Py-Vollib

1.0.7 verified Fri May 01 auth: no python deprecated

Deprecated transition package for vollib, a Python library for pricing and calculating option implied volatility using Black-Scholes, Black (1976), and Garman-Kohlhagen models. Version 1.0.7 is the final release; users should install 'vollib' (the canonical package) instead. py_vollib is published as a stub that depends on vollib and provides deprecated compatibility imports. Release cadence is low; actively maintained on GitHub under the vollib organization.

pip install vollib

Common errors

error ModuleNotFoundError: No module named 'py_vollib' ↓

cause Cannot import py_vollib after installing py-vollib (some environments break due to package name mismatch).

fix

Install the canonical package: pip install vollib, then import vollib.

error ImportError: cannot import name 'black_scholes' from 'py_vollib' ↓

cause py_vollib compatibility shim missing or outdated.

fix

Switch to vollib: from vollib.black_scholes import black_scholes

Warnings

deprecated py-vollib is deprecated. The canonical package is 'vollib'. Install and import 'vollib' instead. ↓

fix pip uninstall py-vollib && pip install vollib, then change imports from py_vollib to vollib.

breaking Stale dependency path: py_vollib==1.0.7 pins an old vollib version. Avoid installing py_vollib directly. ↓

fix Do not install py-vollib; use vollib directly.

gotcha Flag argument 'c'/'p' is case-sensitive; lower case only. Also, all numeric inputs must be floats (ints may cause type errors in some versions). ↓

fix Always use 'c' or 'p' (lowercase) and pass floats: e.g., S=100.0, not 100.

Install

pip install py-vollib

Imports

black_scholes
wrong
```
from py_vollib.black_scholes import black_scholes
```
correct
```
from vollib.black_scholes import black_scholes
```
py_vollib.* imports work via compatibility shim but are deprecated. Use vollib.* instead.

black

wrong

from py_vollib.black import black

correct

from vollib.black import black

Same as above; prefer canonical vollib.

implied_volatility

from vollib.black_scholes import implied_volatility

Quickstart

Basic usage of vollib for Black-Scholes pricing and implied volatility calculation.

from vollib.black_scholes import black_scholes, implied_volatility

# Option parameters
S = 100.0   # underlying asset price
K = 105.0   # strike price
t = 0.5     # time to expiration in years
r = 0.02    # risk-free rate
sigma = 0.2 # implied volatility
flag = 'c'  # 'c' for call, 'p' for put

# Price using Black-Scholes
price = black_scholes(flag, S, K, t, r, sigma)
print(f"Option price: {price:.4f}")

# Implied volatility from observed price
observed_price = 5.0
iv = implied_volatility(observed_price, S, K, t, r, flag)
print(f"Implied volatility: {iv:.4f}")