The following table is at the heart of the Fudge-M magic system.
Add the Power of the spell (the spell-caster's POW, unless the spell-caster is choosing to use a lesser amount) to the Levels of casting time to yield the spell-points of the spell. Divide the spell points between levels of duration and levels of area to determine how long the spell lasts and how big an area it covers. The difficulty of the spell is the spell-points of the spell. (As with all tasks in FUDGE-M, if the character has skill >= the difficulty, there is no need to roll.
If the spell is one that deals damage to the target, the caster may choose whether all the damage is dealt in an instant or whether it's spread out over the full duration of the spell; in no case does it do more damage than the POW of the spell allows, no matter how long the duration of the spell. On the other hand, if the spell is one that causes damage only in an area (e.g. a wall of fire) the spell will damage anyone who enters the area and will continue to do full damage each round the target remains in the area. To center an area affect spell on a particular target requires an opposed skill roll (Use Power vs. Agility) in addition to the casting roll, and the target may use a saved action (or abort) to get out of the way (see the combat rules for more details).
Example 1: A caster with POW 5 decides to cast a full-power spell that takes a full round to cast; the difficulty he needs to meet or beat with his skill to get the spell off is 6 (5 POW + 1 round casting). He decides to have the spell affect a single man-sized target (1 point), leaving 5 points for duration. The effects of the spell will last one hour. If he had cast it on himself, the area would be 0, so there would be 6 points of duration, or until the next twilight. If the spell deals damage to the target, increased duration just means the damage occurs little-by-little over the course of the spell (this might be appropriate for something like a poison or sickness spell).
Example 2: A caster with POW 4 decides to take an hour to cast
a spell; this yields a difficulty 9 (4 POW + 5 Duration) spell.
The spell can cover a single man-sized target for a week, or as an area
far as a bird can travel in a round
| Level | Duration/Casting Time | Area Radius |
| 0 | Instant | Self |
| 1 | 1 round (~3 seconds) | 1 man-sized target/touching |
| 2 | 1 melee | 1 meter/hex |
| 3 | 1 minute | As far as a man can jump |
| 4 | 10 minutes | 1/2 move |
| 5 | 1 hour | Full move |
| 6 | Until next twilight | Sprint |
| 7 | 1 day | Gallop |
| 8 | 1 week | an entire melee |
| 9 | 1 month | a single large building such a castle or cathedral |
| 10 | 1 season | an entire street |
| 11 | 1 year | a village |
| 12 | 1 decade | a medium-sized town |
| 13 | 1 generation (~ 4 decades) | City/wood |
| 14 | 1 century | Forest/region (e.g. Farmhold or County) |
| 15 | 1 millenium | Large Region (e.g. Theinhold or State) |
| 16 | 1 Age | Country |
| 17 | 1 Epoch | Sub-continent |
| 18 | 1 Period | Continent |
| 19 | 1 Aeon | World |
| 20 | Until the end of the world | 1 A.U. |
| 21 | Until the sun grows cold | 1 solar system |
| 22 | Until the galaxy is no more | 1 galaxy |
| 23 | Until the end of time | The Universe |
The idea behind using this chart is to have spells have a more organic, or fairy-tale, flavor, while still being mechanically easy to adjudicate. That's why instead of having each step be some multiple or exponential of a fixed amount of time, they are divided more arbitrarily, but in units that make a description of the mechanics of the spell (affects one person until the next twilight) sound more like a story in the genre. On the other hand, practicality beats purity, so certain game-mechanics terms (round, 1/2 move) do appear where it makes things easier on the GM.