Yes you can, however getting it light enough may be a higher ratio and be less expensive to go and buy the colour you want. You would be surprised how much white it would take to lighten an existing light colour and you might not get what you want.

Dear wife thought she was saving the environment by lightening 1gallon of a pale blue, she added 2 gallons before she saw a difference. Now I have 2 gallons of light blue, anyone need it?

ok, thanks! I didn't think of that. I certainly don't need two gallons or more of it.

To get to a "Linen White" you would add maybe a pint of the yellow to a gallon of white.

If you want to experiment, add the stronger color to the weaker color ... I make a small batch of 1/2 cup (4 tablespoons) of the white or lighter color and add 1 tablespoon at a time of the stronger color and test it.

If it only takes 1T to get the color I want, I know I need to add 1quart strong per gallon of white. 2T would be 2 quarts, 4T would be a 50:50 mix.

If 1T is too strong a color, I add another half-cup of the white and then my recipe becomes 1 pint of strong color for each tablespoon I used in the tester.

It's nice for ceilings to use a paler shade of the walls.

thanks for the mixing advice! I may actually try it to get rid of less than half empty cans of paint...