Help me determine a fair equity split

I could use some advice on what % of equity to give away when taking small initial funding. The project I am working on is very labor intensive from a programming perspective.. should take around 500 hours of work which will be mostly done by me. I am trying to raise around $10k from friends to help with hiring people for things like design, and having some money left over for some small marketing campaigns. I'm wondering how some of you have split equity? Are there any common formulas? I was initially thinking of offering up 25% of the company for an investment of $10k. There is currently no product, just an idea and a plan. Thanks