When calculating costs, consider how these factors may influence your budget:

• Age: Renovating a 100-year-old house may unearth unwelcome surprises (think: knob-and-tube wiring, asbestos, lead pipes, etc.).
• Size: Larger space = more money.
  
• Labor quality: Are you hiring a reputable contractor with insurance and credentials? Or a local handyperson who does side gigs?
  
• Complexity: It’s usually bigger bucks to bust down walls, re-arrange plumbing or electrical systems, or add an extension.
  
• Timeframe? If you plan to sell soon, your best bet may be smaller, less expensive improvements that will freshen up your house, such as painting or improving curb appeal, new trims, and moldings, or maybe even some new flooring. 
  
• DIY vs. hiring a contractor: “Do it yourself” can save money, but it also requires expertise, and extensive knowledge of building practices, tool purchases/ tool rentals and of coarse a considerable time commitment. 
  
• Fixtures/finish quality: A basic bathtub from Costco can cost as little as $400, whereas a Victoria and Albert clawfoot tub can run as high as $7,000.
  
• Other costs: Factor in designer/architect fees, building permits, costs associated with temporary relocation, appraisals, and a fund for emergencies. To be safe, experts advise to tack on between 10 to 25% on top of your budget to handle unexpected costs.