Combining OD&D Attack & Saving Throw Tables

Attack Matrix I annotated with the Saving Throw Categories

Above is a hypothetical format for combining two tables in OD&D: Attack Matrix I, which is used for PCs when they attack, and the Saving Throw Matrix. 

It's easy to do this because both rely on d20 rolls, and both tables advance the classes in the groups of levels (3 levels for Fighters, 4 levels for Clerics, 5 levels for Magic-Users). 

A 1st level fighter needs the same score (12) to Save Versus Poison as to hit AC 7, and the other saving throw categories likewise correspond to AC6 to AC3; i.e., Wands = AC6, Stone = AC5, Breath = AC4, Spell = AC3, as annotated above.

The higher levels match well enough. There is a bit of discrepancy in the spots where the Saving Throw table jumps differently. 

But a Fighter 10-12 saves 9/8/7/6/5 in the combined table versus 10/8/8/7/6 on the Saving Throw table. That's not more than a 5% difference between any two rolls.

In order to retain the relative saving throw bonus/penalties between classes, the following adjustments would also be used:

Magic-Users get a -1 to Poison, Wands and Breath, and a +1 to Stone at all levels, plus a +1 to Spells for each rank they are in (+1 at 1-5, +2 at 6-10, +3 at 11-15 etc). 

Clerics get a -1 to Spell & Breath, a +1 to Wands at all levels, and a +1 to Poison for each rank they are in (+1 at 1-4, +2 at 5-8, +3 at 9-12 etc).

This table can also be used to adjust the saving throw values. Poison by default would be AC7, but you could have weak poison (AC9) or a strong poison (AC5). One could also add a new easier category, like "Falling" at AC8, perhaps increasing the "AC" for every additional 10' fallen.

This is similar to using difficulty class (DC) values in 5E. To illustrate this, here is a further modified version with Descending AC replaced by Ascending AC/Difficulty Class:

Looking at OD&D in terms of 5E, one would view the saving throws in terms of Difficulty Class (DC), with Poison having a DC12, Wands having a DC13, Turned to Stone having a DC14, Dragon Breath having a DC15, and Spells having a DC16.

The table at the top of this post could also be used with Holmes Basic, which uses the OD&D tables, but with the addition of a Normal Man column prior to the Level 1-3 column (this was an addition to Holmes' manuscript by Gygax/TSR).

(Adapted from several posts in this recent thread in ODD74)