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Simple interest calculator

Calculate simple interest (I = P × r × t) and the maturity amount on a principal for a term in years, months or days.

Aktualisiert Geprüfte Beispiele: 5

$
%
Ausprobieren
Zinsen
$
Zinsen: $1,800.00
Nachkommastellen: 2; Zum nächsten Wert, bei Gleichstand zur geraden Ziffer
Total amount
$11,800.00
Interest per year
$600.00
Amount if compounded yearly
$11,910.16

At 6% simple interest, $10,000.00 earns $600.00 a year, so $1,800.00 over the term. Compounding yearly at the same rate would give $110.16 more.

Amount at maturity

$11.8Kat maturity
Kapital84.7%Zinsen15.3%

Balance over time

$10K$10.5K$11K$11.5K0123Years
Simple interestCompounded yearly
Interest by year Zeilen: 3
PeriodInterest in periodInterest so farSaldo
Year 1$600.00$600.00$10,600.00
Year 2$600.00$1,200.00$11,200.00
Year 3$600.00$1,800.00$11,800.00
So wird gerechnet S

  1. Time in years

    t=3=3t = 3 = 3

  2. Zinsen

    I=Prt=10,000.00×0.06×3=1,800.00I = P r t = 10{,}000.00 \times 0.06 \times 3 = 1{,}800.00

  3. Total amount

    A=P+I=10,000.00+1,800.00=11,800.00A = P + I = 10{,}000.00 + 1{,}800.00 = 11{,}800.00

    Rounded half-to-even to 2 decimals for display only.

Über Simple interest calculator

Simple interest is paid only on the original principal: I = P × r × t, where r is the yearly rate as a decimal and t the time in years. A term in months is divided by 12, and a term in days by 365 (actual/365) or by 360, the banker's year some lenders and money markets use. The amount due at maturity is A = P(1 + rt).

With the defaults, 10,000 at 6% for 3 years earns 600 a year and 1,800 in total, for a maturity amount of 11,800. Compounded yearly at the same rate, the same deposit would reach 11,910.16, which is 110.16 more.

Interest here never earns interest of its own. Savings accounts and most deposits compound, so use the compound interest calculator for them; simple interest suits short loans, flat-rate quotes and interest accrued between coupon dates.

Durchgerechnete Beispiele

10,000 at 6% for 3 years

Kapital
10,000
Interest rate (per year)
6%
Zeit
3
Time in
Jahre
Zinsen
1,800.00
Total amount
11,800.00
Amount if compounded yearly
11,910.16

Prüfquelle: 10000 × 0.06 × 3 by hand; 10000 × 1.06³ = 11910.16 (Python decimal)

5,000 at 8% for 9 months

Kapital
5000
Interest rate (per year)
8%
Zeit
9
Time in
Monate
Zinsen
300.00
Total amount
5,300.00

Prüfquelle: 5000 × 0.08 × 9/12 by hand

20,000 at 7.5% for 90 days, actual/365

Kapital
20,000
Interest rate (per year)
7.5%
Zeit
90
Time in
Days
Days in a year
365 (actual/365)
Zinsen
369.86

Prüfquelle: 20000 × 0.075 × 90/365 = 369.8630… (Python decimal)

Same loan on a 360-day year

Kapital
20,000
Interest rate (per year)
7.5%
Zeit
90
Time in
Days
Days in a year
360 (banker's year)
Zinsen
375.00

Prüfquelle: 20000 × 0.075 × 90/360 by hand

Fragen

How do you calculate simple interest?

Multiply the principal by the yearly rate and by the time in years: I = P × r × t. 10,000 at 6% for 3 years earns 10,000 × 0.06 × 3 = 1,800, so 11,800 is repaid. For a term in months, divide by 12 first: 5,000 at 8% for 9 months earns 5,000 × 0.08 × 9/12 = 300.

How do you calculate simple interest for a number of days?

Divide the days by the day-count basis before multiplying. 20,000 at 7.5% for 90 days earns 20,000 × 0.075 × 90/365 = 369.86 on an actual/365 basis, and 375.00 on a 360-day banker's year. Excel's ACCRINTM function uses basis 3 for actual/365 and basis 2 for actual/360.

How do you find the rate or the time from simple interest?

Rearrange I = P × r × t. The rate is r = I ÷ (P × t): earning 1,800 on 10,000 over 3 years means 1,800 ÷ 30,000 = 6% a year. The time is t = I ÷ (P × r): earning 3,000 on 10,000 at 6% takes 3,000 ÷ 600 = 5 years.

Is simple interest better than compound interest?

For a borrower, yes; for a saver, no. Simple interest grows in a straight line, while compound interest also earns interest on interest. On 10,000 at 6%, the gap is only 110.16 after 3 years (1,800 against 1,910.16), but after 20 years simple interest totals 12,000 while yearly compounding adds 22,071.35.

Wie genau arbeitet „Simple interest calculator“?

Die Genauigkeit hängt von Ihren Eingaben und den Annahmen der Methode ab. Die Dezimalrechnung nutzt 50 signifikante Stellen, doch Schätzungen, numerische Verfahren und Quelldaten können ungenauer sein. Die angezeigte Rundung beseitigt diese Grenzen nicht. Anhand unabhängiger Quellen geprüfte Rechenbeispiele: 5. Beispielsweise wird „10,000 at 6% for 3 years“ anhand von 10000 × 0.06 × 3 by hand; 10000 × 1.06³ = 11910.16 (Python decimal) geprüft.

Woher stammt die Methode?

OpenStax Prealgebra 2e — Simple Interest Applications (I = Prt); Brealey, Myers & Allen — Principles of Corporate Finance, ch. 2 (simple vs compound interest); Microsoft Excel ACCRINTM function (simple interest accrued to maturity, basis 2 = actual/360, 3 = actual/365).

Über diesen Rechner

I=P⋅r⋅t,A=P(1+rt)I = P \cdot r \cdot t,\qquad A = P(1 + r t)

Quellen

  1. OpenStax Prealgebra 2e — Simple Interest Applications (I = Prt)
  2. Brealey, Myers & Allen — Principles of Corporate Finance, ch. 2 (simple vs compound interest)
  3. Microsoft Excel ACCRINTM function (simple interest accrued to maturity, basis 2 = actual/360, 3 = actual/365)

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Anhand von Quellen geprüft

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