Physical job... how many calories burned?

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Hi There,
I have just started a job bagging and stacking fire wood. It is five hours a day after taking away lunch break. I want to make sure I am eating enought calories so I want to imput the amount I am burning. I bag and move approx 150 bags of firewood each bag contains approx 15 peices. Does anyone have any suggestions on how I can enter this? I don't want to change my daily activity level because this is only 4-5 days a week.
Thanks so much for any suggestions you can give.