How are my level and rank calculated, and what do the rank tiers mean?

EXPLANATION

Two values count: Activity Points per week and days with at least 5,000 AP or a session.
Level 1 equals an inactive week, Level 40 the WHO movement recommendation, Level 70 a strong amateur week (Competitor), Level 100 an Ironman training week.
Ranks from the top: 100 Legend, 90–99 Ironman, 80–89 Elite, 70–79 Competitor, 60–69 Endurance Animal, 50–59 Sports Ace, 40–49 Steady Mover, 30–39 Everyday Hero, 20–29 Stroller, 10–19 Starter, 1–9 Couch Potato.
If your actual form sits 15 levels or more away from your level, it gets reset.
You compare via My rank, My country, Rank in country and My city, and countries and cities can also be compared directly.

STEP BY STEP

On your home screen, tap the level number next to your profile picture.
Check your current level and when the next settlement happens.
Switch between My rank, My country, Rank in country and My city.
Use the info icon How your level works for the full explanation and all rank tiers.

COMMON QUESTIONS

Why did my level suddenly drop a lot?

This only happens if your actual form is 15 levels or more away from your current level. It then gets reset.

How often does my level change?

Once a week, by at most two levels up or one level down.

Your level measures your movement over the last four weeks. It's recalculated weekly, rising by at most two levels and falling by at most one. Each block of ten levels carries its own rank name.