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 or via the MCP
Install the Finance Toolkit with:
pip install financetoolkit -U
Then call get_force_index as shown below.
from financetoolkit import Toolkit
toolkit = Toolkit(
tickers=["TLT"],
api_key="FINANCIAL_MODELING_PREP_KEY",
start_date="2021-01-01",
end_date="2025-12-31",
)
toolkit.technicals.get_force_index().tail(5)
Or, after setting up the Finance Toolkit MCP, ask:
How did the Force Index of the iShares 20+ Year Treasury Bond ETF (TLT), its price change times volume, move from 24 to 31 December 2025?
Which returns:
| Date | TLT | Benchmark |
|---|---|---|
| 2025-12-24 | 946514 | 8.27837e+07 |
| 2025-12-26 | -287501 | 7.05413e+07 |
| 2025-12-29 | 1.09756e+06 | 3.86575e+07 |
| 2025-12-30 | 223430 | 2.75431e+07 |
| 2025-12-31 | -3.35421e+06 | -2.98818e+07 |
Parameters
get_force_index accepts the following parameters.
| Parameter | Type | Description | Example |
|---|---|---|---|
period | str | The time period to consider for historical data. Can be “intraday”, “daily”, “weekly”, “monthly”, “quarterly” or “yearly”. Defaults to “daily”. | "weekly" |
close_column | str | The column in the historical data that represents the closing prices. Defaults to “Adj Close”. | "Close" |
window | int | The number of periods of the EMA that smooths the raw Force Index. Defaults to 13, Elder’s setting for the trend (2 is his setting for timing entries). | 20 |
rounding | int | None | The number of decimals to round the results to. Defaults to None, which uses the rounding of the Toolkit (4 unless set otherwise). | 2 |
growth | bool | Whether to calculate the growth of the indicator values. Defaults to False. | True |
lag | int | list[int] | The lag to use for the growth calculation. Defaults to 1. | 4 |
standardize | bool | Whether to standardize (Z-Score) the result. When combined with growth=True, standardizes the growth values instead of the raw values. Defaults to False. | True |