What do fund commissions cost you?
A regular mutual fund plan pays a distributor commission every year through a higher expense ratio. A direct plan does not. Over time that small yearly gap compounds into real money.
How this is worked out
The direct plan grows at your expected rate; the regular plan grows at that rate minus the commission gap. The difference in their end values is the money the commission takes. The time figure is how much longer the regular plan needs to reach the same amount, computed with the same projection the app uses.
The default 0.8% gap is a typical equity regular-minus-direct expense difference; check your own scheme's two expense ratios and set the exact gap above. This is an estimate, not advice about any specific fund.
Synarsi does this continuously with your real numbers. See how it works.