For a typical $500K seed round, here is my breakdown for 12 months of expenses. Feedback welcome.
2 founders + health insurance + taxes = $10k/month
2 engineers + health insurance + taxes = $20k/month
1 p/t designer = $5k/month
...and you've burned through $420,000 of your $500,000 in 12 months.
As for the other $80K?
Legal Fees: $10K (or $800/month); Space: $30K (depending on where...around $2500/month); Accounting/Finance: $10K ($800/month); Server Costs + Hardware: $12k ($1k/month); Miscellaneous Expenses including random contractors here and there, marketing expenses, SWAG, a party if you want, some travel to a few conferences, food, etc.: $18k ($1500/month)
Hope this helps.