Spell Damage

For any spell that deals damage, use the Spell Damage table to determine approximately how much damage is appropriate give the spell's level. The table assumes the spell deals half as much damage on a successful saving throw or a missed attack. If your spell doesn't deal damage on a successful save, you can increase the damage by 25 percent.

You can use different damage dice than the ones in the table if the average damage is about the same. For example, you could change a cantrip's damage from 1d10 (average 5.5) to 2d4 (average 5), reducing the maximum damage and making an average result more likely.

Healing Spells

You can also use the Spell Damage table to determine how many Hit Points a healing spell restores. A cantrip shouldn't provide healing.