Make yourself at home, because you're going to be spending a lot of time on this screen.
Okay, FFXIII's upgrading... I imagine it's supposed to be a kind of trial and error system, but in the wise words of Sweet Brown: ain't nobody got time for that. This page attempts to detail the most efficient manner of upgrading, and by efficient, I mainly mean cost-efficient, but also time-efficient. Like, 60:40 in terms of balance, there. Maybe 55:45 in hindsight, since the two are really symbiotic.
Know your limits[]
Because of the tier system, it's not just as simple as ploughing as much EXP as you can get your hands on into whatever it is you're trying to upgrade. Weapons come with three tiers, accessories have two (largely, though the Bangles, Wristbands, Marks, Belts, Bracelets and Armlets can be seen as one long chain of upgrades) - each tier has a max EXP that it can take before it needs a catalyst to upgrade it, and when it does upgrade, it's like a whole new item. For example, if something has a Max EXP of 700, and you put in 1,000, that 300 will not carry over to its Tier 2 incarnation. Yeah.
You need to be aware of the max EXP each weapon/accessory tier can take, because you do not want your effort/gil/metaphorical sweat to be wasted by overshooting the mark due to ignorance. Check out these pages of the wiki before you start any upgrading, to see what kind of numbers you're aiming for:
Multipliers[]
Quite simply, you should not be doing any upgrading without setting up a x3 Multiplier first - unless (and I mean it, only unless) you are super close to your weapon's max EXP and you don't want to overrun it. So which components get you that x3 the most efficiently?
There's a good chance you'll collect enough of these in the field, but you'll probably be doing the majority of your multiplier shopping at Creature Comforts, where each of these components can be bought for 80 gil (2,880 gil for the required 36):
- Sturdy Bone
- Barbed Tail
- Vibrant Ooze
But as you've probably noticed, you've got a lot of random components jangling around in your Inventory. These can also be put to use - if you have 24 of the following, they can also give a x3 Multiplier:
- Otherworldly Bone
- Diabolic Tail
- Transparent Ooze
But I'd only recommend using these as a Multiplier if you have them hanging around - they're not cost effective to purchase, it's cheaper to by 36 of the Sturdy Bone/Barbed Tail/Vibrant Ooze lot than it is to buy 24 of these three.
Components for EXP[]
So now you've set up your Multiplier, what about the best way to actually plough EXP into this thing? It's a simple case of the highest EXP-bearing items are your best bet. The Top 5 for EXP are listed in the table below, along with their potential max EXP (in case you don't already know this, there is no fixed EXP value for each component, it depends on the weapon/accessory you are using it on), and how much they cost, and where you can buy them, except in the case of the Tesla Turbine, Supercharger and Turboprop, which aren't available in your Retail Network.
| Component | Min EXP | Max EXP | Cost (gil) | Shop |
| Ultracompact Reactor | 20,000 | 70,000 | 50,000 | R&D Depot |
| Particle Accelerator | 2,400 | 8,800 | 10,000 | R&D Depot |
| Tesla Turbine | 411 | 1,411 | - | Treasure, Drops and Dismantles* |
| Supercharger | 387 | 1,327 | - | Treasure and Dismantles** |
| Turboprop | 384 | 1,317 | - | Treasure and Dismantles*** |
*Tesla Turbines can be acquired through a chest in the Mah'habara, or dropped from the Anavatapta Warmech and the Aquila Velocycle. They can also be acquired by dismantling Hope's Simurgh, the Nue (Simurgh), or from Lightning's Omega Weapon (Blazefire Saber).
**Supercharger can be found in a chest in the Tesseracts of Orphan's Cradle. It can also be acquired by dismantling Lightning's Omega Weapon (Gladius), or the Adamant Bangle, Wurtzite Bangle, Nimbletoe Boots or the Twenty-sided Die.
***Turboprop can be found in a chest in the Tesseracts of Orphan's Cradle. It can also be acquired by dismantling the Weirding Glyph.
As you can see, the two best exponents are pretty pricey, so know you can also buy the Superconductor, Perfect Conductpr, Chobham Armor and Bomb Cores. However, I really do think it's worth just saving up for the Ultracompact Reactors and the Particle Accelerators, in terms of long term efficiency, it's far more cost-effective.
Catalysts[]
You can buy (almost) all of your catalysts via the Retail Network, but you'll also accumulate a lot of them just from wandering around Pulse and playing through the game (especially Eden/Orphan's Cradle). Since you really want to be saving your gil for pricey components, it's more efficient to go find your catalyst in a Cie'th Mission - that means you get a little more CP to play around with whilst you're at it. I've listed in a table below which missions have which catalysts as rewards, as well as enemy drops and (eh) shops.
| Catalyst | Shop | Cost (gil) | Drop | Reward (Mission No.) |
| Millerite | The Motherlode | 3,000 | PSICOM Executioner (Bresha) | - |
| Rhodochrosite | The Motherlode | 8,000 | PSICOM Warlord (Palumpolum) | 09, 16, 20, 56 |
| Cobaltite | The Motherlode | 17,000 | PSICOM Reaver (Palamecia) | 02, 13, 19, 25 |
| Perovskite | The Motherlode | 30,000 | Sanctum Templar (Orphan's Cradle) | - |
| Uraninite | The Motherlode | 45,000 | Havoc Skytank (Palumpolum) | 29, 30, 26, 57 |
| Mnar Stone | The Motherlode | 60,000 | - | 47, 60 |
| Scarletite | The Motherlode | 100,000 | Adamanchelid, Sacrifice | 50 |
| Adamantite | R&D Depot | 220,000 | - | - |
| Dark Matter | R&D Depot | 840,000 | Shaolong Gui | - |
| Trapezohedron* | R&D Depot | 2,000,000 (!) | Adamantortoise, Long Gui | - |
*See the Obtaining a Trapezohedron page for a full guide on getting these.
My in-game wallet is sobbing uncontrollably[]
Yeah, tears of blood, right? Upgrading is a costly business, which is why I've put together this handy The Art of Farming guide to teach you the ins and outs of grinding to get you lots of gil to splash at the Retail Network. You're welcome.