The short answer is that the value of gil is vague and therefore completely arbitrary depending on the context.
It's worth noting that attempting to link in-game value to fluff value is pretty much fruitless. For example, battlecraft leves and the individual marks for Clan Centurio hunting bills give around 1,500 gil upon completion, not counting bonuses. Ishgard sells Beef Stew for 415 gil. Factoring in some limited realism--travel time, collecting trophies, etc.--you'd be lucky to buy two or three whole meals even though you travelled to Coerthas Western Highlands and fought three yetis to the death. So the in-game value really cannot be translated to any sort of real world value without running into a huge plethora of inconsistencies and contradictions. So unless every player used the same in-game vendor from which to draw their conversions, it's more or less futile.
If for some reason the narrative demands specific numbers, then I use a simple "10 gil = 1 USD" conversion. A few gil is a paltry sum, a thousand gil is a decent tip, a hundred thousand gil is a respectable sum, and several hundreds of thousands of gil is still relatively wealthy.
I'd rather not speculate on the theory of gil inflation and whether or not it's a currency that uses a metallic standard, but what it comes down to is: avoid using numbers to describe gil.
Besides, as long as we're trying to apply realism then gil should be using denominations anyway like platinum coins to denote one thousand gil or something. Unless adventurers really are hauling around sacks of millions of individual coins.
It's worth noting that attempting to link in-game value to fluff value is pretty much fruitless. For example, battlecraft leves and the individual marks for Clan Centurio hunting bills give around 1,500 gil upon completion, not counting bonuses. Ishgard sells Beef Stew for 415 gil. Factoring in some limited realism--travel time, collecting trophies, etc.--you'd be lucky to buy two or three whole meals even though you travelled to Coerthas Western Highlands and fought three yetis to the death. So the in-game value really cannot be translated to any sort of real world value without running into a huge plethora of inconsistencies and contradictions. So unless every player used the same in-game vendor from which to draw their conversions, it's more or less futile.
If for some reason the narrative demands specific numbers, then I use a simple "10 gil = 1 USD" conversion. A few gil is a paltry sum, a thousand gil is a decent tip, a hundred thousand gil is a respectable sum, and several hundreds of thousands of gil is still relatively wealthy.
I'd rather not speculate on the theory of gil inflation and whether or not it's a currency that uses a metallic standard, but what it comes down to is: avoid using numbers to describe gil.
Besides, as long as we're trying to apply realism then gil should be using denominations anyway like platinum coins to denote one thousand gil or something. Unless adventurers really are hauling around sacks of millions of individual coins.