While it might be in the 1% range on a big jet, it's much more on smaller or medium jets. It's all very type specific. You strongly feel the drag on your performance, if you, say, should forget to retract the gear.
Some aircraft have very "aerodynamic" gears, while others nearly fall out of the skies. The type I'm flying e.g., has stronger performance penalties on medium flap setting than on the gear. What I gathered, the medium jets with their high leg gear struts have the biggest drag, like the A310, A320, B757. Smaller aircraft have smaller gears, and bigger aircraft have the same gear size with much bigger overall size.
Dani