Why ridge cap counts matter
Ridge caps protect the highest seam of the roof from wind‑driven rain and uplift. Under‑ordering can halt work, while over‑ordering wastes bundles that may not match later dye lots. This calculator focuses on measurable inputs—linear ridge and hip length, exposure, and bundle coverage—so you can order materials with fewer surprises.
Measure ridge and hip runs correctly
Measure each ridge run along the peak, not the rafter slope. For hips, measure the hip line from eave to ridge. Add separate rows for complex roofs, dormers, and intersecting ridges. If plans show dimensions, confirm them on site because framing adjustments and ridge vents can change final linear footage.
Understand exposure and overlap
Exposure is the length one cap covers after overlap. Many asphalt cap setups land around 5–6 inches (about 127–152 mm) of exposure, but it varies by product and pattern. If you only know the full shingle length and the planned overlap, the calculator can compute exposure as full length minus overlap.
Bundle coverage and packaging realities
Manufacturers often label ridge cap bundles by linear feet covered, such as 20, 25, or 33 feet per bundle. Some purpose‑made caps also list pieces per bundle. Use the wrapper value whenever possible and treat online “typical” numbers as starting points. Enter pieces per bundle to estimate leftovers more realistically.
Waste factors and ridge vent allowances
Waste accounts for end cuts, starter caps, breakage, and alignment corrections. For simple gable roofs, 10% is common; for many hips, short runs, or high wind detailing, 12–15% is safer. If a ridge vent system requires extra cap material or special end plugs, add a small allowance percentage.
Rounding rules and purchasing strategy
You can’t usually buy partial bundles, so rounding up is the standard. The calculator rounds pieces and bundles up, then shows an estimated leftover when pieces per bundle is provided. If you are close to a full bundle, consider future repairs and color matching—an extra bundle can be cheap insurance.
Cost estimating and cost per linear foot
Enter a price per bundle and tax rate to estimate material cost. The tool reports subtotal, tax, total cost, and cost per linear foot (or meter). Cost per length helps compare products with different bundle coverage. Remember this is materials only; labor, vents, fasteners, and underlayment are separate.
Field checks before ordering
Before purchasing, verify three items: ridge cap product type, required exposure per the installation instructions, and bundle coverage printed on the wrapper. Also confirm whether hips use the same cap system as ridges and whether ridge vent components change cap consumption. A five‑minute check prevents costly returns.
FAQs
Do I include hips in the ridge cap count?
Yes. If the same cap shingles cover hips, add hip lengths as separate runs. If your system uses different hip caps, calculate hips separately using the correct exposure and packaging values.
What waste percentage should I use?
Start with 10% for simple gable roofs. Use 12–15% when there are many hips, short ridges, steep slopes, or high‑wind details that increase cuts and handling loss.
What is exposure, and why does it matter?
Exposure is the finished coverage per cap after overlap. Pieces needed equals total ridge length divided by exposure, rounded up. Small exposure changes can noticeably change total caps.
Should I use coverage per bundle or pieces per bundle?
Use coverage per bundle when the wrapper lists linear feet covered. Use pieces per bundle if packaging lists pieces, or if you want leftover estimates. Providing both gives the best check.
How do I measure ridge length accurately?
Measure along the peak line from end to end, not down the slope. For intersecting ridges, measure each segment separately and enter each as its own run to avoid missing short sections.
Does a ridge vent change the cap quantity?
Often it doesn’t change linear footage, but some vent systems require special caps, end plugs, or thicker profiles that increase waste. Use the ridge vent allowance field if your system needs extra material.
Why does the calculator round up bundles?
Roofing materials are typically sold in full bundles or cartons. Rounding up prevents shortages and aligns with how suppliers package product. Leftover pieces are normal and useful for future repairs.