Interest Calculation Worksheets

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Use these worksheets to model interest calculations for flat-rate products. Tiered interest uses the partial-balance method described in Calculating the interest.

Spreadsheet files

These CSV files can be imported into Excel, Google Sheets, or another spreadsheet application. Formulas are included and map to the same cell layout described below (column A–D or A–G).

Copy the CSV by clicking the copy icon in the upper-right corner of the code box.
Paste to a text file, save, and provide a .csv file extension.
Import to a spreadsheet application.

Inputs to change

Enter the annual interest rate as a number in B3 (for example, 4 for 4%) and the number of days in the period in B5 (for example, 31). Adjust dates and transaction amounts in columns A–C starting at row 11.

Daily Balance

Daily Periodic Rate,Interest Rate x 1/365,,,,,
Daily Earned Interest,Balance x Daily Rate,,,,,
Interest Rate,4,,,,,
Daily Periodic Rate,=B3/100/365,,,,,
Period,31,,,,,
Interest Paid,Monthly,,,,,
Compound,Daily,,,,,
,,,,,,
,,,,,,
Dates,Transaction,Amount,Ledger Balance,Balance for Interest Calculation,Daily Interest Earned,Accrued Interest
2026-05-01,Deposit,4000,=C11,=D11,=E11*$B$4,=F11
2026-05-02,,0,=D11+C12,=E11+F11+C12,=E12*$B$4,=G11+F12
2026-05-03,,0,=D12+C13,=E12+F12+C13,=E13*$B$4,=G12+F13
2026-05-04,,0,=D13+C14,=E13+F13+C14,=E14*$B$4,=G13+F14
2026-05-05,,0,=D14+C15,=E14+F14+C15,=E15*$B$4,=G14+F15
2026-05-06,,0,=D15+C16,=E15+F15+C16,=E16*$B$4,=G15+F16
2026-05-07,,0,=D16+C17,=E16+F16+C17,=E17*$B$4,=G16+F17
2026-05-08,,0,=D17+C18,=E17+F17+C18,=E18*$B$4,=G17+F18
2026-05-09,,0,=D18+C19,=E18+F18+C19,=E19*$B$4,=G18+F19
2026-05-10,,0,=D19+C20,=E19+F19+C20,=E20*$B$4,=G19+F20
2026-05-11,Deposit,1000,=D20+C21,=E20+F20+C21,=E21*$B$4,=G20+F21
2026-05-12,,0,=D21+C22,=E21+F21+C22,=E22*$B$4,=G21+F22
2026-05-13,,0,=D22+C23,=E22+F22+C23,=E23*$B$4,=G22+F23
2026-05-14,,0,=D23+C24,=E23+F23+C24,=E24*$B$4,=G23+F24
2026-05-15,,0,=D24+C25,=E24+F24+C25,=E25*$B$4,=G24+F25
2026-05-16,Withdraw,-2500,=D25+C26,=E25+F25+C26,=E26*$B$4,=G25+F26
2026-05-17,,0,=D26+C27,=E26+F26+C27,=E27*$B$4,=G26+F27
2026-05-18,,0,=D27+C28,=E27+F27+C28,=E28*$B$4,=G27+F28
2026-05-19,,0,=D28+C29,=E28+F28+C29,=E29*$B$4,=G28+F29
2026-05-20,,0,=D29+C30,=E29+F29+C30,=E30*$B$4,=G29+F30
2026-05-21,,0,=D30+C31,=E30+F30+C31,=E31*$B$4,=G30+F31
2026-05-22,,0,=D31+C32,=E31+F31+C32,=E32*$B$4,=G31+F32
2026-05-23,,0,=D32+C33,=E32+F32+C33,=E33*$B$4,=G32+F33
2026-05-24,Deposit,5000,=D33+C34,=E33+F33+C34,=E34*$B$4,=G33+F34
2026-05-25,,0,=D34+C35,=E34+F34+C35,=E35*$B$4,=G34+F35
2026-05-26,,0,=D35+C36,=E35+F35+C36,=E36*$B$4,=G35+F36
2026-05-27,,0,=D36+C37,=E36+F36+C37,=E37*$B$4,=G36+F37
2026-05-28,,0,=D37+C38,=E37+F37+C38,=E38*$B$4,=G37+F38
2026-05-29,,0,=D38+C39,=E38+F38+C39,=E39*$B$4,=G38+F39
2026-05-30,,0,=D39+C40,=E39+F39+C40,=E40*$B$4,=G39+F40
2026-05-31,,0,=D40+C41,=E40+F40+C41,=E41*$B$4,=G40+F41
,,Average Ledger Balance,=AVERAGE(D11:D41),,,
,,APYe,=(1+G41/D42)^(365/B5)-1,,,
,,,,,,
,,Total Interest Earned,=SUM(F11:F41),,,

Average Daily Balance

Average Daily Balance,Cumulative Balance / Number of Days in Period when account was active,,
Interest Earned During the Period,"ADB x [(1 + Interest rate / # of days in year) ^ Days in Period] - ADB",,
Interest Rate,4,,
Daily Periodic Rate,=B3/100/365,,
Period,31,,
Interest Paid,Monthly,,
Compound,Daily,,
,,,
,,,
Dates,Transaction,Amount,Ledger Balance
2026-05-01,Deposit,4000,=C11
2026-05-02,,0,=D11+C12
2026-05-03,,0,=D12+C13
2026-05-04,,0,=D13+C14
2026-05-05,,0,=D14+C15
2026-05-06,,0,=D15+C16
2026-05-07,,0,=D16+C17
2026-05-08,,0,=D17+C18
2026-05-09,,0,=D18+C19
2026-05-10,,0,=D19+C20
2026-05-11,Deposit,1000,=D20+C21
2026-05-12,,0,=D21+C22
2026-05-13,,0,=D22+C23
2026-05-14,,0,=D23+C24
2026-05-15,,0,=D24+C25
2026-05-16,Withdraw,-2500,=D25+C26
2026-05-17,,0,=D26+C27
2026-05-18,,0,=D27+C28
2026-05-19,,0,=D28+C29
2026-05-20,,0,=D29+C30
2026-05-21,,0,=D30+C31
2026-05-22,,0,=D31+C32
2026-05-23,,0,=D32+C33
2026-05-24,Deposit,5000,=D33+C34
2026-05-25,,0,=D34+C35
2026-05-26,,0,=D35+C36
2026-05-27,,0,=D36+C37
2026-05-28,,0,=D37+C38
2026-05-29,,0,=D38+C39
2026-05-30,,0,=D39+C40
2026-05-31,,0,=D40+C41
,,Average Ledger Balance,=AVERAGE(D11:D41)
,,Interest Earned During the Period,=D42*((1+B4)^B5-1)
,,APYe,=(1+D43/D42)^(365/B5)-1
,,,
,,,
,,Interest Earned During the Period (alternate formula),=D42*((1+B4)^B5-1)
,,Total Interest Earned,=D42*((1+B4)^B5-1)

Updated 3 days ago

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