Consilidated Size Rules

The following is a complation page containing all rules affected by size and notes concerning their importance and reasons. Use this only if you want to reference a complete document on size rules.

Size is very important, as creatures, spaceships and even robots, can get quite large. Characters, creatures, robots and vehicles all follow the same size charts for STR scores and BP. Use the following rules to determine variations in ability scores and derivative stats based on the relative size of the object.

Option: Size Multipliers

Before we begin with the recommended size system, let's look at the obvious option for determining size that demonstrates why the size scale system promoted further down should be preferred.

This option simply requires a multiplier. Roll up STR scores as normal, but apply a multiplier. If a person is twice as tall as a human, they have twice the strength and double the damage. If they are 10 times as tall, they have 10 times the strength and the damage is 10 times greater. You can also use decimals for more finite differences on the standard human scale. (1.0 is 5-5'11".) Twice human height is 2.0. (10-11'11".) Half human height is 0.5. (2.5-3'.) It is more elegant, but multiplication must be performed frequently. Though every weapon would be sized up or down to meet the character's needs in order to change the damage, otherwise the damage remains the same, and only the STR damage modifier would be multiplied by the size multiplier.

To calculate damage, apply the multiplier before rolling dice if the attacker is larger, or after rolling dice if the attacker is smaller.

It also gets a DEX modifier of 2 per whole multiplier regarding the difference in size. So if one creature is 5 times taller than another, it gets a -10 modifier to its attack and defend. Inversely, the opponent gets +10 to attack and defend.

    Example: If you have a size 0.3 unit up against a size 2.4 unit, the size 2.4 unit will have a STR and damage multiplier of 2.4 / 0.3 = 8 and have -16 DEX modifier. This means, if he uses a weapon causing 1D+3 damage and has a STR of 64, it will do 8D+24+16 damage if it is a hero, for a potential damage of 24-240 depending on resistance and critical hit, (assuming no critical resistance) with average damage (80) being more than enough to demolish almost any unit 1/8 its size.

    Inversely, the 0.3 unit will have a STR and damage multiplier of 1 / 8 = 0.125 and a +16 DEX modifier. This means, if he uses a weapon causing 1D+3 damage and has a STR of 64, it will do 1D+3+2 damage x 0.125 if a hero, for a potential damage of 0.375 to 3.75 (or 1-4 if a hero) depending on resistance and critical hit, (assuming no critical resistance) with average damage (1.25 or 2 if a hero) being barely enough to provide superficial wounds, but enough to do damage all the same.

The problem with this method is the amount of math required which breaks the system under its weight because it ends up eclipsing all other mechanics for time spent on it. However, the following method resolves all issues of math with an intuitive and easy-to-remember system. However, while somewhat gradual, it has an exponential growth by scale. It is broken down further into subssizes.


Subsize refers to a unit’s longest measurement, whether vertical or horizontal according to average human build. It can also be expressed by its overall circumference. In any case it is a general estimate, not exacting. If you believe the unit’s length does not accurately depict its mass and/or capabilities, you may adjust it up or down as you see fit with GM approval. Subsize is not the same as size, but is a sub-category of size.

STR has a special roll and bonus according to subsize. The subsizes given in parentheses represent the medium (size 2) size scale. The scores on this table adjust for the individual unit's variance within its species and exist in tandem with size scales. Size scales follow different rules. (See Size Scales and Magnitudes for various unit size differences.)

(Approx. Length/Height)
 2.1. Small (15” [1’3”]+)   1D   +10  2-3
 2.2. Diminutive (30” [2’6”]+)   2D   +20  4-5
 2.3. Short (45” [3’9”]+)   3D   +30  6-7
 2.4. Average (60” [5’]+)   4D   +40  8-9
 2.5. Tall (75” [6'3"]+)   5D   +50  10-11
 2.6. Very Tall (90” [7'6"]+)   6D   +60  12-13
 2.7. Large (105” [8'9"]+)   7D   +70  14-15
 2.8. Very Large (120” [10']+)   8D   +80  16-17
 2.9. Huge (135” [11'3"]+)   9D   +90  18-19

Note: There are no .0 subsizes. The entire previous size category represents the .0 subsize of the current size category, and is equal to every subsize of the current category and is thus one tenth of the category. For example, any size below 3.1 would represent 3.0. At the same time, 3.1 starting ability score roll starts at the point 3.0 would start in relation to 2.9. 3.0's roll would be 10D +100, which translates to 1D +10. The .0 subsize would normally be interpreted as 0D +0, but is eliminated because there is no such figure in a scale system for something that exists, as "0" is non-existence. However, it is simply handled on the previous scale as being below 1D +10 (or below 10D +100 on the lower scale).

Designer wrote:
This changes the human size STR roll from 5D +30 to 4D +40 for necessary scaling. This gives a 4.5 point (2.25 half score) improvement for average human-scale STR, starting from an additional 9 (4.5 half score) on the lower end to little to no improvement on the higher end, but I think you'll agree that this is not too much of a change. Note these differences:

5D +30 provides a range from 35 to 80 (17.5 to 40 half score) with a bell curve that is predominantly between 46 to 69 (23 to 34.5 half score), a mean area between 50 to 64 (25 to 32 half score) and an average roll of 57.5 (28.75 half score). Rolls of 35-45 and 70-80 won't usually be seen.

4D +40 provides a range from 44 to 80 (22 to 40 half score) with a bell curve that is predominantly between 51 to 73 (25.5 to 36.5 half score), a mean area between 54 to 70 (27 to 35 half score) and an average roll of 62 (31.5 half score). Rolls of 44-50 and 74-80 won't usually be seen.

I have confirmed these through many dice rolls. So 4D +40 provides a little longer curve than 5D +30, which is good for variety. This also puts to rest any thought of rerolling a die, because no matter what you roll, you will feel like you can accomplish something.

The Dwarf/Halfling range on the next size down is 33 to 60 (16.5 half score) with a typical mean of 45 to 50 (22.5 to 25 half score) and an average of 49.5 (24.75). Rolls of 33-36 and 57-60 won't usually be seen. Dwarfs get a bonus of +15 (+7.5 half score) instead of +10, which puts them down 3 points from the original rules.

Melee Score Rule Change

Both ranged and melee skill scores are based on DEX, rather than STR. STR provides a damage modifier to melee attacks as usual. The melee skill score no longer relies on STR at all.

Subsize Attack Modifiers

Units receive a penalty of -5 for attacking five subsizes down and +5 for attacking five subsizes up. For example, a Very Tall (2.6) unit gets -5 to attack a Small unit (2.1), while that Small unit gets +5 to attack the Very Tall unit, assuming the unit is within reach. The bonus/penalty does not apply to defense.

If the opponent is a full scale up or down, (from scale 2 to scale 1 or scale 3,) then the bonus/penalty increases to +/-10 per subsize on that scale. (Of course, critical successes ["00"] still cause damage if failure is all but guaranteed and critical failures ["99"] can't cause damage even if success is guaranteed otherwise.)

Size Scale or Magnitude

There are various size scales of unit. Size scales and magnitudes are the same. Units with an ability score determined on a different size scale than the character's actual size is known as "magnitude". Following are the size scales/magnitudes:

0. Miniature (Up to 1½")
1. Tiny (1½" to 1'2")
2. Medium (1'3"-11'5")
3. Giant (12.5'-124.9')
4. Massive (125'-1,249')
5. Colossal (1.25k'-12.49k')
6. Metropolitan (2.4 mi-23.6 mi)
7. Provincial (23.7 mi-236.4 mi)
8. Continental (236.5 mi- 2,365.4 mi)
9. Lunar (2,365.5 mi - 23,655.2 mi)
10. Planetary (23,655.3 mi - 236,552 mi)

Each one is a standardized step up from the previous, increasing or decreasing abilities and powers based on the character's size or equivalent. Anything below 0.1 is considered insect-sized, for which only swarming rules apply. All things derivative of STR and MOV, including BP, are calculated the same as for characters using the subsize system.


Each size scale or magnitude does ten times the damage of the previous scale or magnitude. So if a character with Massive STR fights a character with a Giant's BP, multiply the Massive character's damage by 10. So if it does 3 damage, it actually does up to 30 damage in a full hit on the next size down. (Characters can control how much damage they do up to the damage roll.)

The opposite occurs in the inverse. For example, when a Medium STR character does damage to a character with Giant BP, they do only 1/10 damage to the giant's BP.

For instance, a massive spaceship is clearly going to do a whole lot of damage to a motorcycle or character equivalent to 100 times character to character damage. Vaporization is likely.

Fractions that would be rounded up to doing only 1 damage on a unit the next size up would do only half a point of damage. Half damage applies only after adding another half damage.

When damage dice exceed 4D, you may bump the damage scale up to 1D/5 on the next magnitude.

    Example: Let's compare a dragon from p.48 of BBF to a dragon using this system. For a size 3.3 dragon, you roll 3 dice and add 30, for a range of 33-60 STR. That's 17-30 BP on the dragon's level, or 170-300 BP at character level. (Dragons are 240 BP in the BBF rulebook.) They still do 2Dx10 fire damage on the character level, as in BBF, but simply do 2D damage to another dragon or other creature on scale 3, that's 2-20 damage deducted from 17-60 BP. Instead of 10D, a bite would be 1D to another dragon. The claw is 6D (6-60) on the character scale, but could be adjudicated to 1D/2+1 (2-6) on the dragon scale. Tail Slap would be 1D/2 instead of 5D. If the dragon's stats are written out for dragon's scale, you would multiply it all by 10 (add a "0" to the end,) on the fly for the character's scale. Or you could write it all for the character scale with x10 already figured in. Now that you can do it with a creature we know, you can do it with a creature you make up, or a giant version of a smaller creature we know, or visa versa.

General Ability Magnitudes

STR is the most common ability to be adjusted as a greater power. (Supers, super cannons, etc.) Damage according to power level may be multiplied by 10 per magnitude even if the unit belongs in a smaller size scale. The use of magnitudes is strictly up to the GM's campaign.

Offensive Strike would be the typical ranged offensive super power. To have the OS of a Giant against Medium BP, multiply the damage by 10. To have the OS of a Massive character against a Medium BP character, multiply the damage by 100; against a Tiny BP, multiply the damage by 1,000.

Stealth and Perception

A unit gets +5 to stealth checks for each subsize down it is from those it is hiding from, and the unit gets +5 for each subsize down it is when performing perception checks to discover larger units. A unit gets -5 to stealth checks for each subsize up it is from those it is hiding from, and the unit gets -5 for each subsize up it is when performing perception checks to discover smaller units.


Equipment after character generation costs double every 2 subsizes up from 4 and is halved for every 2 subsizes down from 4, and multiplied by 10 for every full size scale up and divided by 10 for every full size scale down.


To determine common movement speed for other scales, multiply the listed subsize MOV rating by the number of size scales up times 10 or divide the listed subsize MOV rating by the number of size scales down times 10.

If using anything other than ambulatory movement, multiply the MOV rate by the following numbers, based upon propulsion, to determine maximum possible maneuverable speed.

 Petroleum Engine  x10 
 Jet Engine  x100 
 Ramjet  x1k 
 Chemical Drive  x10k 
 Pulse Drive  x100k 
 Warp Drive  x1M