"weigh it against" is correct and usable in written English.
It is used to mean to compare or evaluate two different things in order to make a decision. For example, "We must weigh it against our budget before deciding whether to buy the new machinery."
"You've got to weigh it against the costs.
If Mr. Obama's race had been a factor, they eventually had to weigh it against other concerns.
Examine the attacks, and weigh it against what you've learned about Mr. Edwards's qualifications as a vice president.
But look at the evidence, weigh it against the evidence that he died, and draw your own conclusions".
Then you weigh it against a raft of anti-homosexuality legislation that is coming into force in countries across the world.
Even Andrew checks his anger over life's blows, thinking, "It was all... a little much for one lifetime — though he had to weigh it against his socioeconomic privilege, health, maleness, whiteness, heterosexuality, American citizenship, etc., etc".
Mr. Obama takes what he says, weighs it against his own beliefs and possibly the opinions of many others, and then makes up his own mind.
"I am considering the possible impact of that violation and weighing it against the brutality of Mr. Valdez's admitted crime".
"You're willing to accept a certain risk if you're weighing it against something that's fatal," said Dr. Eugene Schiff, the director of the Center for Liver Diseases at the University of Miami School of Medicine.
She considers this future and weighs it against the alternatives — getting promoted to Casual Corner assistant store manager is a real possibility — and then, finally, nods.
Has he considered all that he has learnt about Wilkinson down the years and weighed it against the impressive evidence of enduring appetite and force that he has produced over the last few weeks, especially when finding the limits of England's possibilities in the recent psychological trial in Dublin?
