Two designers can quote wildly different numbers for the same flat and both be fair: one charges by the hour, the other a percentage of your build. This calculator shows your likely design fee across all five models at once, so you can compare quotes like-for-like. It is the fee only, not the furniture, builders or materials.
Your project
Use the spread, not a single figure. The right model depends on how much hands-on management you want, not just the headline rate. For a full breakdown of what each model buys you, read our guide on how interior designers charge.