RO DataZone - Game Mechanics

Atk:

Atk stands for Attack and gives an indication of how much damage you will do when you hit something.
The visible components of the Atk score are your Strength plus the Atk of the weapon you are using on the left and the damage bonus from any pluses the weapon might have on the right.
The real value on the left of your Atk score includes hidden bonuses from Strength, Dexterity and Luck.
For fists, the true value is equal to: STR + [STR/10]^2 + [DEX/5] + [LUK/5] where [] indicates you round the value inside down before continuing and ^2 indicates squaring.
For weapons, the true value is equal to: STR + [STR/10]^2 + [DEX/5] + [LUK/5] + WeaponAtk + AtkBonusCards where [] indicates you round the value inside down before continuing and ^2 indicates squaring.
For missile weapons, the true value is equal to: DEX + [DEX/10]^2 + [STR/5] + [LUK/5] + WeaponAtk + AtkBonusCards where [] indicates you round the value inside down before continuing and ^2 indicates squaring.
Not counting the value of WeaponAtk and AtkBonusCards, this true value is often referred to as the base damage. This base damage is basically the your Atk with bare fists.

MAtk:

MAtk means Magic Attack and gives an indication of how much damage a spell will do when cast against something.
MAtk comes in two parts. The left-hand number is referred to as Min MAtk or Minimum Magic Attack. The right-hand number is referred to as Max MAtk or Maximum Magic Attack. Any time you use a magical attack, a random number between the Min Matk and Max Matk is generated and that number is used as the attack power (base damage) of every hit in that spell.
Min MAtk is equal to INT + [INT/7]^2 where [] indicates you round the value inside down before continuing and ^2 indicates squaring.
Max MAtk is equal to INT + [INT/5]^2 where [] indicates you round the value inside down before continuing and ^2 indicates squaring.
Note that any weapon that gives a +15% bonus to MAtk does not change the number you can see in your status window, but is included in damage calculations.

Hit:

Hit refers to your ability to hit a target. It is the opposite of Flee.
Each point of Hit increases your ability to hit a target by 1%.
Your Hit is a combination of your Base Level, Dexterity and any special Hit increasing cards you may have equipped. It is calculated as BaseLevel + DEX + Cards.
The Mummy card when put in a weapon you are wielding increases your Hit by 20. This is effectively the same as the description which says your Hit is increased by 20%.

Critical:

Critical is your chance of striking a critical blow against a target.
Each point of Critical increases your ability to cause a critical by 1%.
Your Critical on the Status window is equal to 1 + [LUK/3] + Critical Increasing Cards where [] indicates you round the value inside down before continuing.
Your true Critical value is equal to 1 + LUK*0.3 + Critical Increasing Cards.
There is a special rule for Katar wielding Assassins. They get twice the Critical number they should do.
Criticals are checked for before seeing if your Hit overcomes the targets Flee. So you can actually land a Critical even if you would ordinarily have no chance of hitting at all!
Monsters have Luk too! Your chance of getting a critical against a monster is reduced by MonsterLuk/5. This reduction takes place after the doubling of Criticals for Katars and the Counter Attack skill.
The full formula for Criticals at the time of a swing is equal to (1 + YourLUK*0.3 + Critical Increasing Cards)*CritModifier - TargetLUK/5.
A Critical hit always hits for maximum damage and ignores Def.
You can tell a critical has landed by the big red spiky bubble around the damage message and a special hit sound reserved for critical hits.

Def:

Def means Defence and refers to your ability to reduce damage inflicted on you.
The left-hand part of Def is derived from items of Armor (including any pluses on them) and reduces damage by a percentage. The true value of Armor DEF is BasicArmor + Refinements*2/3. That is, you take the full amount of whatever it says in your armors descriptions and any armor adding cards, but only two-thirds of the pluses on your armor. eg. +6 Plate is actually worth 10 + 6*2/3 = 14 DEF. Use this "true value"
The right-hand part of Def is derived from your VIT and reduces damage by that number of points after the left-hand part is applied.
VIT Defense for Players is calculated as [VIT*0.5] + rnd([VIT*0.3], max([VIT*0.3],[VIT^2/150]-1)) where [] indicates you round the value inside down before continuing and rnd(x,y) indicates that you use a random number between the values of x and y. If y is less than x, then it becomes equal to x. max(x,y) indicates you should take the greater of x and y.
VIT Defense for Monsters is VIT + rnd(0,[VIT/20]^2-1) where [] indicates you round the value inside down before continuing and rnd(x,y) indicates that you use a random number between the values of x and y. In other words, a random number between 0 and your vit divided by 20 and rounded down, then squared minus 1. As an example, 63 vit would mean each hit does 0-8 less damage (determined randomly on each hit).
Def can never reduce damage inflicted below 1 point.

MDef:

MDef means Magical Defense and refers to your ability to reduce magical damage inflicted on you.
The left-hand part of MDef is derived from items of Armor (only the MDEF portions) and reduces damage by a percentage.
The right-hand part of MDef is derived from your INT and reduces damage by that number of points after the left-hand part is applied. There is a hidden bonus of VIT/2 to this part of MDEF.
MDef can never reduce damage inflicted below 1 point.

Flee:

Flee is a measurement of your ability to dodge attacks made on you. It is the opposite of Hit.
The left-hand part of flee is derived from your Base Level, Agility and any Flee enhancing cards. It is calculated as BaseLevel + AGI + Cards.
Every 1 point of the left-hand part of flee increases your probability of dodging by 1%. The minimum chance of dodging is 0% and the maximum chance is 95%. No matter what, a monster always has a chance of hitting you. It's kind of like a critical chance for monsters.
The right-hand part of flee is derived from Luck. It is calculated as 1 + [LUK/10] where [] indicates you round the value inside down before continuing.
Every 1 point of the right-hand part of flee gives you a 1% chance to get a "Lucky" dodge. This lucky dodge is calculated before the other kind of dodge and separately from it. Even if you had 0% chance to dodge based on the left-hand part of flee, a lucky dodge can still save you!

ASpd:

ASpd stands for Attack Speed and is a measurement of your ability to swing fast.
ASpd is improved by your Job, the Weapon Speed of the Weapon/s you are wielding, your Agility and your Dexterity.
ASpd is calculated as 200 - Delay.
Delay is calculated as Delay = SpeedMods * (WeaponDelay - ([WeaponDelay*Agi/25] + [WeaponDelay*Dex/100])/10). Delay should be rounded up to the nearest whole number.
Speed Mods come from anything that gives a speed boost, such as potions, skills and special weapons. The benefits are cumulative. Formula for speed mods is (100-ImprovementPercentages)/100.
The full calculation for ASpd is ASpd = [200 - SpeedMods * (WeaponDelay - ([WeaponDelay*Agi/25] + [WeaponDelay*Dex/100])/10)].
You can calculate your Swings/Minute as 60/(Delay/50). This is because each point of Weapon Delay is equal to 1 frame on the screen. There are 50 frames per second and of course 60 seconds per minute. This can be further simplified to 3000/Delay.
Swings/Minute is actually a more accurate representation of attack speed than ASpd.
See the bottom of this page for the table of Weapon Delays by class. In the case of Weapon Delays, the smaller the number, the faster!

Casting Time:

A hidden statistic. The rate at which a character can cast a skill.
The basic formula is ActualFrames = [BaseFrames*(150-Dex)/150].
In seconds, the formula is ActualSeconds = [BaseSeconds*50*(150-Dex)/150]/50.
For the amount of Dex required per frame use: 1/[BaseFrames/150].

HP:

HP stands for Hit Points or Health Points and is a measurement of how long you can sustain damage before you die.
HP is improved by your Base Level by an amount depending on your class. It is also improved by your VIT at a rate of 1% per point of VIT.
HP is calculated as [([(35 + BaseLevel*HPMultiplier + SigmaOfBaseLevel*HPFactor)*(1 + VIT/100)]+HPAdditions)*ItemHPMultipliers] where SigmaOfBaseLevel means adding up every integer from 2 to the BaseLevel of the character. As a simple example, at level 12 with 1 VIT, a Magician will have (35 + 12*5 + (2+3+4+5+6+7+8+9+10+11+12)*0.3)*(1+1/100) = (35 + 60 + 77*0.3)*1.01 = (35 + 60 + 23.1)*1.01 = 118.1*1.01 = 119 HPs.
Find the HP Multiplier and HP Factor in the table of Job Modifiers at the bottom of this page.
Items that give VIT bonuses (excepting cards!) give an HP Addition of the same size. eg. Necklaces give +2 Vit, so they also give 2 points of HP Addition.

HP Recovery:

A hidden substat. The rate at which a character recovers HPs.
The Juno formula for HP Recovery is HP Recovery Power = [([Vit/5] + [MaxHP/200])*RecoveryMods].
You recover HPs every 6 consecutive seconds while standing still.
You recover no HPs while moving.
Sitting halves the time required to recover HPs to 3 consecutive seconds.
You recover no HPs when carrying more than half your Weight capacity.

SP:

SP stands for Skill Points and is a measurement of how many skills and spells you can use before your abilities are exhausted.
SP is improved by your Base Level by an amount depending on your class. It is also improved by your INT at a rate of 1% per point of INT.
SP is calculated as [([(10 + BaseLevel*SPFactor)*(1 + INT/100)]+SPAdditions)*ItemSPMultipliers].
Find the SP Factor in the table of Job Modifers at the bottom of this page.
Items that give INT bonuses (excepting cards!) give an SP Addition of the same size. eg. Earrings give +2 Int, so they also give 2 points of SP Addition.

SP Recovery:

A hidden substat. The rate at which a character recovers SP.
The Juno formula for SP Recovery is SP Recovery Power = [[(1 + [Int/6] + [MaxSP/100])]*RecoveryMods].
If your Int is equal to or greater than 120, then you get bonus SP Recovery Power equal to [(Int - 120)/2]+4.
You recover SP every 8 seconds while standing and/or walking.
Sitting halves the time required to recover SP. The effect of the priest skill Magnificat also halves the time required to recover SP. If only one of the conditions is in effect, you will take only 4 seconds to recover SP. If both of the conditions are in effect, you will take a mere 2 seconds to recover SP.
You recover no SP when carrying more than half your Weight capacity.

Weight:

Weight is the measurement of your ability to carry stuff. This includes all in your inventory and that you have equipped. In addition, there is an absolute limit of 64 items that may be carried in your Inventory at once. If you unequip an item or open a Old Blue Box, Old Purple Box or Old Card Album and it would take you over the 64 item limit, the item is lost forever. Whatever you do, don't go anywhere near the 64 item limit! It's not worth doing something that will make you cry.
Weight is improved by Class and Base Str. Base Str is the left side only of the Str value. Weight is calculated as 2000 + WeightModifier + BaseStr*30.
Find the Weight Modifier in the table for Job Modifiers below.


Game Mechanics - Substats
While the 6 main attributes of Strength, Agility, Vitality, Intelligence, Dexterity and Luck are the ones you can directly improve, they don't actually directly improve your abilities in combat. Indeed, they improve your derived statistics (substats) and it is these that are directly used to determine combat effectiveness. Credits to RagnarokOptomiseProject and Mistress's Nest as sources for some of the information (you can never know everything or give enough credit).
Atk: Atk stands for Attack and gives an indication of how much damage you will do when you hit something. The visible components of the Atk score are your Strength plus the Atk of the weapon you are using on the left and the damage bonus from any pluses the weapon might have on the right. The real value on the left of your Atk score includes hidden bonuses from Strength, Dexterity and Luck. For fists, the true value is equal to: STR + [STR/10]^2 + [DEX/5] + [LUK/5] where [] indicates you round the value inside down before continuing and ^2 indicates squaring. For weapons, the true value is equal to: STR + [STR/10]^2 + [DEX/5] + [LUK/5] + WeaponAtk + AtkBonusCards where [] indicates you round the value inside down before continuing and ^2 indicates squaring. For missile weapons, the true value is equal to: DEX + [DEX/10]^2 + [STR/5] + [LUK/5] + WeaponAtk + AtkBonusCards where [] indicates you round the value inside down before continuing and ^2 indicates squaring. Not counting the value of WeaponAtk and AtkBonusCards, this true value is often referred to as the base damage. This base damage is basically the your Atk with bare fists. MAtk: MAtk means Magic Attack and gives an indication of how much damage a spell will do when cast against something. MAtk comes in two parts. The left-hand number is referred to as Min MAtk or Minimum Magic Attack. The right-hand number is referred to as Max MAtk or Maximum Magic Attack. Any time you use a magical attack, a random number between the Min Matk and Max Matk is generated and that number is used as the attack power (base damage) of every hit in that spell. Min MAtk is equal to INT + [INT/7]^2 where [] indicates you round the value inside down before continuing and ^2 indicates squaring. Max MAtk is equal to INT + [INT/5]^2 where [] indicates you round the value inside down before continuing and ^2 indicates squaring. Note that any weapon that gives a +15% bonus to MAtk does not change the number you can see in your status window, but is included in damage calculations. Hit: Hit refers to your ability to hit a target. It is the opposite of Flee. Each point of Hit increases your ability to hit a target by 1%. Your Hit is a combination of your Base Level, Dexterity and any special Hit increasing cards you may have equipped. It is calculated as BaseLevel + DEX + Cards. The Mummy card when put in a weapon you are wielding increases your Hit by 20. This is effectively the same as the description which says your Hit is increased by 20%. Critical: Critical is your chance of striking a critical blow against a target. Each point of Critical increases your ability to cause a critical by 1%. Your Critical on the Status window is equal to 1 + [LUK/3] + Critical Increasing Cards where [] indicates you round the value inside down before continuing. Your true Critical value is equal to 1 + LUK0.3 + Critical Increasing Cards. There is a special rule for Katar wielding Assassins. They get twice the Critical number they should do. Criticals are checked for before seeing if your Hit overcomes the targets Flee. So you can actually land a Critical even if you would ordinarily have no chance of hitting at all! Monsters have Luk too! Your chance of getting a critical against a monster is reduced by MonsterLuk/5. This reduction takes place after the doubling of Criticals for Katars and the Counter Attack skill. The full formula for Criticals at the time of a swing is equal to (1 + YourLUK0.3 + Critical Increasing Cards)CritModifier - TargetLUK/5. A Critical hit always hits for maximum damage and ignores Def. You can tell a critical has landed by the big red spiky bubble around the damage message and a special hit sound reserved for critical hits. Def: Def means Defence and refers to your ability to reduce damage inflicted on you. The left-hand part of Def is derived from items of Armor (including any pluses on them) and reduces damage by a percentage. The true value of Armor DEF is BasicArmor + Refinements2/3. That is, you take the full amount of whatever it says in your armors descriptions and any armor adding cards, but only two-thirds of the pluses on your armor. eg. +6 Plate is actually worth 10 + 62/3 = 14 DEF. Use this "true value" The right-hand part of Def is derived from your VIT and reduces damage by that number of points after the left-hand part is applied. VIT Defense for Players is calculated as [VIT0.5] + rnd([VIT0.3], max([VIT0.3],[VIT^2/150]-1)) where [] indicates you round the value inside down before continuing and rnd(x,y) indicates that you use a random number between the values of x and y. If y is less than x, then it becomes equal to x. max(x,y) indicates you should take the greater of x and y. VIT Defense for Monsters is VIT + rnd(0,[VIT/20]^2-1) where [] indicates you round the value inside down before continuing and rnd(x,y) indicates that you use a random number between the values of x and y. In other words, a random number between 0 and your vit divided by 20 and rounded down, then squared minus 1. As an example, 63 vit would mean each hit does 0-8 less damage (determined randomly on each hit). Def can never reduce damage inflicted below 1 point. MDef: MDef means Magical Defense and refers to your ability to reduce magical damage inflicted on you. The left-hand part of MDef is derived from items of Armor (only the MDEF portions) and reduces damage by a percentage. The right-hand part of MDef is derived from your INT and reduces damage by that number of points after the left-hand part is applied. There is a hidden bonus of VIT/2 to this part of MDEF. MDef can never reduce damage inflicted below 1 point. Flee: Flee is a measurement of your ability to dodge attacks made on you. It is the opposite of Hit. The left-hand part of flee is derived from your Base Level, Agility and any Flee enhancing cards. It is calculated as BaseLevel + AGI + Cards. Every 1 point of the left-hand part of flee increases your probability of dodging by 1%. The minimum chance of dodging is 0% and the maximum chance is 95%. No matter what, a monster always has a chance of hitting you. It's kind of like a critical chance for monsters. The right-hand part of flee is derived from Luck. It is calculated as 1 + [LUK/10] where [] indicates you round the value inside down before continuing. Every 1 point of the right-hand part of flee gives you a 1% chance to get a "Lucky" dodge. This lucky dodge is calculated before the other kind of dodge and separately from it. Even if you had 0% chance to dodge based on the left-hand part of flee, a lucky dodge can still save you! ASpd: ASpd stands for Attack Speed and is a measurement of your ability to swing fast. ASpd is improved by your Job, the Weapon Speed of the Weapon/s you are wielding, your Agility and your Dexterity. ASpd is calculated as 200 - Delay. Delay is calculated as Delay = SpeedMods * (WeaponDelay - ([WeaponDelayAgi/25] + [WeaponDelayDex/100])/10). Delay should be rounded up to the nearest whole number. Speed Mods come from anything that gives a speed boost, such as potions, skills and special weapons. The benefits are cumulative. Formula for speed mods is (100-ImprovementPercentages)/100. The full calculation for ASpd is ASpd = [200 - SpeedMods * (WeaponDelay - ([WeaponDelayAgi/25] + [WeaponDelayDex/100])/10)]. You can calculate your Swings/Minute as 60/(Delay/50). This is because each point of Weapon Delay is equal to 1 frame on the screen. There are 50 frames per second and of course 60 seconds per minute. This can be further simplified to 3000/Delay. Swings/Minute is actually a more accurate representation of attack speed than ASpd. See the bottom of this page for the table of Weapon Delays by class. In the case of Weapon Delays, the smaller the number, the faster! Casting Time: A hidden statistic. The rate at which a character can cast a skill. The basic formula is ActualFrames = [BaseFrames(150-Dex)/150]. In seconds, the formula is ActualSeconds = [BaseSeconds50(150-Dex)/150]/50. For the amount of Dex required per frame use: 1/[BaseFrames/150]. HP: HP stands for Hit Points or Health Points and is a measurement of how long you can sustain damage before you die. HP is improved by your Base Level by an amount depending on your class. It is also improved by your VIT at a rate of 1% per point of VIT. HP is calculated as [([(35 + BaseLevelHPMultiplier + SigmaOfBaseLevelHPFactor)(1 + VIT/100)]+HPAdditions)ItemHPMultipliers] where SigmaOfBaseLevel means adding up every integer from 2 to the BaseLevel of the character. As a simple example, at level 12 with 1 VIT, a Magician will have (35 + 125 + (2+3+4+5+6+7+8+9+10+11+12)0.3)(1+1/100) = (35 + 60 + 770.3)1.01 = (35 + 60 + 23.1)1.01 = 118.11.01 = 119 HPs. Find the HP Multiplier and HP Factor in the table of Job Modifiers at the bottom of this page. Items that give VIT bonuses (excepting cards!) give an HP Addition of the same size. eg. Necklaces give +2 Vit, so they also give 2 points of HP Addition. HP Recovery: A hidden substat. The rate at which a character recovers HPs. The Juno formula for HP Recovery is HP Recovery Power = [([Vit/5] + [MaxHP/200])RecoveryMods]. You recover HPs every 6 consecutive seconds while standing still. You recover no HPs while moving. Sitting halves the time required to recover HPs to 3 consecutive seconds. You recover no HPs when carrying more than half your Weight capacity. SP: SP stands for Skill Points and is a measurement of how many skills and spells you can use before your abilities are exhausted. SP is improved by your Base Level by an amount depending on your class. It is also improved by your INT at a rate of 1% per point of INT. SP is calculated as [([(10 + BaseLevelSPFactor)(1 + INT/100)]+SPAdditions)ItemSPMultipliers]. Find the SP Factor in the table of Job Modifers at the bottom of this page. Items that give INT bonuses (excepting cards!) give an SP Addition of the same size. eg. Earrings give +2 Int, so they also give 2 points of SP Addition. SP Recovery: A hidden substat. The rate at which a character recovers SP. The Juno formula for SP Recovery is SP Recovery Power = [[(1 + [Int/6] + [MaxSP/100])]RecoveryMods]. If your Int is equal to or greater than 120, then you get bonus SP Recovery Power equal to [(Int - 120)/2]+4. You recover SP every 8 seconds while standing and/or walking. Sitting halves the time required to recover SP. The effect of the priest skill Magnificat also halves the time required to recover SP. If only one of the conditions is in effect, you will take only 4 seconds to recover SP. If both of the conditions are in effect, you will take a mere 2 seconds to recover SP. You recover no SP when carrying more than half your Weight capacity. Weight: Weight is the measurement of your ability to carry stuff. This includes all in your inventory and that you have equipped. In addition, there is an absolute limit of 64 items that may be carried in your Inventory at once. If you unequip an item or open a Old Blue Box, Old Purple Box or Old Card Album and it would take you over the 64 item limit, the item is lost forever. Whatever you do, don't go anywhere near the 64 item limit! It's not worth doing something that will make you cry. Weight is improved by Class and Base Str. Base Str is the left side only of the Str value. Weight is calculated as 2000 + WeightModifier + BaseStr30. Find the Weight Modifier in the table for Job Modifiers below.