How Many Roofing Shingles Do I Need for San Rafael, CA Homes?
- GBR Marketing
- Apr 7
- 2 min read
Updated: Apr 11

Calculating the amount of roofing shingles you will need for a shingle replacement can seem like a daunting task. Fortunately, you will not need to climb a ladder and count the shingles on your San Rafael, CA. Home. Here is how you can calculate the number of shingles you will need.
How to calculate how many roofing shingles do I need?
Calculating the amount of roof shingles you will need for your roofing project requires some simple math. Follow this step-by-step guide to get an accurate estimate.
1. Identify the Planes of your Roof
The first step in calculating the number of shingles you will need is to find the total area of your roof. Start by identifying how many planes are present on your roof. A plane is a flat square section of roofing. For example, if you have a simple A-frame roof with no additional overhangs, you will have two planes.
2. Find the Area of Each Pane
After you have identified the individual planes that make up your roof, you will need to find the area of each plane. You can find the area by multiplying the length of the pane by the width of the pane. This will give you the square footage of each pane on your roof.
3. Calculate the Total Area of your Roof
Once you have measured the area of each of your planes you can find the total area of your roof by adding each plane’s area together.
4. Factor in the Pitch of Your Roof
The pitch, or steepness, of your roof will also affect the number of shingles you will need. To determine the additional shingles you will need for your slope, you will need to apply a multiplier to the total area of your roof. You can find roof slope multiplier tables online or follow the general rule of adding 5% per 10 degrees of pitch. Once you determine what your roof slope multiplier is, you can multiply it by the total area of your roof to determine the number of shingles you will need.
5. Consider Standard Coverage
Now that you know the total area and slope of your roof you can calculate how many bundles of shingles you will need. A standard bundle of shingles covers roughly 33 square feet. Divide the total area of your roof with the slope multiplier by 33 to see how many bundles you will need.
6. Round Up for Waste
Once you divide the total area by 33, round the number up to account for any broken shingles and additional coverage. It is always better to have slightly more than you need instead of not enough.
Let GBR Roofing Do the Math
Instead of calculating the number of shingles you’ll need to reroof your San Rafael home, trust the experts at GBR Roofing to do the math for you. Our certified roofers will ensure that your roof is done the right way. Contact GBR Roofing for a consultation and expert roofing solutions tailored to your needs. Call us at (855) 478-3292 or visit our North Bay location at 2175 Francisco Blvd E, San Rafael, CA 94901 to learn more!