Door Term: Investor Calculators

Know the numbers before you make the offer.

Get instant access to two practical deal tools: a seller-financing offer builder and an amortization calculator with rental cash-flow analysis.

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Two tools. Transparent assumptions.

Model the terms and the monthly reality.

The original formulas are preserved, but fixed percentages are now visible and editable so you can model the deal you are actually evaluating.

Calculator 01

Seller financing

Model an above-asking offer, upfront amount, seller-financed principal, monthly payment, interest, and a 10-year balloon schedule.

Offer scenario5-year balloon
Offer price$140,000
Monthly payment$704
Financed$125,000
Rate0.00%
Calculator 02

Amortization & cash flow

Estimate principal and interest, taxes, insurance, management, cash flow, cash-on-cash return, and the remaining balance by year.

Rental analysis30-year term
Monthly cash flow$689
Loan amount$80,000
Monthly P&I$532
Cash on cash37.3%
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Love the calculators? Put your resident communication in Door Term too.

Property MGMT is free for up to five rental units, with private resident portal messaging and the option to connect your own AI. Capacity for 6–20 units is $10/month, and your calculators stay available inside the same dashboard.

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Calculator results are illustrative estimates, not appraisals, offers, lending commitments, tax advice, legal advice, or guarantees. Estimates may omit costs and risks. Verify all assumptions with qualified financial, tax, legal, lending, title, and real-estate professionals before acting.