Interest on increasing capital amount, not compounded

Bizzybee

New Member
Joined
Feb 22, 2017
Messages
10
I am hoping someone can help. I have spent all afternoon trying to figure this one out, to no avail.

Basically, I have a principal amount which stays the same and recurrs daily, say £10 (see table below).

I want to add interest on that at 8% simple annual interest from the date it is incurred to a specified end date.

I then want to do the same for the next £10 that are incurred on the next day.

The end date is always the same. So each day a principal amount is incurred, but it has one day less interest on it that the amount the day before.

I would like a formula which will work it all out in one or two (or three) steps. The data I have covers many years and I have baout 3,000 sets to work out. So I can't be doing it all individually as below.

Can anyone help?

[TABLE="class: grid, width: 500"]
<tbody>[TR]
[TD]Principal[/TD]
[TD]Start Date[/TD]
[TD]End Date[/TD]
[TD]Annual Simple
interest rate[/TD]
[TD]Daily interest[/TD]
[TD]No of days[/TD]
[TD]Interest total[/TD]
[/TR]
[TR]
[TD]£10[/TD]
[TD]1 Jan 2015[/TD]
[TD]31 Dec 2015[/TD]
[TD]8%[/TD]
[TD]0.002191781[/TD]
[TD]364[/TD]
[TD][TABLE="width: 64"]
<tbody>[TR]
[TD="align: right"]0.797808219[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[/TR]
[TR]
[TD]£10[/TD]
[TD]2 Jan 2015[/TD]
[TD]31 Dec 2015[/TD]
[TD]8%[/TD]
[TD]0.002191781[/TD]
[TD]363[/TD]
[TD][TABLE="width: 64"]
<tbody>[TR]
[TD="align: right"]0.795616438[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[/TR]
[TR]
[TD]£10[/TD]
[TD]3Jan 2015[/TD]
[TD]31 Dec 2015[/TD]
[TD]8%[/TD]
[TD]0.002191781[/TD]
[TD]362[/TD]
[TD][TABLE="width: 64"]
<tbody>[TR]
[TD="align: right"]0.793424658[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[/TR]
[TR]
[TD]£10[/TD]
[TD]4 Jan 2015[/TD]
[TD]31 Dec 2015[/TD]
[TD]8%[/TD]
[TD]0.002191781[/TD]
[TD]361[/TD]
[TD][TABLE="width: 64"]
<tbody>[TR]
[TD="align: right"]0.791232877[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[/TR]
[TR]
[TD]£10[/TD]
[TD]5 Jan 2015[/TD]
[TD]31 Dec 2015[/TD]
[TD]8%[/TD]
[TD]0.002191781[/TD]
[TD]360[/TD]
[TD][TABLE="width: 64"]
<tbody>[TR]
[TD="align: right"]0.789041096[/TD]
[/TR]
[TR]
[TD="width: 64, align: right"][/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[/TR]
</tbody>[/TABLE]
 
Thank you, but the issue is yhat I dont have the daya in a table. I would have to make 3000 tables otherwise. The table above was just for illustration.
 
Upvote 0

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Thank you, but the issue is yhat I dont have the daya in a table. I would have to make 3000 tables otherwise. The table above was just for illustration.

Is your data sorted by client and if yes, are there id's for each client?
 
Upvote 0
Hi Bizzybee,
give this table a look

[TABLE="class: grid"]
<tbody>[TR="bgcolor: #DAE7F5"]
[TH][/TH]
[TH]A[/TH]
[TH]B[/TH]
[TH]C[/TH]
[TH]D[/TH]
[TH]E[/TH]
[TH]F[/TH]
[/TR]
[TR]
[TD="align: center"]1[/TD]
[TD="align: center"]3[/TD]
[TD="align: center"]2[/TD]
[TD="align: center"]1[/TD]
[TD="align: center"]0[/TD]
[TD]time[/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]2[/TD]
[TD="align: center"]10[/TD]
[TD="align: center"]10[/TD]
[TD="align: center"]10[/TD]
[TD="align: center"]10[/TD]
[TD]payments[/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]3[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]4[/TD]
[TD]10*,08*3/365[/TD]
[TD]10*,08*2/365[/TD]
[TD="align: center"]10*,08*1/365[/TD]
[TD]10*,08*0/365[/TD]
[TD]interest formula[/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]5[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]6[/TD]
[TD="align: center"]0,006575342[/TD]
[TD="align: center"]0,004359562[/TD]
[TD="align: center"]0,002191781[/TD]
[TD="align: center"]0[/TD]
[TD]interest[/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]7[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]8[/TD]
[TD="align: center"]10*0,08/365[/TD]
[TD="align: center"]*[/TD]
[TD="align: center"](3+2+1+0)[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]9[/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"]=[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]10[/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"]3/2*4[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]11[/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"]=[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]12[/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"]Combin(4,2)[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]13[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: center"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]14[/TD]
[TD="align: center"]10*0,08/365[/TD]
[TD="align: center"]*[/TD]
[TD]#fulldays/2*(#fulldays+1)[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]15[/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: center"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[/TR]
[TR]
[TD="align: center"]16[/TD]
[TD="align: center"]example 5 days[/TD]
[TD][/TD]
[TD]4 full days + present day (without interest)[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: center"]17[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: center"]18[/TD]
[TD]10*,08/365*(4/2*5)[/TD]
[TD][/TD]
[TD]0,021917808[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: center"]19[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD="align: center"]20[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]
Foglio4

the compact formula is:

=10*0.8/365*combin(fulldays+1, 2)

Hope this helps and you like it. Have a good weekend
 
Last edited:
Upvote 0
in compact formula there was a typo
=10*0.8/365*combin(fulldays+1, 2)
the amended one is
=10*0.08/365*combin(fulldays+1, 2)

there is an issue with leap yers but the workaround is to divide by 366 this way

=10*0.08/366*combin(fulldaysIN366+1, 2) for periods included in leap years
and former formula
=10*0.08/365*combin(fulldaysIN365+1, 2) for periods included in regular years

Have a nice sunday
 
Upvote 0

Excel 2010
ABCDE
1Amount$10
2Rate8%0.000219per day
3Number50
4Interest$48.44Total$548.44
4a
Cell Formulas
RangeFormula
C2=B2/365
B4=SUMPRODUCT(B1*ROW(INDIRECT("A1:A"&B3)),B3+1-ROW(INDIRECT("A1:A"&B3)))*C2
D4=B1*B3+B4


50 days @ 10 and total interest


The interest on a series can be calculated with SumProduct.
Try the concept that I prepared with a small example and review it with Formula Evaluation.
Edit as required for your requirements.
 
Upvote 0
This may be closer to the calculation that you require.
What result did you calculate?


Excel 2010
ABCD
1Amount$10
2Rate8%0.000219per day
3Number364
4Interest$145.60Total$3,785.60
4a
Cell Formulas
RangeFormula
C2=B2/365
B4=SUMPRODUCT(B1*ROW(INDIRECT("A1:A"&B3)))*B2/365
D4=B1*B3+B4
 
Upvote 0
You do not have to use the Named Cells; you can just reference the relevant cells.

The image did not post correctly so I deleted it.

The formula is

=(Num+1) / 2*Num*Prin*Int / 365 or =(B3+1) / 2*B3*B1*B2/ 365 compared to

the SumProduct version

=SUMPRODUCT(Prin*ROW(INDIRECT("A1:A"&Num)))*Int/365


Excel 2010
ABCD
1Amount$10
2Rate8%0.000219per day
3Number364
4Interest$145.60$145.60$145.60
5Total$3,785.60
4a
Cell Formulas
RangeFormula
B4=SUMPRODUCT(Prin*ROW(INDIRECT("A1:A"&Num)))*Int/365
B5=Prin*Num+B4
C4=(Num+1) / 2*Num*Prin*Int / 365
D4=(B3+1) / 2*B3*B1*B2/ 365
Named Ranges
NameRefers ToCells
Int='4a'!$B$2
Num='4a'!$B$3
Prin='4a'!$B$1
 
Last edited:
Upvote 0
No feedback from Bizzybee.

Try whichever approach you prefer. It is not necessary to use named ranges.
I would not use the formula with Indirect.
I included B___P's suggestion (Combin)


Excel 2010
ABCDE
1Amount10
2Rate8%0.000219per day
3Number364
4Interest145.60145.60145.60
5Total$3,785.60145.60
6
4a
Cell Formulas
RangeFormula
B5=Prin*Num+C4
C4=(Num+1)/2*Num*Prin*Int_Day
D4=(B3+1)/2*B3*B1*B2/365
E4=10*Int_Day*COMBIN(Num+1, 2)
E5=SUMPRODUCT($B$1*ROW($A$1:INDEX($A:$A,$B3)))*C2
Named Ranges
NameRefers ToCells
Int='4a'!$B$2
Int_Day='4a'!$C$2
Num='4a'!$B$3
Prin='4a'!$B$1
 
Last edited:
Upvote 0

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