Simple (Flat Rate) Interest Calculator: Calculate the Principal (Initial Starting Amount of Money) To Be Lent, Deposited or Borrowed With a Simple (Flat) Interest Rate in Order To Produce a Sum of Money of 1,000 Units (Dollar, Euro, Pound, etc.) for an Investment Duration Period of 81 Days (2 Months and 20 Days). Annual Simple (Flat) Interest Rate: 10%

Detailed calculations of the principal

Notations and variables used:

Principal (initial amount), P


Due interest, I = 1,000


Annual simple interest rate, R = 10%


From date: Aug 10, 2017

To date: Oct 30, 2017

Duration, T = 81 days (2 Months and 20 Days)


Transaction fee rate, F% = 0%

Transaction fee amount, F


Number of days in a year, N = 365

Calculate P, the principal (the initial amount of money to be lent, deposited or borrowed) to earn the simple (flat rate) interest

The simple (flat rate) interest calculation formula:

I = (P × R × T) ÷ N ⇒


P = (N × I) ÷ (R × T) =


(365 × 1,000) ÷ (10% × 81) =


(100 × 365 × 1,000) ÷ (10 × 81) =


36,500,000 ÷ 810 ≈



45,061.728395061728 ≈


45,061.73

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

E = P + I =


45,061.728395061728 + 1,000 =


46,061.728395061728 ≈


46,061.73


Calculate principal amount to invest to get a certain simple flat rate interest

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

The latest initial amounts of money calculated for earning certain simple flat rate interest amounts

Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 1,000 units (Dollar, Euro, Pound, etc.) for a period of 81 days (2 Months and 20 Days), if the annual simple (flat rate) interest is 10%. Mar 29 09:23 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 2,874.06 units (Dollar, Euro, Pound, etc.) for a period of 30 days, if the annual simple (flat rate) interest is 7%. Mar 29 09:06 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 413 units (Dollar, Euro, Pound, etc.) for a period of 70 days (2 Months and 11 Days), if the annual simple (flat rate) interest is 1.5% and the transaction fee is 0.3%. Mar 29 09:01 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 413 units (Dollar, Euro, Pound, etc.) for a period of 70 days (2 Months and 11 Days), if the annual simple (flat rate) interest is 1.5% and the transaction fee is 0.3%. Mar 29 09:01 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 1,304 units (Dollar, Euro, Pound, etc.) for a period of 335 days (11 Months), if the annual simple (flat rate) interest is 3% and the transaction fee is 0.5%. Mar 29 08:15 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 1,304 units (Dollar, Euro, Pound, etc.) for a period of 335 days (11 Months), if the annual simple (flat rate) interest is 3% and the transaction fee is 0.5%. Mar 29 08:15 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 235,274 units (Dollar, Euro, Pound, etc.) for a period of 452,536 days (14,868 Months), if the annual simple (flat rate) interest is 12%. Mar 29 08:06 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 191 units (Dollar, Euro, Pound, etc.) for a period of 396 days (13 Months), if the annual simple (flat rate) interest is 2.5%. Mar 29 07:58 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 20,000 units (Dollar, Euro, Pound, etc.) for a period of 1,826 days (60 Months), if the annual simple (flat rate) interest is 4.5%. Mar 29 07:57 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 210 units (Dollar, Euro, Pound, etc.) for a period of 365 days (12 Months), if the annual simple (flat rate) interest is 2%. Mar 29 06:28 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 3,028.284 units (Dollar, Euro, Pound, etc.) for a period of 2,192 days (72 Months), if the annual simple (flat rate) interest is 5%. Mar 29 06:21 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 7,000 units (Dollar, Euro, Pound, etc.) for a period of 451,468 days (14,833 Months), if the annual simple (flat rate) interest is 0.7%. Mar 29 06:03 UTC (GMT)
Calculate the principal, initial money amount to be lent, deposited or borrowed in order to earn a simple (flat rate) interest of 105,865,802 units (Dollar, Euro, Pound, etc.) for a period of 7,305 days (240 Months), if the annual simple (flat rate) interest is 13.45%. Mar 29 05:40 UTC (GMT)
All the initial amounts of money calculated by users for earning certain simple flat rate interest amounts


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

Annual simple flat rate interest calculation 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 for the principal - initial amount of money lent, deposited or borrowed in order to produce a simple flat annual rate:

  • S = I ÷ (p% × n)

Examples of how to calculate the initial amount, the principal, to earn a certain simple flat rate interest:

  • 1) What is the principal 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, for an annual simple flat interest rate (percentage) p% = 3.5%?
    Answer:
    S = I ÷ (p% × n) = 3,500 ÷ (3.5% × 5) = 3,500 ÷ (3.5/100 × 5) = (3,500 × 100) ÷ (3.5 × 5) = 350,000 ÷ 17.5 = 20,000 units
  • 2) What is the principal 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, for an annual simple flat interest rate p% = 2%?
    Answer:
    S = I ÷ (p% × n) = 300 ÷ (2% × 3) = 300 ÷ (2/100 × 3) = (300 × 100) ÷ (2 × 3) = 30,000 ÷ 6 = 5,000 units

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

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

The principal formula for earning an annual simple flat rate interest calculated for a period of m months:

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

The principal formula for earning an annual simple flat rate interest calculated for a period of d days:

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

More examples of how to calculate the principal for earning a simple flat rate interest:

  • 1) Calculate the initial amount S that would generate a simple flat rate interest I = 6.67 units in m = 5 months with a simple interest rate of p% = 4%.
    Answer:
    S = (12 × I) ÷ (p% × m) = (12 × 6.67) ÷ (4% × 5) = (12 × 6.67) ÷ (4/100 × 5) = (100 × 12 × 6.67) ÷ (4 × 5) = (100 × 12 × 6.67) ÷ 20 = 5 × 12 × 6.67 = 400.2 ≈ 400 units
  • 2) Calculate the initial amount that would earn a simple flat rate interest I = 7.5 units in m = 5 months with a simple flat interest rate of p% = 4.5%.
    Answer:
    S = (12 × I) ÷ (p% × m) = (12 × 7.5) ÷ (4.5% × 5) = (100 × 12 × 7.5) ÷ (4.5 × 5) = (100 × 12 × 7.5) ÷ 22.5 = 9,000 ÷ 22.5 = 400 units.