Mortgage Calculator (Google Sheets Style)
Use this calculator to estimate your monthly mortgage payment and preview an amortization schedule. Then copy the Google Sheets formulas below into your own spreadsheet.
How to Build a Mortgage Calculator in Google Sheets
If you searched for mortgage calculator google sheets, you probably want one of two things: a quick estimate of monthly payment, or a full spreadsheet you can customize for different what-if scenarios. The good news is Google Sheets is excellent for both.
At the core, a mortgage calculator uses the PMT function. Then you can layer in taxes, insurance, HOA fees, and PMI to estimate your real monthly housing cost.
Essential Inputs You Need
- Home price: Purchase price of the property.
- Down payment: Cash paid upfront.
- Interest rate: Annual percentage rate (APR).
- Loan term: Usually 15 or 30 years.
- Property tax: Annual local tax amount.
- Home insurance: Annual premium estimate.
- HOA/PMI: Monthly extras, if applicable.
Simple Sheet Layout (Recommended)
Step 1: Create your input cells
You can use this structure:
B2 = Home Price B3 = Down Payment B4 = Interest Rate (as %) B5 = Loan Term (years) B6 = Annual Property Tax B7 = Annual Insurance B8 = Monthly HOA B9 = Monthly PMI
Step 2: Add the core formulas
Loan amount:
=B2-B3
Monthly principal + interest:
=PMT(B4/12,B5*12,-(B2-B3))
Total estimated monthly payment (PITI + extras):
=PMT(B4/12,B5*12,-(B2-B3)) + (B6/12) + (B7/12) + B8 + B9
Create an Amortization Schedule in Google Sheets
A full amortization table helps you see how each payment is split between principal and interest over time.
Suggested columns
- Payment Number
- Beginning Balance
- Payment
- Interest
- Principal
- Ending Balance
Example formulas (starting in row 2)
A2: 1 A3: =A2+1 B2: =$B$2-$B$3 B3: =F2 C2: =PMT($B$4/12,$B$5*12,-($B$2-$B$3)) C3: =C2 D2: =B2*($B$4/12) D3: =B3*($B$4/12) E2: =C2-D2 E3: =C3-D3 F2: =B2-E2 F3: =B3-E3
Drag formulas down for the full loan term (for a 30-year mortgage, 360 rows).
Why Google Sheets Is Great for Mortgage Planning
- Scenario analysis: Instantly compare 6.25% vs 6.75% rates.
- Down payment planning: See how 10%, 15%, and 20% affect payment.
- Refinance modeling: Build side-by-side comparisons.
- Cloud sharing: Collaborate with a spouse, lender, or advisor.
Common Mistakes to Avoid
- Forgetting to divide annual rate by 12 in monthly formulas.
- Using rate as 6.5 instead of 6.5% when your sheet expects decimal format.
- Ignoring taxes and insurance, which can add hundreds per month.
- Confusing principal + interest payment with full monthly housing cost.
Quick FAQ
Does PMT include property taxes and insurance?
No. PMT returns principal + interest only. Add taxes and insurance separately.
Can I calculate biweekly mortgage payments?
Yes. Convert annual inputs to biweekly equivalents and use 26 periods per year.
Can this work for extra principal payments?
Absolutely. Add an “Extra Payment” column in your amortization table and subtract it from balance each period.
Bottom Line
A mortgage calculator in Google Sheets gives you control: clear monthly estimates, full payoff timeline, and flexible what-if analysis. Use the calculator above for a fast estimate, then move the formulas into your own sheet for deeper planning.