Measuring Percent of Grade: How to Determine 5% Grade

[F3 guy]

I hope a message board of this caliber can help me.

Here is my problem. How does one measure a percent of grade? Specifically in a ratio or in a liner measurement how would I know what a 5% grade is? I need to ensure a field is within 5%, is that so many inches out of level in a foot, yard, or mile?

Any help would be greatly appreciated.

 

[chroot]

% grade is calculated by comparing vertical rise to horizontal run. Imagine walking 100 feet horizontally while gaining 5 feet vertically; 5 feet is 5% of 100 feet, so the grade is 5%.

- Warren

 

[James R]

In other words, if you measure the height rise h over a horizontal distance d, then the grade is h/d. If you want a percentage, multiply this number by 100.

For example, if the field rises 1 foot over a 20 foot horizontal distance, the grade is 1 in 20, or 1/20. The percentage grade is 1/20 multiplied by 100, which is 5%.

 

[HallsofIvy]

I need to ensure a field is within 5%, is that so many inches out of level in a foot, yard, or mile?

5% of a foot is 5% of 12 in= 0.6 inches.

5% of a yard is 5% of 36 in= 1.8 inches (exactly 3 times 0.6 since a yard is 3 feet).

5% of a mile is 5% of 5280 ft so 5280(0.6)= 3168 in.= 264 ft= 88 yards.

 

[DaveC426913]

So, a 100% grade is 45 degrees?

 

[CRGreathouse]

So, a 100% grade is 45 degrees?

That's right.

 

[F3 guy]

I knew this was the right place to ask! Thank you all very much.