Haven't been playing Runescape recently... might come back to it eventually.

Magic Max Hit and Spell Cost Calculator

Magic Max Hit Calculator - this special calculator lists all the Magic Combat Spells along with their maximum hit and its casting cost. The calculator will automatically adjust the max hit and the cost of a spell based on the equipment you're wearing and other bonuses.

This calculator follows the Maximum Hit Formula provided on the official Runescape Wiki which states that nearly all spells have a fixed maximum hit which does not change as your magic level increases. The way to increase your maximum magic damage is by wearing special items and using potions which increase your Magic Damage: +x% stat

Max Hit Calculator

Magic Damage Boost: 0
Level Magic Spell Max Hit Spell Cost Runes needed