在 Tumblr 只有兩個情況會牽涉到年齡：
- 你必須年滿 13 歲才可以使用 Tumblr。我們的服務條款中明確聲明：「我們鄭重聲明：請嚴格遵守這項根據美國聯邦法律的規定。或許你會說你已經 12.9 歲了，但是很抱歉，不行就是不行。如果你未滿 13 歲，請勿使用 Tumblr。請跟你的父母要 Playstation 4 或是看書。
- If we've calculated your age to be under 18—which we do based on the information you gave at signup—Safe Mode is enabled for you and you won't be able to disable it until our system indicates that you are 18.
Since Tumblr just asks for your age, our system only knows your birth year rather than your specific birthday. To figure out if you're 18, our system takes the age you entered and subtracts it from the current year. So to be considered “over 18” by our system in 2017, you would have needed to sign up with an age indicating that your birth year was 1999 or earlier.