numpy_financial.nper#

numpy_financial.nper(rate: float | Decimal | floating[Any] | integer[Any] | bool | object_, pmt: float | Decimal | floating[Any] | integer[Any] | bool | object_, pv: float | Decimal | floating[Any] | integer[Any] | bool | object_, fv: float | Decimal | floating[Any] | integer[Any] | bool | object_ = 0, when: str | int | NDArray[Any] | Iterable[str | int] = 'end') → float#
numpy_financial.nper(rate: _CanArrayAndLen[floating[Any] | integer[Any] | bool | object_] | _NestedSequence[float | Decimal | floating[Any] | integer[Any] | bool | object_], pmt: float | Decimal | _CanArray[floating[Any] | integer[Any] | bool | object_] | _NestedSequence[float | Decimal | floating[Any] | integer[Any] | bool | object_], pv: float | Decimal | _CanArray[floating[Any] | integer[Any] | bool | object_] | _NestedSequence[float | Decimal | floating[Any] | integer[Any] | bool | object_], fv: float | Decimal | _CanArray[floating[Any] | integer[Any] | bool | object_] | _NestedSequence[float | Decimal | floating[Any] | integer[Any] | bool | object_] = 0, when: str | int | NDArray[Any] | Iterable[str | int] = 'end') → NDArray[float64]
numpy_financial.nper(rate: ArrayLike | _NestedSequence[Decimal] | Decimal, pmt: ArrayLike | _NestedSequence[Decimal] | Decimal, pv: ArrayLike | _NestedSequence[Decimal] | Decimal, fv: ArrayLike | _NestedSequence[Decimal] | Decimal = 0, when: str | int | NDArray[Any] | Iterable[str | int] = 'end') → Any

Compute the number of periodic payments.

decimal.Decimal type is not supported.

Parameters:
ratearray_like

Rate of interest (per period)

pmtarray_like

Payment

pvarray_like

Present value

fvarray_like, optional

Future value

when{{‘begin’, 1}, {‘end’, 0}}, {string, int}, optional

When payments are due (‘begin’ (1) or ‘end’ (0))

Notes

The number of periods nper is computed by solving the equation:

fv + pv*(1+rate)**nper + pmt*(1+rate*when)/rate*((1+rate)**nper-1) = 0

but if rate = 0 then:

fv + pv + pmt*nper = 0

Examples

>>> import numpy as np
>>> import numpy_financial as npf

If you only had $150/month to pay towards the loan, how long would it take to pay-off a loan of $8,000 at 7% annual interest?

>>> print(np.round(npf.nper(0.07/12, -150, 8000), 5))
64.07335

So, over 64 months would be required to pay off the loan.

The same analysis could be done with several different interest rates and/or payments and/or total amounts to produce an entire table.

>>> rates = [0.05, 0.06, 0.07]
>>> payments = [100, 200, 300]
>>> amounts = [7_000, 8_000, 9_000]
>>> npf.nper(rates, payments, amounts).round(3)
array([[[-30.827, -32.987, -34.94 ],
        [-20.734, -22.517, -24.158],
        [-15.847, -17.366, -18.78 ]],

       [[-28.294, -30.168, -31.857],
        [-19.417, -21.002, -22.453],
        [-15.025, -16.398, -17.67 ]],

       [[-26.234, -27.891, -29.381],
        [-18.303, -19.731, -21.034],
        [-14.311, -15.566, -16.722]]])
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