educational estimating tool - not professional advice. every number here is a placeholder until verified. read the full disclaimer.

austin · small sites · september 2026

cost vs rent check

type the lot, the cost and the rent. the page draws the massing those numbers imply and compares the yield on that cost with the hurdle you set. change anything; the drawing and the result follow.

every default below is an assumption, not a fact. the lot, the setbacks, the coverage cap, the efficiency, the unit size, the hard cost, the soft cost, the land cost, the rent, the vacancy, the operating ratio, the cap rate and the spread are all placeholders that make the page work on first load. none of them describe a real site or a real austin market quote. the five checks at the bottom are cited on each card: the parking, site plan lite and drainage cards are checked against city documents; the spread and efficiency cards are rules of thumb and say so. the math is portable, three of the five cards are not - yield on cost, cost and rent are ordinary numbers; swap in your own market's figures and the formula still works anywhere. the parking, site plan lite and drainage cards are Austin, Texas rules and do not apply outside it - see the tools page for more on this.

inputs

lot width (ft)street frontage

lot depth (ft)front to rear

front setback (ft)25 ft is an assumption (MF-3); change it for your district

side setback (ft)each side

rear setback (ft)

storiesmax 5 here

lot coverage cap (%)of lot area

efficiency (%)net rentable of gross

average unit (sf)net rentable per unit

hard cost ($/sf)per gross sf

soft cost (% of hard)

land cost ($)

rent ($/sf/month)per net sf

vacancy (%)

operating expense (%)of effective income

exit cap rate (%)

target spread (bps)yield over cap rate

what the massing does not check. the 55% lot coverage default is the maximum building coverage of MF-3 (25-2-492). MF-3 also limits floor-area ratio and density (25-2-562 sets site area per unit), and this page checks neither, nor height or impervious cover. at the default three stories the building drawn here is well past MF-3's floor-area and density limits, so a massing this large may not be permittable at that coverage. treat the unit count as what the lot geometry and your inputs produce, not as what the zoning allows.

the answer

what the numbers draw

site plan

lot, setbacks, and the footprint that is left

section

stories stacked, net rentable against gross

the arithmetic

line	value	how

how fragile is it

yield on cost when rent and hard cost each move ten percent. the middle cell is the base case.

rent \ hard cost	hard cost -10%	base	hard cost +10%

checks - the assumptions behind the answer

read this before using any of it

the question is always the same. someone owns a lot, or is about to, and wants to know what it can hold and what it might cost against what it might rent for. that answer needs a drawing and a number. they usually come from two firms, on two timelines, for two fees, and by the time both arrive the deal has moved.

the zoning reading is the product. not the drawing on its own and not the estimate on its own, but knowing which rules govern the lot and drawing what they allow, with no firm to spin up. a designer who can read the zoning and draw the answer, working with a cost estimator who can price it, is the whole service.

this page is the front door, not the answer. it shows the shape of the argument in thirty seconds. the real answer needs the real lot, the real zoning, a real cost quote, and a drawing that has been looked at by someone who has built one. if the defaults here made you curious, that is what the page is for.