How to tell a fertile egg

[Dwel1234]

Evening all
As you’ll be able to tell, I am very new to incubating/hatching birds. We’ve had hens for just over a year but bought a cockerel for the first time last week
He is a young bird and I don’t think has mated yet with any of the hens.
Does anyone have any foolproof way of checking fertility in eggs? I’m struggling to see the difference on the photos online of the white spot in an unfertilised vs fertilised
These are the eggs I have cracked tonight whilst making tea which I guess are all unfertilised. What differences am I looking for in fertilised eggs?

 

[MGG]

Evening all
As you’ll be able to tell, I am very new to incubating/hatching birds. We’ve had hens for just over a year but bought a cockerel for the first time last week
He is a young bird and I don’t think has mated yet with any of the hens.
Does anyone have any foolproof way of checking fertility in eggs? I’m struggling to see the difference on the photos online of the white spot in an unfertilised vs fertilised
These are the eggs I have cracked tonight whilst making tea which I guess are all unfertilised. What differences am I looking for in fertilised eggs?
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Neither of those look fertile. We'll be able to tell you if they're fertile or not. How old is this rooster? Have you seen him mount them at all? You could incubate some, and ideally if they're fertile they'll develop, but if you can't have more chicks best not to do that.