CPI — Swiss Consumer Price Index

The CPI class provides access to Swiss Consumer Price Index data and year-over-year inflation rates, sourced from the Swiss National Bank (monthly data, 1921+).

from swiss_finance import CPI

`CPI.get_current`

CPI.get_current(provider='snb_cpi') -> float

Get the latest Swiss CPI index value.

Returns: Latest CPI index value (December 2020 = 100).

Raises: SNBAPIError if the API call fails.

Example:

cpi = CPI.get_current()
print(f"Swiss CPI: {cpi:.2f}")
# Swiss CPI: 107.40

`CPI.get_historical`

CPI.get_historical(start=None, end=None, provider='snb_cpi') -> pd.DataFrame

Get historical Swiss CPI index values (monthly, 1921+).

Parameters:

Parameter	Type	Description
`start`	`str`	Start date `YYYY-MM` (optional)
`end`	`str`	End date `YYYY-MM` (optional)
`provider`	`str`	Data provider (default: `'snb_cpi'`)

Returns: DataFrame with DatetimeIndex and cpi column.

Raises: ValueError if start > end, SNBAPIError.

Example:

cpi = CPI.get_historical(start="2020-01")
print(cpi.head())

              cpi
date
2020-01-01    101.2
2020-02-01    101.5
2020-03-01    101.4
2020-04-01    100.9
2020-05-01    100.7

# Full history since 1921
cpi_all = CPI.get_historical()
print(f"Data from {cpi_all.index[0].year} to {cpi_all.index[-1].year}")
# Data from 1921 to 2025

cpi_all.plot(title="Swiss CPI (SNB, 1921+)")

`CPI.get_inflation_yoy`

CPI.get_inflation_yoy(start=None, end=None, provider='snb_cpi') -> pd.DataFrame

Get Swiss year-over-year inflation rate. Computed as (CPI_t / CPI_{t-12} - 1) * 100.

Parameters:

Parameter	Type	Description
`start`	`str`	Start date `YYYY-MM` (optional)
`end`	`str`	End date `YYYY-MM` (optional)
`provider`	`str`	Data provider (default: `'snb_cpi'`)

Returns: DataFrame with DatetimeIndex and inflation_yoy column (percentage).

Raises: ValueError if start > end, SNBAPIError.

Example:

inflation = CPI.get_inflation_yoy(start="2020-01")
print(inflation.tail(5))

              inflation_yoy
date
2025-08-01           1.30
2025-09-01           1.15
2025-10-01           1.08
2025-11-01           1.12
2025-12-01           1.10

# Latest value
latest = inflation.iloc[-1, 0]
print(f"Latest YoY inflation: {latest:.2f}%")
# Latest YoY inflation: 1.10%

# Peak inflation during 2022 energy crisis
peak = inflation.loc["2022-01":"2023-12"]["inflation_yoy"].max()
print(f"Peak inflation (2022–2023): {peak:.2f}%")
# Peak inflation (2022–2023): 3.50%

# Plot inflation alongside policy rate
import matplotlib.pyplot as plt
from swiss_finance import SNB

fig, ax = plt.subplots(figsize=(12, 5))
inflation = CPI.get_inflation_yoy(start="2015-01")
rates = SNB.get_historical_rates(start="2015-01")

inflation["inflation_yoy"].plot(ax=ax, label="CPI YoY %")
rates["rate"].plot(ax=ax, label="SNB Policy Rate %")
ax.axhline(0, color="black", linewidth=0.5)
ax.legend()
ax.set_title("Swiss Inflation vs SNB Policy Rate")
plt.tight_layout()
plt.show()

Data source

CPI data is sourced from the SNB data portal (data.snb.ch), cube plkopr. Index base: December 2020 = 100. Monthly frequency, available from 1921.