The piano hasn’t been tuned in 30+ years. It’s pretty out of tune. After the initial tuning, how out of tune does a piano get after a couple of years. I’m seeing once a year is recommended. Would the piano be terribly out of tune after that period or still playable, but just not great? A professional pianist would probably say this piano is pretty hard to listen to, and I have good relative pitch and I can certainly hear that it’s out of tune and flat overall, but I can still play it.
I guess the question is how long could I get away with not having it tuned?
The longer it goes, the further out of tune it’ll get and the less it’ll be able to hold a tune. You can kick the can down the road as long as your ears can stand it but it’s never going to be cheaper than it is right now, especially if you bring it back to concert pitch.
Conventionally pianos in homes ought to be tuned twice a year - each time you get a major temperature shift owing to seasonal changes, but if it's your piano and you don't have a reason to tune it beyond personal enjoyment then tune it when you want If your mother's piano hasn't been tuned in a long time it might not hold that first tuning for very long as the strings might have some give to them if they haven't been touched in awhile, so you might need a top up. Best thing to do is ask the piano tech who tunes your piano, they'll be able to give you the best advice here
It’ll go out of tune almost instantly if it hasn’t been tuned in that long.
Yeah. Once a year isn’t enough. It may or may not have trouble holding tune. An enormous enemy are the wide swings of humidity we get in many areas of the world. If it’s valuable, install a Dampf Chaser, it’ll pay for itself. I wouldn’t know if the piano is worth it though. You’ll know. Or someone you know will.
It may never be “at pitch” again. It could possibly be in tune with itself but A440 may likely be a distant memory.
If the pin block and pins are in bad condition, it won't even be in tune with itself for long. If the pin block and pins are in good condition, there's no reason it can't be tuned to concert pitch, unless there's a structural flaw in the piano (which is unusual and doesn't happen just from neglect.) If the pin block is fine but the pins are loose, and this trick hasn't been done already, a piano can be "re-pinned" to a larger size and the piano will hold its tune. But that's very unlikely to be worthwhile for this piano -- it only would be on a valuable piano, since it'd be $3K to $6K. So I probably shouldn't even have mentioned it.
There is so much misinformation about this topic, as is evident by this thread. It largely depends on the piano's age and overall condition. If it's 80+ years old or fairly corroded, it may be a problem. However, if the piano is structurally fine and made in the last 70 years, there is no reason it can't be brought back up to 440 and then tuned normally. It doesn't matter if it is 30 cents flat or 200. It may take more passes, but it is perfectly doable within a normal pitch raise and tuning appointment from someone who knows what they're doing. I've tuned thousands of pianos, many of which needed substantial pitch raises. Once they're in tune again, sure they may need to be tuned again in 3-6 months, and then after that at least every 6 to 12 months like any other piano. Even after 6 months many of the worst pitch raises are still fairly close to where I left them and another normal tuning keeps them there. People on here always lament about "oh it won't be able to hold at 440 anymore" or "oh it has been too long and it can't be at 440 anymore" is absolutely BS if the piano is structurally fine with no cracks/separations/issues/rust. Just find and hire a good registered piano technician.
You won't know until you have it tuned (twice.) After that, just see how long you go before you want it tuned again. It could be 4 years. The old advice was when most people didn't have HVAC, so if you have that and keep your home at a relatively consistent temperature and humidity, yearly tuning isn't necessary for a piano whose pinblock is in good condition. But you won't have any idea of the pinblock condition until you have it tuned. You can ask the tech what they think. If you enjoy playing this piano (especially after getting it tuned) then go for it. But note that, especially if it's an upright or baby grand (under 5'6" long) it's probably not worth putting any money into, from a strictly financial viewpoint and functional viewpoint as a player. You'd be better off getting rid of it and buying a used inexpensive digital piano, where $500 will get you something most players would find acceptable. (See this subreddit's FAQ on what to look for in a digital piano, then look on FB Marketplace and Craigslist. In addition to their recommendations, I can recommend any Casio Privia PX-nnn (where nnn is a 3 digit number) of any age, as long as every key works, and feels and sounds like the its neighbors. I once bought (for really cheap) a 1924 Steinway M that was in bad cosmetic shape and which had sluggish action. It had been in a home fire many years before and had been partially restored, including new pinblock, but had been ignored for decades by that time. I fixed the action myself and got it tuned (twice.) After that, it stayed in tune even after moving from NC to Seattle and then from Seattle to SF Bay area, and was still in great tune 3 or 4 total years later, until yet another fire reduced it to ashes and heaped metal. :-(