LoanMonitorLoanMonitor Docs
GuidesDay Count Conventions

30E/360 (Eurobond)

30E/360 Eurobond basis (thirty_e_360): the 31st becomes the 30th on both ends, February is not adjusted. Used for Eurobonds and some international loans.

API value: thirty_e_360

Also known as: 30E/360, Eurobond Basis, 30/360 ICMA, Special German (in older ISDA wording)

30E/360 is the European 30/360 variant used in bond markets. Like all 30/360 methods it assumes a 360-day year, but it only adjusts the 31st of a month. February keeps its real length.

Rules

The formulas use these symbols:

SymbolMeaning
Y1,M1,D1Y_1, M_1, D_1Year, month and day of the start of the interest period
Y2,M2,D2Y_2, M_2, D_2Year, month and day of the end of the interest period
ddInterest days of the period
BBRemaining balance during the period
rrAnnual interest rate as a decimal (4.00 % = 0.04)

Step 1: adjust the days. Before counting:

  • If D1D_1 is the 31st, it becomes 30.
  • If D2D_2 is the 31st, it becomes 30.
  • The end of February is not adjusted, neither at the start nor at the end of a period, and neither on the maturity date.

Step 2: count the interest days.

Formula:

d=360⋅(Y2−Y1)+30⋅(M2−M1)+(D2−D1)d = 360 \cdot (Y_2 - Y_1) + 30 \cdot (M_2 - M_1) + (D_2 - D_1)

With the terms:

Days=360⋅(End year−Start year)+30⋅(End month−Start month)+(End day−Start day)\text{Days} = 360 \cdot (\text{End year} - \text{Start year}) + 30 \cdot (\text{End month} - \text{Start month}) + (\text{End day} - \text{Start day})

With the example numbers: period from 28 February 2026 to 31 March 2026. D1=28D_1 = 28 stays 28, because February is not adjusted. D2=31D_2 = 31 becomes 30.

d=360⋅(2026−2026)+30⋅(3−2)+(30−28)=0+30+2=32d = 360 \cdot (2026 - 2026) + 30 \cdot (3 - 2) + (30 - 28) = 0 + 30 + 2 = 32

Step 3: calculate the interest.

Formula:

I=B⋅r⋅d360I = B \cdot r \cdot \frac{d}{360}

With the terms:

Interest=Balance⋅Rate⋅Days360\text{Interest} = \text{Balance} \cdot \text{Rate} \cdot \frac{\text{Days}}{360}

With the example numbers: 100,000 EUR at 4.00 % for the 32 days above.

I=100,000⋅0.04⋅32360=355.56I = 100{,}000 \cdot 0.04 \cdot \frac{32}{360} = 355.56

What this means in practice

  • Months with 30 or 31 days accrue exactly 1/12 of the annual interest.
  • A period ending on 28 February is 2 days short (1 day in a leap year). The following period starting on 28 February is 2 days long. Over the year the two even out, so a full year still accrues exactly the nominal rate.
  • The effect is a shift of interest from February into March. On annuity loans this changes the interest/principal split of those two installments and, very slightly, the remaining balance.

Example

100,000 EUR at 4.00 % p.a., balance unchanged.

PeriodActual days30E/360 daysInterest
31 Jan → 28 Feb 20262828311.11
28 Feb → 31 Mar 20263132355.56
31 Mar → 30 Apr 20263030333.33
15 Feb → 28 Feb 2026 (broken period)1313144.44
31 Jan 2026 → 31 Jan 2027 (12 monthly periods)3653604,000.00

How to recognise it in a contract

  • "30E/360", "30E/360 (Eurobond Basis)" or "30/360 (ICMA)" in the day count fraction clause.
  • Typical for Eurobond documentation and some internationally syndicated or Schuldschein loans.

A German lender that writes just "30/360" almost always means German 30/360, not 30E/360. Pick 30E/360 only when the contract names it explicitly or the bank's plan shows the February/March shift described above.

German 30/360

German 30/360 (thirty_e_360_de): every month counts as 30 days, including February and the maturity date. The standard for German bank loans.

30/360 US (Bond Basis)

30/360 US Bond Basis (thirty_360): the 31st at the start becomes the 30th; the 31st at the end only if the period started on the 30th or 31st. Common in USD documentation.

On this page

Rules
What this means in practice
Example
How to recognise it in a contract
Related
30E/360 (Eurobond) · LoanMonitor Docs