Depending on the nature of your seeds and kernels, that can be a complicated question. In the fine tradition of Dr Who's Tardis, it's bigger on the inside/smaller on the outside. Here are a couple of links that try and dissect the problems:
https://catacombs.space1999.net/main/cguide/umeaglescale.html
https://www.eagletransporter.com/forum/threads/real-eagle-scale-vs-r2-22-model-scale.162214/
If you have a particular kit in mind, it may be more useful to ask for the dimensions of that kit.
Cheers,
Colin