Knowing How Much Work Your Shop Can Actually Take On

Published by
Throne of Profit Editorial

Reviewed by
William Hassell
Founder & Chief Editor, Throne of Profit

A customer asks when you can ship, and you give a number. It feels confident in the moment — three weeks, no problem — because the shop doesn't look full and you don't want to lose the job. Then the promised week arrives and the part is still sitting behind four other jobs on the same machine, and now you're making an apology call you didn't have to make.

That gap between what you promised and what the floor can actually produce almost never comes from laziness or bad machines. It comes from quoting lead times against a number in your head instead of against real, countable capacity. You can't promise a delivery date honestly until you know how many productive hours each machine and shift actually has available — not in theory, but after setups, maintenance, and the jobs already committed.

   WHAT "CAPACITY" ACTUALLY MEANS

   theoretical hours   ▇▇▇▇▇▇▇▇▇▇  (2 shifts × machine)
   minus downtime      ▇▇▇▇▇▇▇▇░░  (maintenance, breaks)
   minus setups        ▇▇▇▇▇▇░░░░  (changeover between jobs)
   minus committed      ▇▇░░░░░░░░  (jobs already promised)
                        └─ what's REALLY open to promise

Owner symptoms

• You quote lead times off a gut feel, then miss them often enough that customers have stopped trusting your dates.

• The shop looks like it has room, but jobs still stack up behind one or two machines.

• When a rush order comes in, you can't say whether you can take it without walking the floor and asking the operators.

Why this happens

Most small shops track what's been sold — the order book — but not what's available to sell. Capacity gets treated as one big pool ("we can handle it") when in reality it lives machine by machine and shift by shift. A job that needs the press brake doesn't care that the lathes are idle. Add in the hours that quietly disappear to setups, maintenance, and breaks, and the "40 hours a week per machine" in your head is often closer to 28 in practice. Without counting those losses, every lead time you quote is a hopeful guess.

Common mistakes

• Quoting against theoretical hours — treating a machine as available 40 hours when setups and downtime eat a third of that.

• Pooling capacity across dissimilar machines, so a bottleneck machine's true backlog stays hidden behind idle ones.

• Ignoring committed work already promised on the same equipment when you quote the next job.

• Forgetting the second shift is thinner — fewer operators, less coverage — and counting it as equal to the first.

• Never updating the numbers, so last quarter's assumptions drive this week's promises.

Business consequences

Overpromised lead times cost more than a late part. Each miss chips at the customer relationships you depend on for repeat work, and the scramble to recover — overtime, expedited freight, bumping another customer's job — quietly erodes the margin on the very order you rushed to win. Chronic misses train customers to pad their own timelines or shop elsewhere. The owner who measures real available capacity quotes fewer jobs but hits the dates, and a shop known for hitting dates can often charge for that reliability instead of apologizing for the lack of it.

How experienced operators think about it

They stop asking "are we busy?" and start asking "how many productive hours does this machine have open, this week and next?" Capacity, to them, is a per-machine, per-shift number they can actually count: available hours minus realistic setup and downtime losses, minus the hours already committed. They know which machine fills up first and treat its open hours as the real constraint on what they can promise. A lead time isn't a hope — it's a calculation against a number they trust.

Practical actions

1. List your work centers by machine or cell, not as one shop. Each is its own capacity bucket with its own backlog.

2. Count real available hours per shift, then subtract typical setup, maintenance, and break time to get productive hours — the honest figure is usually well below the theoretical one.

3. Load committed jobs against each machine so you can see, at a glance, which centers are booked out how far.

4. Quote lead times against the tightest machine a job needs, not against the shop's overall feeling of busyness.

5. Update the numbers weekly. Capacity moves as jobs finish and new ones land; a stale picture produces stale promises.

Questions every owner should ask

• If a customer asked right now, could I say which machine is booked furthest out — without walking the floor?

• How many productive hours does each machine really have once setups and downtime are subtracted?

• Are the lead times I quote based on counted capacity, or on not wanting to say no?

Frequently asked questions

Do I need scheduling software to do this?
No. Plenty of reliable shops run this on a whiteboard or a spreadsheet. What matters isn't the tool — it's that you're tracking available productive hours per machine and per shift, subtracting what's already committed, and quoting against the tightest constraint. Software helps once the volume gets high, but the discipline of counting real capacity is what fixes overpromising, and you can start that today with what you already have.

How do I know how much time setups and downtime actually eat?
Start by timing a handful of typical changeovers and noting the maintenance and break time on a normal day. You don't need precision to start — even a rough, honest subtraction from theoretical hours will put your quotes closer to reality than a raw machine-hours number does. Refine the figures as you go; the point is to stop pretending a machine is available for hours it clearly isn't.

Related articles

• Running a Profitable Small or Midsize Manufacturing Business — the pillar.

• Finding the One Machine That Sets Your Whole Pace — where your capacity really gets decided.

• Cutting Setup and Changeover Time Between Jobs — reclaiming the hours setups eat.

• Why Jobs Take Longer Than You Quoted — the general estimating problem.

• Where Time Leaks on a Typical Job — the hidden hours that break your dates.

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