Finns are not ostentatious and this is reflected in the dress code adopted in mainstream business circles in Finland. A wide variety of styles and levels of formality can be observed but everything is typified by a desire to be seen as unpretentious.
Men tend to wear sports jackets and trousers in offices and these are often in muted or pastel colours. Women will often wear trousers and again will be smart without being too 'flashy'.
Casual wear such as jeans and T-shirts can be found in many of the more hi-tech industries.
Be aware of the climatic changes in Finland. Take lots of layers of warm clothes in the winter - it's cold outside, but sometimes very hot in the office. Hats, scarves, gloves and rubber-soled shoes are advisable in the winter months.