Chimney Flashing Calculator

Enter your chimney dimensions and roof pitch to see exactly how many pieces of step flashing, counter flashing, and apron material you need — plus a cost comparison across aluminum, galvanized steel, copper, and lead.

Flashing Material

Cricket / Saddle Behind Chimney

Chimney Width (in)

Chimney Depth (in)

Pricing (edit to match local rates)

Step Flashing ($/ea)

Base/Apron ($)

Counter Flash ($/ea)

Back Pan ($)

Cricket Material ($)

Sealant ($/tube)

Step Flashing

8 pieces

4 per side, 5" x 7" each

Counter Flashing

7 pieces

64" total linear, 10" pieces

Best Price

Galvanized Steel

$37.55

Masonry Screws

24 screws

2 per step + 4 apron + 4 back

Purchase Option	Quantity	Est. Cost
Aluminum	17 pcs total	$44.50
Galvanized SteelBest value	17 pcs total	$37.55
Copper	17 pcs total	$123.00
Lead	17 pcs total	$105.50

Cheapest option: Galvanized Steel at $37.55Copper flashing lasts 70+ years and is the gold standard for longevity, but costs significantly more upfront. Aluminum and galvanized steel are the most affordable and work well for 20-30 years. Lead is durable but heavier and increasingly restricted in some areas. Match your flashing material to the expected lifespan of your roof.

Consider adding a cricket behind this chimneyChimneys wider than 30 inches should have a cricket (saddle) installed behind them to divert water and prevent pooling. Without a cricket, wide chimneys create a dam that traps debris and water, leading to leaks over time. Toggle the cricket option above to include materials for one.

This is a material estimate only. Actual flashing quantities may vary based on chimney construction, roof profile, and local building codes. Always consult a roofing professional for complex installations.