A supply-house run in the middle of a job costs 60–90 minutes: drive, counter line, drive back, re-setup. Two of those a week is a full workday a month burned on not having a $15 part. The fix isn't memory or discipline — it's the same reorder-point system every warehouse on earth runs, shrunk to a van shelf.
The three numbers that run the system
For every part you carry, know three things:
| Number | Meaning | Example: 45/5 cap |
|---|---|---|
| Quantity | What's on the truck right now | 2 |
| Minimum | The reorder point — hit it, order it | 1 |
| Order-up-to | Roughly 2× the minimum | back to 2 |
Setting minimums that fit how you actually work
- High-burn consumables (common caps, contactors, fuses, flame sensors): minimum = about one week of typical usage. If you go through two 45/5s a week, min 2.
- Big-ticket singles (motors, condensate pumps, control modules): carry 1, minimum 0. The rule that makes this work: the day it leaves the truck, it goes on the order. Not Friday. That day.
- Seasonal swing: in April, raise cap and contactor minimums; in October, raise igniters and flame sensors. Your truck should lean into the season before the season arrives.
The 10-minute weekly ritual
Friday afternoon or Monday morning, same time every week: open your restock list, order everything on it, done. The reorder-point system means you never audit the whole truck — the list built itself all week, one part at a time.
Why the whiteboard version fails
Whiteboards and mental notes fail at the exact moment they matter: end of a long job, hands full, next call waiting. The note doesn't get written, and three days later you're on a roof discovering the empty bin. A system only works if updating it costs less than one second at the moment of use.
The one-second version
That's the entire design brief behind our free Truck Inventory Manager: tap − when a part leaves the shelf — that's the whole interaction. Minimums are preset on the starter templates (tuned exactly as described above: consumables above their reorder point, big-ticket singles at min zero), the restock list assembles itself, and one button turns it into a cart. No login, no email, saves on your phone.
🚚 Open the Free Truck Inventory Manager →
No login. No email wall. Saves on your phone.
More free pro tools: the full 135-tool library — refrigerant charge, static pressure, capacitor testing, and troubleshooters for compressors, flame sensors, and gas valves.