Force Index
Calculate the Force Index for a given price series.
The Force Index is an indicator that measures the strength behind price movements.
The formula is as follows:
\[\text{Raw Force Index} = (\text{Close} - \operatorname{Close}(1)) \cdot \text{Volume}\] \[\text{Force Index} = \operatorname{EMA}(\text{Raw Force Index},\; \text{window})\]Also known as: FI, Elder’s Force Index.
Force Index in Python
get_force_index is part of the Technicals module of the open-source Finance Toolkit. Install it with:
pip install financetoolkit -U
Then call get_force_index as shown below.
from financetoolkit import Toolkit
toolkit = Toolkit(tickers=["AAPL", "MSFT"])
toolkit.technicals.get_force_index()
Which returns:
| Date | AAPL | MSFT | Benchmark |
|---|---|---|---|
| 2026-06-18 | 1.5469e+09 | 2.64103e+08 | 5.23308e+09 |
| 2026-06-22 | -7.46954e+08 | -6.39817e+09 | -2.13467e+09 |
| 2026-06-23 | -2.04451e+09 | 3.52532e+09 | -1.02007e+10 |
| 2026-06-24 | -9.23144e+08 | -4.57591e+09 | -3.22888e+08 |
| 2026-06-25 | -1.46857e+10 | -7.31369e+09 | 1.01111e+09 |
| 2026-06-26 | 8.76398e+09 | 1.47121e+10 | -4.94319e+09 |
| 2026-06-29 | -2.04817e+09 | -3.2984e+09 | 1.1285e+10 |
| 2026-06-30 | 7.61233e+09 | 3.37872e+09 | 5.23673e+09 |
| 2026-07-01 | 5.00175e+09 | 8.72373e+09 | -9.03283e+08 |
| 2026-07-02 | 1.4666e+10 | 4.77999e+09 | -8.48204e+08 |
Parameters
get_force_index accepts the following parameters:
- period (str, optional): The time period to consider for historical data. Can be “daily”, “weekly”, “quarterly”, or “yearly”. Defaults to “daily”.
- close_column (str, optional): The column in the historical data that represents the closing prices. Defaults to “Adj Close”.
- window (int, optional): The number of periods for calculating the Force Index. Defaults to 14.
- rounding (int | None, optional): The number of decimals to round the results to. Defaults to 4.
- growth (bool, optional): Whether to calculate the growth of the indicator values. Defaults to False.
- lag (int | list[int], optional): The lag to use for the growth calculation.
- standardize (bool, optional): Whether to standardize (Z-Score) the result. When combined with growth=True, standardizes the growth values instead of the raw values. Defaults to False. Defaults to 1.