Is the 21 JR Pass worth it

So I did the math on if getting a 21 day JR pass would save me money on my itinerary, and it came out almost the exact same (JR pass is more expensive by 100yen). I'm wondering if there are any bonus reason's I'd go with the JR pass over just purchasing tickets seperately? Like would I save a lot of money on transit within a city, do I get discounts anywhere... etc. Looking for advice!

If it costs about the same, I'd get the pass. It's easier than having to visit the ticket booth/machine so many times, plus the pass gives you more flexibility to change your itinerary at will.

Such small differences are negligible anyway as they are outweighed by exchange rate fluctuations and fees charged by your particular pass seller, among other things. It's not an exact science.

How is your itinerary and timeline?

For your JR railway trips for multiple long-distance sections,
the total amount of the regular fees
is easily overestimated to be higher than what you actually should pay,
especially when you are not familiar |
the calculator which you use is not in accordance with some rules.
e.g.
the rule for a round-trip discount on long-distance basic fares,
the rule for a discount on a Limited Express surcharge
regarding a connection between a Shinkansen train and a (non-Shinkansen) Limited Express train.

Being able to just waltz past the manned desk while flashing your pass is a perk.

Being able to just waltz past the manned desk while flashing your pass is a perk.

and don't forget to say "multi-pass!" ---- "multi-pass!" while doing so :-)

Free seat reservations.

While I agree with PPs on the advantages, no one has yet mentioned the disadvantage that you cannot take Nozomi Shinkansen. most trains between Tokyo and Osaka are Nozomi and they are quicker.

Also depending on your itinerary people often initially over estimate how many day trips they are going to do and in the end end up NOT going to some of those places (eg Nikko) because they just need a day without travel. If that happens you�fd be no longer at the break even point.

Enjoy your trip to Japan!

Sorry forgot one point.
Two 7 day passes for some trips might also work. Eg first 4 days in Tokyo w/o pass then activate the first 7 days. Travel around and finish in Kyoto. Stay there for 4-5 days. No pass. And then get an other one and continue traveling around a lot, ending up again in Tokyo for the last few days. (Assuming you travel in/out if Tokyo).
Just a thought.
For travel in a smaller region there are also regional passes that might work wonders in addition or replacement.

A 21-day pass costs only 1130 yen more than two 7-day passes. Consider that the JR pass will also cover local JR trains in Tokyo (they cover much of the city with frequent service), and a few local area buses, which will probably be enough to completely offset the 1130-yen difference. See these details:
https://www.japan-guide.com/e/e2361.html

As far as "most" of the Tokyo-Osaka shinkansen being Nozomi...there are so many non-Nozomi trains, we never find that a problem. You will want to check the schedules for the fastest non-Nozomi, however, to reduce time on the train.

Of course, depending on your specific itinerary, a combination of shorter JR and/or regional passes might prove cheaper. The pass comparison pages on this site are very good and clear.