Image forming apparatus and image forming control method which calculates a remaining lifetime

An image forming apparatus having a fixing part fixing a toner image onto a recording medium by heating it, includes an ambient temperature predicting part predicting an ambient temperature from a fixing temperature rising period of time taken until the fixing part reaches a certain temperature; a member temperature predicting part predicting a member temperature of a member from the predicted ambient temperature and an operating state of the image forming apparatus; a cumulative-used-service-lifetime calculating part calculating a current cumulative used service lifetime from the predicted member temperature, the operating state of the image forming apparatus and an immediately preceding cumulative used service lifetime; a limit-of-usable-period-of-time calculating part calculating a limit of usable period of time by subtracting the calculated current cumulative used service lifetime from a service lifetime of the member; and a reporting part reporting the calculated limit of usable period of time.