Lately, I’ve written a few articles about stairs. One important topic I want to cover now is how is the slope of a stairway calculated. It’s one of those things that might sound a bit technical at first, but it’s actually pretty simple once you know what it means.
Let’s start with the word slope. Maybe you haven’t heard it used when talking about stairs before. The slope is just the angle or steepness of the staircase—how much it rises compared to how far it goes forward. Think of it like this: if a staircase goes up very fast in a short distance, that’s a steep slope. If it rises slowly over a longer distance, that’s a gentler slope.
Knowing how the slope of a stairway is calculated is really useful. It’s not just for builders or architects. It helps make sure the stairs are safe and comfortable to walk on. A stairway that’s too steep can be hard to climb and even dangerous. One that’s too flat might feel awkward or take up too much space.
So in this guide, I’ll walk you through how to figure out the slope of your stairs in a simple way—just using a few measurements and easy math.
How is The Slope Of a Stairway Calculated
Step-by-step:
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Measure the total rise: To measure the total rise, just measure the height from the bottom of the stairs to the very top. Start at the floor where the stairs begin and go straight up to the floor where the stairs end. Don’t measure along the slope—go straight up, like measuring the height of a wall.
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Measure the total run: To measure the total run, measure how far the stairs go forward from the very first step to the last one. Start at the front edge of the bottom step and go straight across to the front edge of the top step. Keep the tape measure level, not following the slope.
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Divide rise by run (slope ratio): Once you have both numbers—total rise and total run—just divide the rise by the run. That gives you the slope ratio. For example, if the rise is 36 inches and the run is 48 inches, you do 36 ÷ 48 = 0.75. That number is your slope ratio.
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Optional: Use a calculator or app to convert slope ratio to degrees: If you want to know the slope in degrees, you can use a calculator or a free app. Just type in your slope ratio and look for the “arctangent” or “atan” function. It will give you the angle in degrees. So if your slope ratio is 0.75, the calculator will show about 37 degrees. There are also online tools where you just enter the numbers, and it does it for you.
What’s a Good Stair Slope?
A good stair slope usually falls between 30 and 37 degrees. That range feels natural and safe when going up or down. It’s not too hard on your legs, and you don’t feel like you’re climbing or stretching too much. That’s why most building codes stick to this range.
If the angle is over 38 degrees, the stairs can feel steep and tiring. They might even be unsafe, especially for kids or older adults. If the angle is under 30 degrees, the stairs can feel too flat and take up a lot more space than needed.
Extra Tips for Outdoor Stairs on a Slope
Adjusting for uneven ground
If you're measuring slope on uneven ground, start by finding the highest and lowest points of where the stairs will go. That gives you the total rise. Then measure the distance between those two points to get your total run. You might need to level out small areas with gravel or digging so your measurements are accurate and your steps stay even.
Give each step a slight slope
Tilt the surface of each tread just a little so water can drain off—especially important for outdoor stairs. About a 1/8 inch drop per foot is enough to keep water from pooling and making steps slippery.
Conclusion
Calculating the slope is just one of the many steps to think about when building your own stairs. I hope this guide helped make things clearer and easier to understand. Whether you're planning a new set of stairs or just curious about how it all works, you're one step closer to getting it done right
If you have questions or need help choosing the right stair parts, feel free to contact us. And if you're looking for durable, stylish handrails to complete your staircase, explore our handrail collection to find the perfect fit.
