=IF(B1 < 1024;
    CONCATENATE(B1;" B");
    IF(B1 < 1048576;
        CONCATENATE(ROUND(B1 / 1024; 2); " KB");
        IF(B1 < 1073741824;
            CONCATENATE(ROUND(B1 / 1048576; 2); " MB");
            IF (B1 < 1099511627776;
                CONCATENATE(ROUND(B1 / 1073741824; 2); " GB");
                CONCATENATE(ROUND(B1 / 1099511627776; 2); " TB")
            )
        )
    )
)