What is my site worth (fitness, old website, little content, low ad income, great inbound links)

~10 years ago, I created wilkscalculator.com, which is a calculator type tool widely used in the powerlifting/strenght sport community to compare strength between people of different bodywegith. I did not invent the formula, I just implemented it. Formula is used by most powerlifting federations.

I get about 16000 uniques per month currently, down from almost double before the pandemic. Most visitors from US, then Canada, UK.

It is widely linked from many high-ranking sites in the fitness industry (bodybuilding.com, muscleandfitness.com, sherdog.com, myfitnesspal.com, crossfit.com etc etc), from wikipedia, in blogposts, redditposts etc.

I run some ads through an advertising network, but it is earning me ~150USD/mo, and I feel like with this amount of traffic and link juice in the fitness space, it is worth a lot more than simply current advertising-earnings x 20 or whatever multiple is normal in that space.

I just dont have the time/interest/skillset to really take this to the next level, but I feel that if all I can get for it is 20xmonthly ad revenue, I would rather just keep it trucking along, since I dont really need the liquid cash.

Am I mistaken in thinking this is worth more than 20x current ad revenue because of site age, vertical and inbound links? What do you think it could sell for?