What is the difference between uptime and efficiency?

Uptime is the share of scheduled hours the machines are worked; efficiency is how fast they earn standard hours while worked. A mill worked 8 of 10 hours at 90% of routing pace has 80% uptime and 90% efficiency.

Why is capacity in hours, not parts?

Because a job shop runs a mix of parts with different cycle times, so standard hours are the only common unit. For one part family, divide the hours by its standard hours per part.

What load should I plan to?

Below 100%, by a margin set from your own lead-time history. Queue time grows steeply as load nears capacity, so a fully booked shop quotes long lead times and cannot take rush work.

Where does the booked load come from?

From open orders in your ERP: standard setup plus run hours for every operation on this work center due in the window. Include released and firm orders; leave out quotes you have not won.

Contract Manufacturing, Job Shop Quoting & Make-to-Order calculator

Job Shop Capacity Calculator

Check whether a work center can take more RFQs or rush jobs in a planning window. You need machines, scheduled hours, uptime, efficiency, first-pass yield and the standard hours already booked.

What this calculator does

Hours of good work a job shop work center can deliver in a planning window, and how much your booked orders already use.

Formula used

Scheduled machine hours = machines × scheduled hours per machine
Rated capacity = scheduled machine hours × uptime × efficiency
Good-part capacity = rated capacity × first-pass yield
Booked load on capacity = booked load ÷ good-part capacity; open hours to sell = good-part capacity − booked load
Hours lost to downtime = scheduled machine hours × (1 − uptime)

Inputs explained

Machines in the Work Center: Interchangeable machines that can run the booked work.
Scheduled Hours per Machine: Staffed hours in the window: days × shifts × hours per shift.
Uptime: Hours worked, setups included, ÷ scheduled hours, from downtime logs.
Efficiency: Standard hours earned, scrapped parts included, ÷ hours worked, from job costing.
First-Pass Yield: Good parts ÷ parts started, from inspection or job records.
Booked Load: Standard setup and run hours of open orders due in the window.

How to use the result

Best suited to deciding whether to accept a rush order, setting quoted lead times for next month, justifying overtime or a second shift.
Pooled hours can hide an overloaded machine inside a total under 100%; check each constraint on its own. Does not sequence work: orders bunched early in the window can still miss dates.

Current U.S. benchmarks

The U.S. prime lending rate is 7.00% (Federal Reserve via FRED, 2026-10-02). Payback and financing math should start from today's rate, not a remembered one.

Common questions

What is the difference between uptime and efficiency? Uptime is the share of scheduled hours the machines are worked; efficiency is how fast they earn standard hours while worked. A mill worked 8 of 10 hours at 90% of routing pace has 80% uptime and 90% efficiency.
Why is capacity in hours, not parts? Because a job shop runs a mix of parts with different cycle times, so standard hours are the only common unit. For one part family, divide the hours by its standard hours per part.
What load should I plan to? Below 100%, by a margin set from your own lead-time history. Queue time grows steeply as load nears capacity, so a fully booked shop quotes long lead times and cannot take rush work.
Where does the booked load come from? From open orders in your ERP: standard setup plus run hours for every operation on this work center due in the window. Include released and firm orders; leave out quotes you have not won.

Related guides

Last reviewed 2026-10-01.