Gas Line Install Calculator
Gas line sizing + material takeoff — BTU-load capacity check, black iron / CSST / polyethylene material, fittings + shutoffs + flex connectors, permit + pressure test + labor.
Sum of all connected appliance ratings
Black iron 3/4: ~$4. CSST 3/4: ~$6.
Appliance-grade SS flex line
Auto = run × 0.4 fittings/ft
2–4 hr per drop typical
Result
- Sizing check0.75-in line only carries 169,000 BTU/hr at 40 ft. Need 215,000 BTU/hr. Upsize.
- UPSIZE
- Pipe cost
- $200
- Fittings
- 16 × $8 = $128
- Shutoffs
- $72
- Flex connectors
- $88
- Permit
- $160
- Pressure test
- $120
- Labor
- 16.0 hr · $1,520
- Total installed
- $2,288
This estimate is based on national average costs and may vary by region, project specifics, and market conditions. Use as a starting point for your bids.
How to size a gas line
Two inputs drive sizing: total BTU/hr load and the longest single run from the meter or tank. Look up the smallest pipe that carries your load at that length on IFGC Table 402.4 (NFPA 54 nationally). Add 20% headroom for future appliances — replacement-time upsizes are 3× more expensive than going one size up at install.
Typical appliance BTU loads
| Appliance | BTU/hr input |
|---|---|
| Furnace (residential) | 60,000 – 120,000 |
| Water heater (tank) | 30,000 – 50,000 |
| Tankless water heater | 150,000 – 200,000 |
| Range / cooktop | 40,000 – 65,000 |
| Wall oven | 20,000 – 30,000 |
| Clothes dryer | 22,000 – 35,000 |
| Outdoor grill (built-in) | 50,000 – 90,000 |
| Fireplace (gas log) | 20,000 – 40,000 |
| Pool heater | 200,000 – 400,000 |
Material selection
- Black iron Sch 40 — indoor above-grade, exposed runs in mechanical rooms. Most permits + inspections.
- CSST (Gastite, TracPipe) — flexible, threaded through framing, fast retrofit. Required bonding to electrical ground since 2007 update.
- Polyethylene — underground only. Yellow jacket NG, black propane. Transitions to metal at the riser at grade.
Pricing benchmarks
- Black iron pipe + fittings: $4–7 per LF installed
- CSST kit + fittings: $5–9 per LF installed
- Polyethylene underground: $7–12 per LF installed (includes trench labor)
- Appliance drop (single): $250–500 each (shutoff + flex + tee + nipple)
- Pressure test + final inspection: $100–250 add-on
Frequently asked questions
How do I size a gas line?
By BTU/hr load and run length. Sum your appliance BTU ratings (furnace 80k, water heater 40k, range 65k, dryer 30k = 215k typical home). Find the longest single run from the meter/tank to a fixture. Look up the pipe capacity at that length on IFGC Table 402.4 (or NFPA 54). Choose the smallest size that carries your load with 20% headroom for future appliances.
Black iron vs CSST vs polyethylene — when do I use each?
Black iron (Schedule 40): residential standard for above-grade indoor runs, exposed in mechanical rooms. CSST (corrugated stainless): flexible, faster install through framing, popular for retrofits. Bonded grounding required (IFGC 310.1.1) since the early-2000s lightning issues. Polyethylene: underground only, with risers transitioning to metal at grade. Yellow jacket for natural gas, black for propane.
Does propane really carry more BTU than natural gas?
Yes — about 2.5× per cubic foot (2,500 BTU/ft³ vs ~1,000 BTU/ft³ for natural gas). So a given pipe size carries proportionally more BTU on propane. That's why propane systems often run on smaller line sizes than equivalent natural gas installs.
Do I need a permit for a gas-line install?
Almost always yes. Even adding a single appliance line in most jurisdictions requires a permit and pressure test. Gas work without permit is one of the fastest ways to fail an insurance claim or void a home sale. Permit costs run $80–250 depending on jurisdiction; pressure test inspection runs $80–150 additional.
What's the pressure test procedure?
Cap all ends. Pressurize the line to 1.5× normal operating pressure (typically 25–30 PSI for residential — check your local code). Hold for 15 minutes minimum. Inspector walks the visible joints with soap-bubble solution and checks the manometer for drop. Any leak = locate it (often a fitting), repair, re-test. Pressure tests are non-negotiable; skipping = an automatic fail.
Related calculators
Plumbing Rough-In
NewPer-fixture plumbing takeoff — supply LF (PEX or copper), DWV LF, valve count, fitting count, and labor hours by fixture type.
Labor Burden
NewConvert a wage rate into a true burdened cost including taxes, insurance, workers comp, and PTO.
Shop Rate
NewBuild a defensible shop rate from wage, overhead allocation, and target profit margin.