In cell G2 :
=(G1-$E$2<8)*$C$2+((MIN(G1;$F$2)-MAX(F1;$E$2-1))*$D$2/7)+(G1$F$2)*$C$2
to be pasted in H2, I2 and dragged downward as far as needed.
Regards.
Daniel

Aim: Calculate weekly cost of all equipment using mobilisation (mob),
demobilisation (demob) and weekly rates.

Source data: Mob and demob dates only.

My spreadsheet currently looks like below (Date format eg Xmas = 25-12-08).
Dates shown are for end of week (Friday). Costs tally up in columns G, H and
I.

A B C D E F
G H I
1 Equip $/Mob $/Demob $/Wk Mob Demob 31-10 07-11
14-11
2 EWP 100 100 700 29-10 13-11 400
700 700
3 Fork 100 100 700 05-11 10-11 0
400 400
4
Totals 400 1100 1100

G3 = $100/mob + 3 days (3/7 x $700 = $300) = $400 total

I am looking for a formula to insert into G2, H2, I2, G3, H3 and I3 to
achieve the results shown. Formula needs to reference date entries in E2,
F2, E3 and F3. Any help would be appreciated. Thanks.