly variations, while a simple sum would underestimate the total variation.
What is the difference between cumulative IGP-M and annual IGP-M?
Annual IGP-M is a simple average of the period, while the cumulative version considers the compounded effect of each month.
Can I use this calculator for non-consecutive periods?
No. The calculation requires a continuous sequence of months. For interrupted periods, calculate each segment separately.
How accurate is the calculator's result?
Accuracy depends on the input values. Use the official IGP-M indices published by FGV to ensure reliability.