---
title: "Roof Replacement Cost Calculator | Infinity Roofers"
description: "Use our roof replacement cost calculator for a quick estimate, learn how to measure your roof, then schedule a visit for an accurate price."
url: "https://infinity-roofers.com/roof-replacement-cost-calculator/"
updated: "2026-10-15"
---

# Roof Replacement Cost Calculator

This roof replacement cost calculator turns your roof size in square feet into an estimated re-roof price in seconds. Below it, learn how to measure your roof yourself and what changes the final price. For an accurate price, schedule a roof visit with Infinity Roofers Inc., a licensed California roofing contractor (License #1134192) with locations in Simi Valley, Canoga Park and Pasadena.

## How to calculate your roof's square footage

Roof size is measured by its surface, not by the floor area of the house. A sloped roof with overhangs is larger than the floor under it, so a few minutes with a tape measure gives you a much better number to enter above.

1. **Measure the footprint.** Measure the length and width of the house at the edge of the roof, overhangs included, and multiply them. A house that measures 50 ft by 40 ft at the roof edge has a footprint of 2,000 sq ft. For an L-shaped house, split it into rectangles and add them up.
2. **Find the pitch.** Pitch is how many inches the roof rises for every 12 inches it runs. From the attic, hold a level perfectly horizontal (bubble centered) with one end touching the underside of a rafter, mark 12 inches along the level, then measure straight up from that mark to the rafter: 6 inches means a 6/12 pitch. Step only on joists or boards, never on insulation or drywall between them, and skip this if the attic is hard to reach. Stay off the roof itself.
3. **Multiply by the pitch factor.** The steeper the roof, the more surface it has over the same footprint:
  - 4/12: 1.05
  - 5/12: 1.08
  - 6/12: 1.12
  - 7/12: 1.16
  - 8/12: 1.20
  - 10/12: 1.30
  - 12/12: 1.41
4. **Convert to squares.** Roofers count in squares: one square is 100 sq ft of roof, so divide the total by 100.

**Example:** a 2,000 sq ft footprint with a 6/12 pitch is about 2,000 × 1.12 = 2,240 sq ft of roof, or about 22.4 squares. Enter 2,240 in the calculator. A flat roof needs no pitch factor: its size is simply its length times its width.

Roof sections at different pitches? Measure each section’s footprint, multiply it by its own factor and add them up. A garage, porch or patio cover counts too when it is part of the re-roof.

## What can move your final price

Two roofs with the same square footage can still have very different prices. These are the things that move it:

- **Pitch and access.** A steep roof, a second story or a tight side yard takes more time and more safety setup.
- **Material.** We work with asphalt shingles, tile roofing, metal roofing, and flat roofs tailored to your needs, and each system is priced on its own.
- **Tear-off and decking.** How many old layers come off, and how many deck boards under them need replacing.
- **Code rules for your address.** Fire rating, cool-roof rules and the permit for your city.

Our guide to [roof replacement cost in Ventura County](https://infinity-roofers.com/roof-replacement-cost-ventura-county/) explains each of these, so you can read any estimate line by line and compare two bids fairly.

## Why an accurate price needs a roof visit

The calculator gives you an estimate. For an accurate price, schedule a visit: we inspect and measure your roof and go over the material options with you, so the price fits the roof you actually have.

Every job starts with understanding your goals and inspecting your roof. [Schedule your roof visit](https://infinity-roofers.com/contact/), or read how our [roof replacement](https://infinity-roofers.com/roofing-services/roof-replacement/) service works from the first visit to the final walkthrough.

## Questions about the roof cost calculator

### Is the calculator price a quote?

No. It is an estimate to help you plan. For an accurate price, schedule a visit so we can inspect and measure your roof.

### Should I enter my home's square footage or my roof's?

Your roof’s. Use the steps above to turn your home’s footprint and roof pitch into roof square footage. If you only know your home’s size, enter it for a first number; the roof visit gives you the accurate one.

### Is the price different for tile, metal or flat roofs?

Yes, the material changes the price. The calculator gives a general re-roof estimate, and at the visit we price the system you choose: asphalt shingles, tile, metal or a flat roof.

### Which areas do you serve?

Simi Valley and across Ventura County, Canoga Park and the western San Fernando Valley, and Pasadena and nearby San Gabriel Valley communities. See all [areas we serve](https://infinity-roofers.com/service-areas/). To talk to the team, [contact Infinity Roofers](https://infinity-roofers.com/contact/).