Why do my figures differ from the app I drive for?

Because they are answering different questions. The platform reports what it paid you. JoltMile reports what was left of it.

Three things come off between the two figures:

• Fuel for every mile you drove, including getting to your zone and home again. The platform pays you nothing for that drive and it still costs you.
• Insurance, spread across the driving it covers.
• Estimated tax, because you are self-employed and nobody has deducted it for you.

The gap is usually larger than drivers expect, and the commute is normally the biggest part of it. A 30-mile round trip to a depot for a six-hour block is 30 miles of fuel that earned nothing, on every single shift.

If you want the platform's own view for comparison, switch the headline rate to Before tax and expenses £/hr on your Earnings tab. That is gross earnings divided by hours, which is roughly what the apps advertise.