mortgagepy

mortgagepy is a python library used to work out common mortgage calculations including captial repayments, total cost of ownership and single month interest.

NOTE: This repository is still in development and the primary purpose is to understand good python packaging practices.

Installation

To install mortgagepy use the following command:

pip install git+https://github.com/charlieb954/mortgagepy.git

Examples - mortgage

Create a mortgage object and use it to compare against other mortgages.

Initialise a mortgage object.

>>> from mortgagepy import CapitalRepaymentMortgage

>>> my_mortgage = CapitalRepaymentMortgage(
        property_value=280000, mortgage=210000, term_months=300, interest_rate=1.8
    )

Get a summary of the mortgage.

>>> my_mortgage.summarise(printed=True)

                                        Capital Repayment Mortgage Summary                                         
┏━━━━━━━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┓
┃             ┃             ┃             ┃ Monthly     ┃              ┃             ┃              ┃             ┃
┃ Property    ┃ Mortgage    ┃ Loan To     ┃ Repayment   ┃ Term         ┃ Interest    ┃ Interest     ┃ Total Cost  ┃
┃ Value (£)   ┃ (£)         ┃ Value (%)   ┃ (£)         ┃ (Months)     ┃ Rate (%)    ┃ Paid (£)     ┃ (£)         ┃
┣━━━━━━━━━━━━━╋━━━━━━━━━━━━━╋━━━━━━━━━━━━━╋━━━━━━━━━━━━━╋━━━━━━━━━━━━━━╋━━━━━━━━━━━━━╋━━━━━━━━━━━━━━╋━━━━━━━━━━━━━┫
┃ 280000.0    ┃ 210000.0    ┃ 75          ┃ 869.79      ┃ 300.0        ┃ 1.8         ┃ 50937.0      ┃ 260937.0    ┃
┗━━━━━━━━━━━━━┻━━━━━━━━━━━━━┻━━━━━━━━━━━━━┻━━━━━━━━━━━━━┻━━━━━━━━━━━━━━┻━━━━━━━━━━━━━┻━━━━━━━━━━━━━━┻━━━━━━━━━━━━━┛

Calculate overpayment impact of the mortgage.

>>> my_mortgage.overpayment_projection(monthly_overpayment=100)

{
    'time to repay (months)': 263,
    'time saved (months)': 37.0,
    'total interest paid (%)': 23811.59,
    'interest saved (£)': 3617.41
}

Access individual attributes such as monthly repayments or LTV.

>>> my_mortgage.monthly_repayment()

869.79

>>> my_mortgage.ltv()

75

Examples - calculator

Calculate the monthly repayment for a capital payment mortgage.

>>> from mortgagepy.calculator import monthly_capital_repayment
>>> monthly_capital_repayment(
        mortgage=130_500, interest_rate=6.89, mortgage_length_months=300
    )

913.21

Work out the total cost of a mortgage.

>>> from mortgagepy.calculator import total_cost_of_mortgage
>>> total_cost_of_mortgage(
        mortgage=130_500, interest_rate=6.89, mortgage_length_months=300
    )

273_963.0

Calculate repayments for an interest only mortgage.

>>> from mortgagepy.calculator import monthly_interest_only
>>> monthly_interest_only_repayment(
        mortgage=130_500, interest_rate=3.89
    )

423.04

Calculate the loan-to-value as a percentage given a deposit and property value.

>>> from mortgagepy.calculator import ltv
>>> ltv(
        property_value=200_000, deposit=50_000
    )

75

Calculate the monthly interest to be paid on a mortgage.

>>> from mortgagepy.calculator import monthly_interest
>>> monthly_interest(
        balance_at_previous_month=98_868.70, interest_rate=1.89, month=10, year=2023
    )

158.7

Calulate the time saved by overpaying on your mortgage.

>>> from mortgagepy.calculator import capital_overpayment
>>> capital_overpayment(
        mortgage=200000, interest_rate=3.5, mortgage_length_months=300, monthly_overpayment=100
    )

{
    'time to repay (months)": 262,
    'time saved (months)': 38,
    'total interest paid (£)': 87992.71
}

Examples - compare

Compare the cost of two interest rates for a capital repayment mortgage.

>>> from mortgagepy.compare import compare_capital_repayment_rates
>>> compare_capital_repayment_rates(
        mortgage=130_500, interest_rates=[1, 2], mortgage_length_months=300
    )

[
    {'interest_rate': 1, 'repayment': 491.82},
    {'interest_rate': 2, 'repayment': 553.13}
]

Compare the cost of two interest rates for an interest only mortgage.

>>> from mortgagepy.compare import compare_interest_only_rates
>>> compare_interest_only_rates(
        mortgage=130_500, interest_rates=[1, 2]
    )

[
    {'interest_rate': 1, 'repayment': 108.75},
    {'interest_rate': 2, 'repayment': 217.5}
]