ARV Calculator – After Repair Value from Comps (with the 70% rule)

Understanding the after repair value (ARV) calculator — concept and principle

This calculator estimates a property's after repair value (ARV) from comparable sales of renovated homes nearby, then applies an investor rule such as the 70% rule to find a maximum purchase price. It also shows the price-per-area range of the comps and how much is left for costs and profit. Use it when evaluating fix-and-flip deals or renovation projects.

The comps' average price per square foot times the subject's size gives the ARV of about $300,900.

How it is calculated

Price per unit area of each comp = sale price ÷ floor area.
ARV = average comparable price per unit area × floor area of the property.
Rule share of ARV = ARV × rule % (for example 70%).
Maximum purchase price = rule share − repair cost.
Left for costs and profit = ARV − maximum purchase price − repair cost.

Use the same area unit (square feet or square metres) for all inputs.

The principle

The sales comparison approach values a property by what buyers recently paid for similar ones. Dividing by floor area puts homes of slightly different sizes on a common scale. The 70% rule is an investor rule of thumb: buying at no more than 70% of ARV minus repairs leaves about 30% of ARV to cover buying and selling costs, holding costs, financing and profit. It is not an official standard, and markets with thin margins or high costs may need a lower percentage.

Worked example

Default inputs: comps $310,000 / 1,550, $295,000 / 1,480, $328,000 / 1,620; property 1,500; repairs $45,000; rule 70%.

Prices per unit area: 200.00, 199.32, 202.47; average $200.60.
ARV = 200.60 × 1,500 ≈ $300,897.
Rule share = 0.70 × 300,897 ≈ $210,628.
Maximum purchase price = 210,628 − 45,000 = $165,628.
Left for costs and profit = 300,897 − 165,628 − 45,000 = $90,269.

Each point is the calculator re-run with only “Floor area of the property (same unit)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Floor area of the property (same unit)	After repair value (ARV)
375	$75,224
750	$150,448
1,125	$225,673
1,500	$300,897
1,875	$376,121
2,250	$451,345
3,000	$601,793

How to read the result

The ARV is only as good as the comps: they should be recent sales of similar homes, in the same area, already renovated to the level you plan. A narrow price-per-area range, as here, suggests a consistent market. The maximum purchase price is a ceiling for negotiation, not a target.

Common mistakes

Using asking prices or old sales instead of recent closed sales.
Mixing renovated and unrenovated comps.
Underestimating repair costs; contingencies are common.
Treating the 70% rule as a guarantee of profit.

Keep in mind: A professional appraisal adjusts each comp for location, lot, age and features. Use this as a first screen only. This is not financial or investment advice.

Frequently asked questions

What does ARV mean in real estate?

The estimated market value of a property after planned repairs or renovation.

Is the 70% rule always right?

No. It is a rule of thumb; costs, financing and local margins may justify a different percentage.

How many comps should I use?

Appraisers commonly use at least three recent, similar sales.

Sources: Sales comparison approach (average comparable price per unit area × subject area); the 70% rule is an investor rule of thumb with no official source

Checked 9 Nov 2026. Sales-comparison estimate (average comparable price per unit area × subject area): standard appraisal arithmetic. The 70% rule is an investor rule of thumb with no official source.

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