Here are some common equivalents when converting International recipes.

250 degrees F = 130 degrees C or Gas mark 1/2
275 degrees F = 140 degrees C or Gas mark 1
300 degrees F = 150 degrees C or Gas mark 2
325 degrees F = 160 degrees C or Gas mark 3
350 degrees F = 180 degrees C or Gas mark 4
375 degrees F = 190 degrees C or Gas mark 5
400 degrees F = 200 degrees C or Gas mark 6
425 degrees F = 220 degrees C or Gas mark 7
450 degrees F = 230 degrees C or Gas mark 8