Using slope app and bike ride data from phone

I had been wondering about the steep slope on my Thai standard bike ride for a while. I had struggled with the idea of getting a carpenters level and measuring distances and calculating to arrive at a slope number. The slope on my bike ride is the steepest I can remember. The climb is not long but it is steep. I had looked around unsuccessfully at GPS apps that require subscriptions or that cost money. I would probably use this one time. It's mostly flat here but I wanted some record of the slope of part of my normal route. When I do the out part of the out and back route I do the big downhill portion. I can easily pass cars on the section of road without pedaling. The steepest downhill is maybe 1/8 mile ending in a hairpin curve.

I found that brief downhill to be 11% grade. That's about what I thought, but it's nice to know. On the other side going up it only registered 10% grade for the return portion. The return is part of a 617 foot climb in elevation. So the length and slope are somewhat significant for an 8 mile route one way.