For a 2013 Honda Fit (GE8) on stock suspension, all trims use essentially the same stock spring rates, and the best available measured data says:
Front spring rate: ≈ 1.7 kg/mm ≈ 95 lb/in
Rear spring rate: ≈ 2.0 kg/mm ≈ 112 lb/in
These numbers come from owners who’ve had the OE springs measured or back–calculated them; Honda doesn’t publish spring rates in the service manual. A FitFreak thread cites 95 lb/in front, 112 lb/in rear for 2009+ Fit (GE8), which includes the 2013 model year.
So for your 2013 Fit base manual, you can safely work with:
Front: ~1.7 kg/mm (95 lb/in)
Rear: ~2.0 kg/mm (112 lb/in)
Thank you, John. I will make note of those numbers.