Ok. How to calculate how much you might lose? Or probably better way to put it... Where to place your stop-loss.
That depends. You have to believe in what you're trading, than you have to know your strategy, how to execute it properly, your account size, margins, what exactly are your broker rules regarding positions and margins, and know what position size you're comfortable trading so that the swings don't cause you to make emotional decisions and also what trading style works best for you I think that covers the basics, start there once you have all of that, than you should be able to figure out an appropriate stop.
I went ahead and entered another bullish position a couple minutes before the news release. I went long on USD/JPY. Here's the results. The release was at 8:30. I realized that the 30-60 second delay it takes me to get the news is way too long to react as quickly as the market. I got the news from the Forex app's economic calendar but was initially unsure what to make of it. Unemployment was 3.6% vs 3.5% expected. But 225,000 jobs were added vs 165,000 expected. It took me a few long seconds to think about whether this report was good or bad. I came to the conclusion that it was good because the new jobs added were such a high surprise vs negligible rise in unemployment (that I'm now reading is actually a result of more people entering workforce, which is also bullish). So by the time I get back to my USD/JPY, I am way in the red. How could this be? Despite the fact that I guessed correctly, I still lost money. Then I looked closer at the chart, and I see that it spiked up immediately after the report before going down. If I had a take-profit in place, I would have profited.
You can see the same type of reaction looking at the ES chart. I verified that it was a reaction to the data release by looking at a 1 second chart (as oppose to leading up to the news release). And, btw here's a daily chart of the past 3 months of USD/JPY. Today's action is so small you can't even see it. And who knows what it actually the force moving the price. But I guarantee it isn't moving averages.
Ok. I now think this was the result of JPY doing well. Cause USD is up against most other pairs since the release. JPY is way up against every one I've checked so far. That's the problem with currencies. You have to bet in pairs. Is there a USD futures contract? DXY?
Bought right below H4 supply. Can break through any time but better to buy near demand. Google "Supply and demand trading" Supply/Demand thread here: https://www.forexfactory.com/showthread.php?t=390673
The best way to trade news announcements is to only trade when the results are a surprise i.e. way outside of analysts high/low expectations. There will be the initial jump and then price will retrace a bit (and very quickly) which will be your entry. The mistake is trying to get in on that first impulse move, and to also trade on news which is broadly in line with expectations. Might as well toss a coin for those ones