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 calc force-promotes the scope to full rewire and shows me the budget I’ll actually be held to. The requested-scope dollars get replaced; that’s the move competitor calculators skip, and it’s the move that turns “the seller said partial” into a number my offer can survive.
Rewire Reality — what an inspector will catch and force-promote
Five gotchas the calc surfaces through the leak-check flags, with the per-line behavior the engine actually applies:
- Knob-and-tube wiring.Force-promotes any non-full scope to full rewire. There is no permit-and-inspector path for a partial rewire on a K&T home in any Chicago-metro jurisdiction I’ve worked in — the inspector flags the un-touched K&T circuits and you re-permit. Insurance carriers are the second trap: when a homeowner-policy underwriter spots K&T post-close, they’ll often give 30 days to remediate or lose coverage, which collides with the drywall-hang gate and slides four to six weeks of schedule.
- Aluminum branch wiring (1965-1973).Force-promotes partial and panel-only to full rewire as the conservative SiteworkMath default. Aluminum branch is grandfathered until you touch it; once any circuit is modified or the panel is replaced, every AL/CU device connection has to be addressed. CPSC accepts three compliant repair paths: copper replacement (full rewire), COPALUM crimped connectors installed by a certified specialist, or AlumiConn permanent connectors. The calc defaults to full rewire because COPALUM specialists are rare in most metros and full-house AlumiConn labor often approaches full-rewire cost — but if you have a confirmed COPALUM- or AlumiConn-experienced electrician already lined up, model their bid via the override rather than this scope-promoted number. The right answer depends on what your AHJ, electrician, and homeowner-policy underwriter will accept, not on the calc’s default rule.
- Ungrounded 2-wire circuits.Reality check, no promotion. GFCI compliance is impossible without a ground path — not in the way a competitor calculator might tell you (“just use a GFCI receptacle”), but in the way the inspector will actually call it on a wet-area circuit. Plan for either ground-path retrofits on the affected circuits or a scope expansion to full-rewire on those branches. The calc widens the band and surfaces the warning; it does not silently rewrite the scope, because the right answer depends on how many ungrounded circuits there actually are.
- Visible scorching at the panel.Reality check, no promotion — but it’s the one flag that should make you walk the property a second time. Scorching is a fire-precursor signal, and the scope this calc returns assumes a healthy panel. If the scorching is bad enough that the panel needs emergency replacement, that work doesn’t fit a normal-schedule rewire — you’re paying overtime to a licensed electrician before drywall demo can even start.
- DIY / unpermitted junction boxes. Reality check, and a permit-line multiplier. Inspectors who find one unpermitted box usually require all unpermitted boxes to be brought into compliance during the same permit cycle, which can mean opening more wall than the original scope expected. The calc raises the permit line and the branch line, widens the band, and surfaces the inspection-time warning so you can budget a real number instead of a wishful 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-cluster 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 engine output for that reason.
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 SiteworkMath planning-range feasibility budget for residential electrical rewire work — the dollar number an operator uses to decide walk, bid, or kill before calling licensed electricians. Not a contractor bid. The engine sums six lines (service entrance, panel + breakers, branch circuits, AFCI/GFCI cascade, permit + inspection, fixture allowance) and returns only the lines applicable to the recommended scope. What is INCLUDED: electrician labor, materials, breakers, fixtures, permit + inspection, utility coordination on service-upgrade scopes. What is EXCLUDED: wall repair / patch / paint when fishing through finished drywall (budget separately at $1.5-3/sqft of affected wall area), HVAC re-balancing if you've removed soffits to fish through, and any structural / framing work needed to enlarge an existing service entrance. Pricing anchors are Fixr 2026 + Inch Calculator + Homewyse + Nassau National Cable cost-guide data captured under verbatim quote in this site's competitor intel file. Code references are NEC / NFPA 70 §210.12 (AFCI cascade), §210.8 (GFCI), §230 (service entrance), §250 (grounding), §408 (panels), §314 (box fill), and §110.26 (working space).
Why does this calculator have four scope modes instead of one rewire estimate?
Because the dollars and the inspection consequences are completely different across the four. Every cost-guide aggregator I sourced flattens these into one rewire page with a sqft-driven number, which buries the question that actually matters: which scope are you allowed to do? A K&T home with a 60-amp panel can't legally stop at 'panel-only swap' in any Chicago-metro jurisdiction I've worked in — the inspector force-promotes you to full rewire. The four modes are full rewire (everything), partial rewire (specific rooms with the AFCI 210.12 cascade applied), panel-only swap (panel + breakers + the AFCI breakers feeding bedrooms and kitchens), and service-upgrade only (utility-side amperage upgrade with the panel sized to match). The calc returns the right line set for the recommended scope and dims the rest.
What does 'scope promoted' mean in the Inspection Reality output?
It means the engine returned a different scope than you asked for, because two of the leak-check flags trigger force-promotion under the calc's conservative-underwriting default. Knob-and-tube wiring promotes any non-full scope (partial, panel-only, service-only) to full rewire — most jurisdictions in the Chicago metro will not pass a partial K&T project at the rough-in inspection. Aluminum branch wiring (1965-1973) promotes partial and panel-only to full rewire as the safe default; CPSC also accepts COPALUM crimping and AlumiConn permanent connectors as compliant repair paths, but those depend on having a certified specialist available, so SiteworkMath defaults to copper replacement and asks you to override if you have a confirmed alternative-repair electrician lined up. The Inspection Reality panel renders the engine's reason verbatim so you can see the rule that fired, and the dollar output below is for the recommended scope.
Why is per-square-foot a cross-check output, not a primary input?
Because circuit count and amperage tier drive cost more than square footage does, and competitor calculators that lead with $/sqft inherit a fallacy from the cost-guide aggregators they scrape. A 1500 sqft 1920s home with K&T might run $9-15K on a full rewire (lath-and-plaster access labor); a 2500 sqft 1995 home with NM cable in open framing might run $7-11K (no fish-through, modern feed). Same $/sqft division gives wildly different absolute numbers that the operator can't act on. This calc derives $/sqft from the result so you have the cross-check for sanity ($2-15/sqft full-rewire band), but the inputs that actually drive the math are bedrooms (proxy for circuit count), baths (GFCI count), wiring era (access labor), service amperage tier, and the leak-check flags.
What's the AFCI cascade on a pre-1980 partial rewire and why does it matter?
NEC 210.12 says that substantial renovation of any bedroom, living, dining, or kitchen room triggers AFCI breakers on every circuit serving that room — not just the touched circuits. On a pre-1980 partial rewire, the cascade fires hard because most of the existing circuits are non-AFCI. The calc models this as a separate AFCI/GFCI cascade line, and the Inspection Reality panel surfaces the warning so you don't budget for the partial-scope dollars and then get caught by the inspector requiring AFCI on circuits you weren't planning to touch. AFCI breakers run $40-100 each materials per Fixr 2026, plus install labor — a 6-AFCI cascade on a partial rewire is an extra $400-800 the 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 pencils and whether to call electricians at all. Use the bid as the actual contract number. The feasibility caveat — 'not a contractor bid, the budget I'd use to decide whether to walk, bid, or kill' — is part of the engine output for that reason. If the calc band is wide enough that you can't make the deal pencil at the high end, 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.
Also in this cluster
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.