My brick calculation says 2,300 bricks, contractor says 2,800. Who's right?

[Sri krishna]

I'm planning a small boundary wall project around my property and tried calculating the required bricks myself before requesting quotes.

The wall dimensions are approximately 30 ft long and 6 ft high. Based on my calculations, I came up with roughly 2,300 bricks. However, one contractor estimated around 2,800 bricks for the same project.

That's a difference of 500 bricks, which isn't insignificant when you're trying to budget materials.

I asked him why, and he mentioned mortar joints, breakage, cutting waste, and a few other factors that I hadn't considered.

For those with construction experience:

• How much variation is normal in brick estimates?
• Do contractors intentionally overestimate to be safe?
• Is there a reliable way to double-check brick quantity calculations before ordering?

I'd like to understand where the difference is coming from before I move forward.

Thanks!