FREE ONLINE CALCULATORS · NO SIGN-UP

Clear answers,
real formulas.

Key Calculators is a small, growing library of free tools. Every calculator is built on a sourced formula and checked by hand — new ones added every week.

✓ Sources cited   ✓ No account needed   ✓ Mobile friendly

FASCIA & SOFFIT COST CALCULATOR — SAMPLE RESULT

150 LF fascia + 150 LF soffit, vinyl, user-entered rates

Net eave length 300 LF
Waste allowance 10%
Rates User-entered
Planning total Use local rates

Transparent linear-foot pricing, local rates only, and a contractor quote comparison.

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Every formula is shown on the page — no hidden math.

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No login, no email wall. Open a tool and get your number.

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Small library today, built to grow one careful tool at a time.

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Works cleanly on your phone, tablet, or laptop — no squinting or pinch-zooming.

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The library so far

We’re adding calculators one at a time. Every tool goes live only once its formula has been researched, cross-checked and explained in plain language on the page. Have an idea? Tell us what to build next.

Fascia & Soffit Cost Calculator

Estimate soffit and fascia cost per linear foot with local material and labor rates, optional drip edge and gutters, then compare a contractor quote against a transparent planning total.

Roof Replacement Cost Calculator

Estimate roof replacement cost from multi-section measurements and local material and labor rates, then compare a contractor quote against a transparent planning total.

Roof Square Footage Calculator | Free & Accurate 2026

Reviewed: September 2026. This page explains a planning method for measuring roof surface area; it is not a substitute for a final professional takeoff or a roof inspection. Use the following roof square footage calculator to turn your roof measurements into an estimated sloped area, roofing squares and material-planning quantities, whether you start with one … Read more

House Repiping Cost Calculator [Free 2026 Estimate]

Use this house repiping cost calculator to estimate a planning range before you contact a plumbing contractor. Enter your home size, pipe material, number of stories, foundation type, and fixture count. The tool estimates a standard interior domestic water-supply repipe. Not sure if you need one yet? See the warning signs below, then run the … Read more

What should we build next?

Every new calculator starts from a real question someone searched for. Tell us yours.

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Building this library one tool at a time.

Have a calculator you can’t find anywhere else? Tell us and we’ll consider building it next.