This is an approximately conversion chart between gas mark and electric ovens.

Gas Mark	Fahrenheit	Celsius	Description
1/4	225	110	cool/slow
1/2	250	130	–
1	275	140	cool
2	300	150	–
3	325	170	very moderate
4	350	180	moderate
5	375	190	–
6	400	200	moderately hot
7	425	220	hot
8	450	230	–
9	475	240	very hot

This chart should be accurate enough for all your cooking needs, though keep in mind the temperatures will vary between different types, brands, sizes of ovens, in addition to your locations altitude, temperature, humidity, etc.