How I’d actually use this on a flip
On a Chicago-metro deal, I run the gut rehab calc first to decide whether the property pencils overall. If the electrical line on that breakdown is more than ~12% of hard cost, I drop into this calc and tighten the number. Square footage from the listing, bedrooms and baths from the photos, era from the year built, current service amperage from the panel photo if I have it — and I leave the leak-check flags off until I walk the property.
Second pass is during the walkthrough. Phone in hand, in front of the panel: are the breakers thermal-magnetic only or AFCI? Are the conductors copper or aluminum? Pull a couple of receptacle covers in the hall and the kitchen — knob-and-tube shows up as cloth-jacketed single conductors stapled to the framing, not as romex. If I see two flags, I flip them, and the calculator moves the scope up to full rewire and shows me the budget I’ll actually be held to. The requested-scope dollars get replaced with the recommended-scope dollars — the number my offer has to survive when “the seller said partial” meets what the inspector will actually require.
Inspection reality — small job or full rewire?
The calculator may move you from the job you asked for to the job the house is likely to require. Five conditions drive that decision — each framed as “what you see / what it means / what to do.” The first two are scope-changing on their own; the other three widen the price band and surface inspection-time warnings.
- Knob-and-tube wiring (pre-1950 stock).
What you see: cloth-jacketed single conductors stapled to framing, ceramic insulators at penetrations, no ground wire.
What it means for budget:the calculator moves any scope up to full rewire. There’s no inspector-approved path for a partial rewire on a K&T home in Chicago-metro jurisdictions I’ve worked. Insurance carriers spot K&T post-close and give 30 days to remediate or lose coverage — collides with drywall hang and slides 4-6 weeks.
What to do: budget full rewire from day one. The knob-and-tube replacement cost guide walks the per-circuit math and the lath-and-plaster access labor that makes K&T removal 40-60% costlier than a same-era romex rewire. - Aluminum branch wiring (1965-1973).
What you see:silver-colored solid-strand wiring at receptacles or in the panel. Often marked “AL” or “ALUMINUM” on the cable jacket.
What it means for budget:the calculator moves partial and panel-only scopes up to full rewire as the conservative default. Aluminum branch is grandfathered until you touch it; once you do, the affected aluminum circuits and their AL/CU terminations need an approved repair path, and many inspectors and electricians will price the project as systemic risk — not a one-room fix. Three compliant repair paths exist (full copper replacement, COPALUM crimping, AlumiConn connectors), but COPALUM specialists are rare in most metros.
What to do:budget full rewire by default. If you have an electrician with COPALUM certification or AlumiConn experience lined up, override the calculator’s recommendation with that bid number. The aluminum wiring replacement cost guide breaks down COPALUM vs AlumiConn vs full-rewire in dollars. - Ungrounded 2-wire circuits.
What you see: 2-prong receptacles or 2-conductor cable with no ground wire, common in pre-1965 wiring.
What it means for budget:warning only — the scope doesn’t change. The circuits stay ungrounded after a partial rewire, but ungrounded doesn’t mean “no GFCI option” — NEC 406.4(D)(2) allows GFCI-protected replacement receptacles labeled “No Equipment Ground.” A heavy wet-area remodel (kitchen, bath, laundry) may still trigger broader corrections.
What to do:price either a labeled-GFCI strategy on un-touched circuits or a scope expansion that retrofits ground paths. The right answer depends on how your local inspector reads the project — ask before you bid. - Visible scorching at the panel.
What you see: black or brown scorch marks on or around the breaker panel, melted plastic on breakers, burnt-smell odor in the panel room.
What it means for budget:warning only — the scope doesn’t change. But this is the one flag that should make you walk the property a second time. Scorching is a fire-precursor signal. The scope this calculator returns assumes a healthy panel.
What to do:get a licensed electrician on site BEFORE running this calc seriously. If scorching is bad enough to need emergency panel replacement, that’s overtime labor before drywall demo even starts — not a normal-schedule rewire. - DIY / unpermitted junction boxes.
What you see:twisted-wire connections without proper box enclosures, abandoned splices in walls, “extension cord wiring” behind drywall.
What it means for budget: warning + permit-line multiplier. Inspectors who find one unpermitted box typically require all of them brought into compliance during the same permit cycle. That can mean opening more wall than the original scope expected.
What to do: walk the basement and accessible attic BEFORE bidding. Each unpermitted splice you find pre-bid is $200-500 of budget you can fold in upfront; each one the inspector finds is a re-permit cycle.
Worked example — 1970s ranch with aluminum branch and 100A panel
You walk a 1972 ranch listing, ~1,800 sq ft, three bedrooms, two baths. The listing photo shows a 100A panel; pulling a receptacle cover in the hallway shows silver branch wire stamped “AL.” The seller said the previous owner “upgraded the breakers,” so you assume a panel-only swap is enough.
- Scope you picked: Panel-only swap.
- Flags ticked: Aluminum branch wiring.
- Recommended scope: Full rewire.
- Why it changed:Once you touch the aluminum circuits, those circuits and their AL/CU terminations need an approved repair path under modern code — and many inspectors and electricians will price the whole project as systemic risk rather than a one-room fix. The calculator’s conservative default is full copper replacement for that reason.
- Override path:COPALUM crimps and AlumiConn connectors are both code-compliant repair paths that run cheaper than full replacement. COPALUM requires a certified specialist (rare in most metros); AlumiConn needs an electrician who’s installed the connector before. That’s why the default is replacement, not repair.
- What to ask the electrician:“Are you COPALUM-certified, do you have AlumiConn experience, or do you bid replacement only?” The answer tells you which planning band on the calculator is realistic for this house.
A 1920s bungalow with knob-and-tube in the attic and basement runs the same play, just with a tighter outcome: full rewire is the only inspector-approved path, so there’s no override to negotiate. The number you take to the seller credit conversation is the calculator’s full-rewire band, not the panel-only one.
Methodology
Every dollar number on this page traces to one of three layers: SiteworkMath planning ranges (anchored on Fixr 2026 / Inch Calculator / Homewyse / Nassau National Cable cost-guide data captured under verbatim quote in the site’s competitor intel file), code references (NEC / NFPA 70 sections cited inline in the inspection reality footnote), and operator calibration on Chicago-metro permit-tier behavior. The full per-calculator sourcing tier in methodology spells out which sources back which kinds of claims. The numbers are planning ranges, not contractor bids — the feasibility caveat is part of the calculator output for that reason.
If you want the cost picture without the scope logic, how much does it cost to rewire a house is the standalone read — it walks the same per-circuit and per-amperage cost layers in prose, anchored on the same Fixr / Inch / Homewyse / Nassau data, without the calculator. And if the scope you actually need is a service amperage upgrade (utility-coordination dollars, meter base, what changes between 100A and 200A), 200-amp service upgrade cost isolates that line item.
Show the formulas
- Branch circuits:
circuitCount × $200-400 each × eraMult × fishMult × labelMult. Era multiplier is 1.4× pre-1950 (lath-and-plaster), 1.15× 1950-1979, 1.0× 1980-2000, 0.95× post-2000. Fish-through 1.4× when walls are finished. Owner-with-permit 0.75× labor. - Service entrance + panel: tier-keyed by target amperage. 100A combined ~$2-3.5K mid; 200A ~$4-7K mid; 400A ~$13-18K mid. Includes utility coordination, meter base, main, grounding electrode, and panel + breakers. Auto-included on full-rewire only when the target amperage is higher than current (or visible scorching is flagged on the panel) — same-amperage full rewires that keep an adequate panel skip these lines.
- Excluded scope: wall repair / patch / paint when fishing through finished drywall ($1.5-3/sqft of affected wall area), HVAC re-balancing if soffits had to come down, and structural / framing work to enlarge a service entrance. The calc surfaces an exclusion note above the line table when finished drywall is checked so the gap is visible, not buried.
- AFCI/GFCI cascade:
afciCount × $40-100 + gfciCount × $5-100, plus breaker install labor ~50% of total. AFCI count derived from bedroom count + scope + era; GFCI count from bath count + scope. - Permit + inspection: fast $75-300 / typical $125-500 / strict $350-1500. DIY junction boxes flag adds 30%.
- Confidence band: high ±10% / medium ±18% / rough ±32%, plus ±4% per active leak flag.
- Scope promotion:K&T promotes any non-full scope to full rewire; aluminum branch promotes partial / panel-only to full rewire. Reality checks (ungrounded, scorching, DIY boxes, AFCI cascade) surface as warnings without promoting scope.
- Engine logic:
lib/sitework/electrical/electrical.tswith pricing anchors indefaults.tsand types intypes.ts. Tested inelectrical.test.ts.
Frequently asked
What does this electrical rewire cost calculator estimate?
A planning-range budget for residential rewire work — the dollar number you'd use to decide whether to call a licensed electrician at all. Not a contractor bid. It covers electrician labor, materials, breakers, permit and inspection fees, and utility coordination on service-upgrade scopes. The output splits into six lines (service entrance, panel + breakers, branch circuits, AFCI / GFCI breakers, permit, fixture allowance) and dims any line outside the recommended scope. What sits outside the number: wall patch and paint after fishing wire through finished drywall, HVAC re-balancing if you drop soffits, and structural work to enlarge an existing service entrance.
Why does this calculator have four scope modes instead of one rewire estimate?
Because the dollars and the inspection consequences are different across the four. Cost-guide aggregators flatten all four into one $/sqft page, which buries the question that actually decides the budget: which scope are you legally allowed to do? The four modes are full rewire (whole house), partial rewire (specific rooms with AFCI added automatically), panel-only swap (breakers replaced, wires stay), and service upgrade only (utility-side amperage step like 100A to 200A, panel sized to match). Why scope can move up: a knob-and-tube home with a 60-amp panel can't legally stop at panel-only in most Chicago-metro jurisdictions. The inspector will require full rewire. The calc returns the right line set for the scope the inspector will actually accept.
What does 'scope promoted' mean in the inspection warning?
The calculator returned a different scope than the one you asked for, because a property flag makes the smaller job unrealistic at inspection. Knob-and-tube wiring promotes any non-full scope up to full rewire. Aluminum branch wiring (1965-1973) promotes partial and panel-only up to full rewire as the safe default. The Consumer Product Safety Commission also accepts COPALUM crimping and AlumiConn connectors as repair paths — both require a certified specialist, so the calc defaults to copper replacement and lets you override. The inspection-warning panel above the dollar output spells out the rule that fired. The dollar number is for the recommended scope, not the one you originally picked.
Why is per-square-foot a cross-check output, not a primary input?
Because circuit count and wiring era drive rewire cost more than square footage does. Calcs that lead with $/sqft inherit a fallacy from the cost-guide aggregators they scrape. A 1,500 sq ft 1920s home with knob-and-tube runs $9,000-$15,000 on a full rewire (lath-and-plaster access labor). A 2,500 sq ft 1995 home with modern cable in open framing runs $7,000-$11,000 (no fish-through). Same $/sqft input — wildly different absolute numbers. The calc uses bedrooms (proxy for circuit count), baths (GFCI count), wiring era (access labor), service amperage tier, and the property flags. It derives $/sqft from the result so you get the cross-check ($2-$15/sqft typical band) — but $/sqft isn't an input.
What's the AFCI cascade on a pre-1980 partial rewire and why does it matter?
Code requires arc-fault breakers on every circuit serving a substantially renovated bedroom, living, dining, or kitchen room — not just the circuits you actually touch. The rule cascades into rooms you weren't planning to rewire. Pre-1980 partials get caught hardest because most existing circuits are non-arc-fault. The cascade fires across the whole room every time. The calc models this as its own line so you don't budget for the partial-scope dollars and get blindsided at rough-in inspection. AFCI breakers run $40-$100 each in materials, plus install labor. A six-breaker cascade is an extra $400-$800 cost-guide aggregators don't model.
What's the difference between this calc and a contractor bid?
A contractor bid prices the specific scope on the specific property with the specific access conditions. This calc prices the scope category on a typical property in your jurisdiction tier. Use the calc to decide whether the project is worth calling electricians at all. Use the bid for the contract number you'll sign. The walk-away test: if the calc's high band is wider than the deal can survive, walking before paying for inspections and bids is exactly what the calc is for.
What I’d do next
- Plug this number into the gut-rehab feasibility calc
If the electrical scope is one line on a larger rehab, take the mid from this calc and override the electrical line on the gut-rehab cost calc.
- Sequence the rewire against demo, drywall, and inspection gates
Electrical rough-in is gated by demo and frame inspections, and gates drywall on the back end. The timeline calc shows the critical-path slot.
- Read the planning-range methodology
What's anchored, what's a planning range, and how the Fixr/Inch/Homewyse/Nassau cross-check works against operator calibration.
By James Wu. Pricing anchors: Fixr 2026 panel + service entrance tables, Inch Calculator 2026 circuit + permit ranges, Homewyse rewire baseline (12 circuits), Nassau National Cable rewire size bands — captured under verbatim quote in the site’s competitor intel file. Code references: NEC / NFPA 70 §210.12 (AFCI), §210.8 (GFCI), §230 (service entrance), §250 (grounding), §408 (panels), §314 (box fill), §110.26 (working space). Engine logic in lib/sitework/electrical/electrical.ts. Numbers are SiteworkMath planning ranges, not contractor bids — feasibility framing is part of the output for that reason. Not a substitute for a licensed electrician’s site visit. Full methodology.