Simple (Flat Rate) Interest Calculator: Calculate the Annual Simple (Flat) Interest Rate of the Invested Amount of Money (Principal, Initial Starting Amount Lent, Deposited or Borrowed), of 690 units (Dollar, Euro, Pound, etc.) To Produce a Sum of Money of 624 units, for a period of 2,585 days (85 Months)

Detailed calculations of the simple (flat) interest rate

Notations and variables used:

Principal (initial amount), P = 690

Amount produced by the interest, I = 624

From date: Feb 28, 2018

To date: Mar 28, 2025

Duration, T = 2,585 days (85 Months)

Transaction fee rate, F% = 0%

Transaction fee amount, F

Number of days in a year, N = 365

Calculate R, the annual simple (flat) interest rate to earn the amount I

The simple (flat rate) interest calculation formula:

I = (P × R × T) ÷ N ⇒


R = (N × I) ÷ (P × T) =

100% × (N × I) ÷ (P × T) =

((100 × N × I) ÷ (P × T))% =

((100 × 365 × 624) ÷ (690 × 2,585))% =

(22,776,000 ÷ 1,783,650)% ≈


12.769321335464% ≈

12.77%

Calculate E, the amount earned after adding to the principal the amount produced by the simple (flat rate) interest

E = P + I =

690 + 624 =

1,314


Used symbols: % percent, ÷ divide, × multiply, = equal, ≈ approximately equal.

Writing numbers: comma ',' used as thousands separator, point '.' used as a decimal mark.

Simple (flat) interest rate, more calculations:

» Calculate the simple (flat) interest rate of the invested amount (principal, initial starting amount of money lent, deposited or borrowed), of 636 units (Dollar, Euro, Pound, etc.) to produce an amount of 564 units, for a period of 2,585 days (85 Months).

» Calculate the simple (flat) interest rate of the invested amount (principal, initial starting amount of money lent, deposited or borrowed), of 744 units (Dollar, Euro, Pound, etc.) to produce an amount of 684 units, for a period of 2,585 days (85 Months).

Calculator: annual simple interest rate to negociate to earn a certain amount

Annual simple flat interest rate = (Simple flat rate interest × Number of days in a year) ÷ (Principal × Duration in days)

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All the annual simple flat interest rates calculated by users


How to calculate / negociate the simple flat interest rate of a principal - initial starting amount of money lent, deposited or borrowed, in order to collect or pay a certain simple flat rate interest by the duration and any additional transaction fees (withdrawal, payment in advance, etc.).

Annual simple flat rate interest formula:

  • I = S × p% × n

  • I = n years simple interest charged
  • S = initial amount (principal)
  • p% = annual simple flat interest rate (percentage of the principal, charged as interest)
  • n = number of years of the lending or borrowing the money

  • Formula of the simple flat interest rate applied on the principal - initial starting amount of money lent, deposited or borrowed, in order to earn a simple flat annual rate:

  • p% = I ÷ (S × n)

Examples of how to calculate the simple flat interest rate on the principal amount in order to earn a certain simple flat rate interest:

  • 1) What is the simple flat interest rate of the principal S = 20,000 units that has to be lent, deposited or borrowed, for a period of n = 5 years, if the simple flat rate interest collected or paid D = 3,500 units?
    Answer:
    p% = I ÷ (S × n) = 3,500 ÷ (20,000 × 5) = 3,500 ÷ 100,000 = 3.5 ÷ 100 = 3.5%
  • 2) What is the simple flat interest rate of a principal S = 5,000 units, that has to be lent, deposited or borrowed, for a period of n = 3 years, if the simple flat rate interest collected or paid D = 300 units?
    Answer:
    p% = I ÷ (S × n) = 300 ÷ (5,000 × 3) = 300 ÷ 15,000 = 3 ÷ 150 = 1 ÷ 50 = 2 ÷ 100 = 2%

Annual simple flat interest rate formula calculated for a period of n years:

  • Simple flat interest rate, p% = I ÷ (S × n)
  • Interest, I = S × p% × n
  • Principal, S = I ÷ (p% × n)
  • Number of years of the period of the deposit, lending or borrowing, n = I ÷ (S × p%)

Formula of the simple flat interest rate of the principal for an annual simple flat rate interest calculated for a period of m months:

  • Simple flat interest rate, p% = (12 × I) ÷ (S × m)
  • Interest, I = (S × p% × m) ÷ 12
  • Principal, S = (12 × I) ÷ (p% × m)
  • Number of months of the period, m = (12 × I) ÷ (S × p%)

Formula of the simple flat interest rate of a principal for an annual simple flat rate interest calculated for a period of d days:

  • Simple flat interest rate, p% = (365 × I) ÷ (S × d)
  • Interest, I = (S × p% × d) ÷ 365
  • Principal, S = (365 × I) ÷ (p% × d)
  • Number of days of the period, d = (365 × I) ÷ (S × p%)

More examples of how the simple flat interest rate of a principal for a simple flat rate interest formula works:

  • 1) Calculate the simple flat interest rate of the initial amount S = 400 units that would generate a simple flat rate interest I = 6.67 units in m = 5 months.
    Answer:
    p% = (12 × I) ÷ (S × m) = (12 × 6.67) ÷ (400 × 5) = (12 × 6.67) ÷ 2,000 = 80 ÷ 2,000 = 4%
  • 2) Calculate the simple flat interest rate of the initial amount S = 400 units that would generate a simple flat rate interest I = 7.5 units in m = 5 months.
    Answer:
    p% = (12 × I) ÷ (S × m) = (12 × 7.5) ÷ (400 × 5) = 90 ÷ 2,000 = 4.5%.