Avg DPS is based on the Minimum Weapon Damage and Maximum Weapon Damage listed on a player's Character Sheet.

As of build 100:

The basic calculation for Min Damage and Max Damage appears to vary by some unknown factors that the Devs would probably be unwilling to share.

Melee Damage appears to increase with increasing STR, but varies to degree possibly by speed and 1-handedness or 2-handedness.
Ranged Damage appears to increase with increaseing AGI, but varies to degree possibly by speed and 2-handedness or eventually 1-handedness.
+DPS or +% to all Slashing/Piercing/Crushing Attacks appears to have a normal affect to the basic Min. and Max. Damages.

Applicable physical damage bonuses given by equipment and/or Self Buff and Passive skills are visible and accounted for are visible on the Character Sheet.

This is a guideline on how certain bonuses will ultimately effect a Character's Avg DPS and helps when trying to answer questions like:

"If I wear this ring that gives +2% to all Slashing Damage, how much more damage will I do?"

Increasing Base Damage

Weapon Damage can be increased my equiping items with attributes such as:

+ Damage per Second to Slashing/Piercing/Crushing/Melee/Ranged Attacks (depending on weapon wielded)
+% to all Slashing/Piercing/Crushing/Melee/Ranged Damage (depending on weapon wielded)

If we account for relevant damage modifiers:

For Single Weapons:

Avg DPS =

(

min dmg + max dmg

2 x Attk Spd

+ Bonus Weap. DPS

)

x (1 + % Bonus)

[2A]

For Dual Wielding:

Avg DPS =

(

(

min dmg 1 + max dmg 1 +

Bonus DPS 1

Attk Spd 1

)

x (1 + %Bonus 1) +

(

min dmg 2 + max dmg 2 +

Bonus DPS 2

Attk Spd 2

)

x (1 + %Bonus 2)

2 x (Attk Spd 1 + Attk Spd 2)

)

[2B]

The Dual Wielding equation is complicated for the simple fact that, it is possible to wield 2 different types of weapons.
For instance, you could be wielding a crushing weapon your main and a piercing weapon in your offhand. Each weapon could have their own damage levels, both could have bonuses that apply only to each type and/or both, and of course each weapon could have a different attack speed.

Example - Dual Wield, Increase Base Damage

This is probably best demonstrated using a Dual Wielding Fighter for an example:

From the Fighter's Character Sheet and Weapon information:

Main Weapon is a piercing weapon	Offhand Weapon is a Crushing weapon
Main Min Damage = 1000 and Main Max Damage = 2500	Offhand Min Damage = 1900 and Main Max Damage = 4300
Main Attack Speed = 0.38 seconds / attack	Offhand Attack Speed = 0.63 seconds / attack

Additionally, the Fighter has the following bonuses equiped:

+23 Damage per Second to All Piercing Attacks	+44 Damage per Second to All Crushing Attacks
+16 Damage per Second to All Crushing Attacks	+33 Damage per Second to All Slashing Attacks
+19 Damage per Second to All Melee Attacks	+3% to all Ranged Damage
+2% to all Melee Damage	+4% to all Piercing Damage
+37 to Melee Attack Rating

Right off the top one can eliminate any Slashing or Ranged bonus effects as this fighter is not wielding either type.
The Melee Attack Rating bonus can also be crossed off; while it is relevant, it has no direct effect to the damage.

Main Weapon - Piercing and Melee Bonuses apply

Offhand Weapon - Crushing and Melee Bonuses apply

The effects can now be tallied:

Main Weapon Bonus DPS = 23 + 19 = 42

Main Weapon %Bonus = 2% + 4% = 6%

Offhand Weapon Bonus DPS = 44 + 16 + 19 = 79

Offhand Weapon %Bonus = 2%

Pluggin the tallied values into equation [2B]:

Avg DPS =

(

(

1000 + 2500 +

42

0.38

)

x (1 + (6/100) ) +

(

1900 + 4300 +

79

0.63

)

x (1 + (2/100) )

2 x (0.38 + 0.63)

)

=

(

(	3500 +	110.5	)	x (1 + .06 ) +	(	6200 +	125.4	)	x (1 + .02 )

2 x (1.01)

)

=

(

(	3827.1 +	)	+	(	6451.9	)

2.02

)

Avg DPS =

5110.9

Rounding Errors

Fractional numbers in Dungeon Runners are represented as 8-bit fractions in logic calculations. There is a possibility that the calculations shown may not exactly match what will be displayed on the the Character Sheet.
There is an additional possibility that attack speeds may be (further) rounded due to animation and frame rate considerations.

See: Rounding Errors for more detailed information and sample calculation.

Revision history of Avg DPS - Increasing Base Damage