Roofing Margin Calculator: Find Out If You’re Undercharging

Here’s the ugly truth: most roofing contractors think they’re making 30% margins when they’re actually making 15–20%. The gap comes from three places — waste factor, overhead costs they forgot to include, and the difference between markup and margin (they’re not the same thing, and confusing them costs you thousands per year).

I built this calculator after watching a friend lose $40K in a single year because his “30% markup” was actually a 23% margin once you factored in material waste, insurance, truck payments, and the office manager he forgot to include in job costs. He was profitable on paper and broke in reality.

Plug in your real numbers below. Be honest with the overhead — include insurance, vehicle costs, fuel, office rent, phone, software subscriptions, and any W-2 salaries that aren’t tied to a specific job. That’s the number most roofers leave out, and it’s the number that eats your profit.

Markup vs. Margin: The Math That Costs Roofers Thousands

A 30% markup is NOT a 30% margin. If your job costs $7,000 and you mark it up 30%, you charge $9,100. Your profit is $2,100 — but your margin is $2,100 ÷ $9,100 = 23.1%, not 30%. That 7-point difference across 100 jobs is the difference between growing your business and wondering where all the money went.

The calculator above uses margin math, not markup math. The “target margin” slider shows you what you need to charge to actually keep that percentage as profit. Use it on every bid.

What Should Your Waste Factor Be?

Standard guidance is 10–15% for asphalt shingles on a simple gable roof. Bump it to 15–20% for complex cuts (hips, valleys, dormers). If you’re doing metal or slate, you already know your waste factor is higher. The default in our calculator is 10% — adjust it based on the actual roof geometry.

What Counts as Overhead?

Everything you pay for that isn’t directly tied to a specific job. This includes general liability insurance, workers’ comp, vehicle payments and fuel, office rent, utilities, phone and internet, software subscriptions (roofing software included), office staff salaries, marketing, and equipment maintenance. Most roofing companies run 12–20% overhead. If you’re not sure, start with 15% and refine it once you’ve tracked your actual numbers for a quarter.