What this estimate is doing
Describing a home and pricing a deal are two different jobs. Size, age, and condition describe the structure. Land rights, whether the home can stay where it sits, moving costs, and nearby sales decide what a buyer will hand over. This calculator runs a depreciation scenario; it doesn't look up market prices.
Know the assumptions you're working with
The math starts at floor area × your replacement-cost input. It drops 15% after the first year, then takes 4% a year off the declining balance, with a floor at 20% of where it started. Condition multipliers run from 0.70 to 1.15, and the optional setting scenario stacks a 1.25 multiplier on top. Those are teaching figures, not measured depreciation rates or a proven land premium.
The main range sits 20% either side of the midpoint. The 50–70% range is a second piece of arithmetic, run before you pay for repairs, moving, holding, and selling. Neither one is a confidence interval, an appraisal, or an offer you should make.
Keep one thing in view while you read them: a home that can't stay put can cost more to haul away than it sells for. Price the removal first and that surprise never reaches you.
Turn serial numbers and ZIP codes into evidence
A serial number identifies a home; it doesn't carry a price. A ZIP code narrows your sales search but says nothing about condition or site rights. There's no serial-number, ZIP-code, or NADA lookup here, so collect that part yourself. HUD explains labels and data plates, and J.D. Power lists manufactured-home report options.
Work backward to your buy number
Start with a resale figure you can support with completed sales. Take out the repair, transport, setup, holding, and selling costs you'll really face, then the margin that pays you for the work and the unknowns. What's left is your ceiling. Look at the land interest and the home interest separately while you're in there, because they can trade to different people.
The mobile-home valuation guide walks through both cases: a home that stays in place and one that has to move. For a whole community's lot income, the park valuation calculator picks up where this one leaves off.
Settle condition and the stay-or-move question, and the rest of this is arithmetic you can finish at the kitchen table.