Don't always trust freight calculators because cost of shipping may vary approximately from -35% to +15% (for example popularity, loading competitiveness; how the carrier appreciates his work etc.)

Here are the reasons for that:

(it is not taken into account in shipping estimate)

1) Price reduction

a) lower up to -35% because of competency among carriers

b) additional load - a carrier fills left over room in his van with your load

c) empty run - a trip made by a carrier with no load on board. It mostly happens when a carrier makes a return trip and it can heavily affect the cost of your shipping in a decreasing way.

2) Price increase ( +15% higher because of a complicated order)

(it is not taken into account in shipping estimate)

a) Shipment after 6 p.m. and overnight

b) Shipment on weekends or national holidays

3) Waiting time (the time when a carrier is waiting to get loaded or unloaded)

Approximate cost  - first 15-20 min - free of charge (it is effective in most cases but not guaranteed. It all depends on the carrier's conditions), any next 30 min - about £4,5-5

4) Local jobs

Delivery within place of carrier's residence - about £50 within a radius of 35 ml.

Note! The shipping calculator does not take into account such shipment categories as (oversized cargo; vehicle shipment) in view of a big difference in specificity of them.