Dairy farmers are expecting one of the worst pay-outs in 20 years.

Prices have slumped again, and Fonterra is expected to announce a cut to its forecast milk price on Friday.

Federated farmers South Canterbury chair Ryan O'Sullivan said that'll be more bad news.

He said he wouldn't think many farmers would be able to turn a profit this year, or break even for that matter.

"At that level of payout, there's going to be very few farmers who will actually turn a profit or manage to break even."

He believes farmers will probably receive one of the worst pay-outs in 20 years.

"The difference between the farmers' costs and the milk price - the margin there is probably one of the worst margins for 10 or 20 years."

But Otago dairy chief Steven Crawford said we could be jumping the gun.

He said we shouldn't be worrying too much about the current pay-out, when last season's pay-out is yet to be finalised.

Steven Crawford is advising farmers to worry about the things they can control, and to cut their losses where at all possible.

He said farmers can do that by minimising their inputs, and maximising their outputs.

"Minimising your inputs and maximising your outputs if its possible.. need to try and minimise the loss that may well be there at the farm gate."

Steven Crawford said monitoring spending is key.