How to calculate the required concentration for sodium sulfite to remove oxygen as an oxygen scavenger from a solution?

If I know the amount of oxygen in such a solution, how can I know the required concentration of sodium sulfite to be used and react as oxygen scavenger?

From the equation $\ce{2SO3^{2-} + O2 -> 2SO4^{2-} }$ you could conclude that you need (at least) 2 moles of sodium sulfite $(\ce{Na2SO3})$ for each mole of oxygen in solution.