Reasons why you can't know your APR (Annual Percentage Rate) or staking Reward before you stake. Firstly, APR as a reward measurement is wrong based on the Corechain Protocol. The Core protocol distributes rewards daily, not yearly, but you still can't know your reward beforehand. The general reason is that nothing is fixed between Validators and Delegators on the Core chain. You have the power to make frequent changes based on your choice anytime, and the system can't predict your next move. Specific Reasons are, 👉 Rewards are not fixed on the Corechain. That is, the rewards Validators receive are not the same for each day because the source of reward which is transaction fees changes according to the number of transaction in a day, and Block production rewards also changes according to how many times a validator had the chance to validate transactions. 👉 Validators don't have the same number of Delegators under them each day and the system can't tell how many numbers of delegators will register under a validator, so the system can't share rewards without knowing the number of delegators under a validator. 👉 Validator commission is not fixed. A validator may decide to change his commission to woo more delegators at every round because the number of delegators under a validator is how they are elected for block production. So the system can't tell what a Validator reward will be in the next round and the staking reward cannot be calculated beforehand. 👉 A delegator may decide to change validators regularly based on regular increased or decreased validator commissions to leverage their daily rewards. The system can't tell what action a delegator may take next and which validator he may decide to pitch under in the next round. 👉 Delegators' stakes are not fixed and you know your rewards are calculated according to the size of your stake. A delegator may decide to increase or reduce his/her staking size as the need arises. The system can't tell you your next move, hence your reward cannot be calculated beforehand. 👉 A Jailed Validator may impede your reward production and the system can't tell which validator will be jailed next to accurately calculate your reward. A case study is Renec staking. Renec uses DPOS like the COREChain and their APR section has no reward percentage till today because of the freedom of changes you can make at any time, which the system cannot predict. In conclusion, because all activities on the chain vary according to Validators' and Delegators' interests (choice), the system can't tell your choices before you make them, and hence can't calculate your rewards before you stake them. You can only know your reward at the end of every 24 hours of your staking, which is when rewards are distributed. You can add more if you know. Thanks for reading through...😁