Sumline

By STEPHEN TROY NYBERG

Overview

Sumline helps real estate professionals get reliable property numbers inside ChatGPT without having to teach the AI how to calculate each scenario. Ask naturally about seller net proceeds, buyer cash to close and monthly housing costs, rental property returns, or fixed-rate mortgage payments. Sumline runs the same deterministic calculation engines used by the Sumline web app and returns the verified figures, assumptions, warnings, and a link to continue the scenario in Sumline. Sumline does not determine loan qualification or affordability and does not provide legal, tax, lending, appraisal, or investment advice.

Tools

buyer_closing_costs

ChatGPT

Estimate a US home buyer's cash to close and full modeled monthly housing payment (principal, interest, property tax, insurance, HOA) using Sumline's live Buyer Closing Costs engine — the same math behind Sumline's on-site calculator, PDFs and shared reports. Use this — not mortgage_payment — for any buyer cash-to-close or full monthly payment question. These figures may inform a broader affordability discussion, but this tool does not calculate income, DTI, borrowing capacity or loan qualification, and must never be used to conclude whether a buyer can afford, qualify for, or should purchase a property. Omitted down payment and rate fall back to Sumline defaults, which must be stated to the user. Returns verified figures that must be used exactly as given, never recomputed or adjusted. Estimate only — not lending, legal, or tax advice.

investor_roi

ChatGPT

Analyze a US rental property investment ("does this deal make sense?") using Sumline's live rental engine — the same math behind Sumline's on-site calculator, PDFs and shared reports. Computes monthly cash flow, cap rate, cash-on-cash return, equity at exit, total and annualized ROI. If property tax and insurance are unknown, ask for them once or state clearly that the figures exclude them. Always report the vacancy, maintenance, management, appreciation and hold assumptions used. Returns verified figures that must be used exactly as given, never recomputed or adjusted. Estimate only — not lending, legal, or tax advice.

mortgage_payment

ChatGPT

Compute the monthly principal-and-interest payment for a fixed-rate US mortgage using Sumline's live amortization engine. Principal and interest ONLY — property tax, homeowner's insurance, HOA dues and mortgage insurance are excluded, and this must be stated to the user. For a buyer's cash to close or full monthly housing payment, use buyer_closing_costs instead. Returns verified figures that must be used exactly as given, never recomputed or adjusted.

seller_net_proceeds

ChatGPT

Estimate a US home seller's net cash at closing ("what will my seller walk away with?") using Sumline's live Seller Net Sheet engine — the same math behind Sumline's on-site calculator, PDFs and shared reports. Ask the user for the property state before calling: without a supported state, transfer tax is assumed $0 and the estimate is not locally accurate. Ask once for the mortgage payoff (mortgageBalance); if unknown, $0 is used and must be disclosed. Use the current fields, not the LEGACY ones. Returns verified figures that must be used exactly as given, never recomputed or adjusted. Estimate only — not lending, legal, or tax advice.