Technology • January 14, 2026
Factories are stuck in a never-ending cycle of overproducing and underproducing. On one hand, pumping out more product than needed ties up a ton of cash in inventory, and on the other, making too little leaves customers hanging. Imagine a factory chugging along at full speed on Monday, employees running overtime and equipment screaming in protest, only to be followed by a week of idle machinery and idle hands as you wait for demand to pick up again. This is the classic case of production gone haywire, generating waste, stress, and inefficiency galore. Heijunka is a lean approach designed to tame this rollercoaster and cut waste.
It was Toyota who first came up with the heijunka method all those years ago as a way to smooth out production flows and get rid of inefficiencies, and since then it has become a key part of the Toyota Production System. At its heart, Heijunka is about operating at a steady pace, one that perfectly matches up with what customers actually need. It’s not just a planning tool, but a whole way of thinking about how to run your operation.
In this article, we’re going to take a closer look at heijunka, how the heijunka box works, have a look at some real-life examples of how it’s been used, explore some of the key metrics like EPEI and takt time, and figure out just how to put heijunka into practice in your own business.
Heijunka is the systematic alignment of production type and volume over a specified period, designed to create a smooth and predictable manufacturing flow.
By leveling both the mix of products (product type) and the production quantity (volume), Heijunka enables manufacturers to optimize resource utilization, reduce waste, minimize inventory, and respond more flexibly to fluctuating customer demands. Unlike traditional batch production, which often leads to peaks and valleys in workload, Heijunka promotes continuous, balanced production, improving efficiency, quality, and overall operational stability.
Heijunka is a Japanese word that literally means “leveling” or “smoothing”. In the context of lean manufacturing, it’s about leveling out the production volume and type of production over a fixed period.
When we talk about “demand leveling” or “production leveling”, we’re really getting to the heart of what Heijunka is all about. It’s not about trying to keep up with every little surge in demand or using one-size-fits-all batch sizes. Heijunka is about producing at a steady average level that matches up with what customers actually need.
It’s a great way to cut down on overproduction, and instead of making loads of extra products just in case, you can produce customer orders based on actual demand.
Heijunka is a key part of the Toyota Production System (TPS), which was put together back in the mid-20th century by a team of clever engineers at Toyota.
At its heart, the TPS was all about sorting out the inefficiencies in traditional production methods and coming up with a system that’s flexible, efficient, and can adapt to changing customer preferences without overloading workers and machines.
The TPS has three main types of waste:
Heijunka is all about cutting down on these types of waste and getting rid of mura and muri by leveling out volume and product type. When production flow is steady, you don’t get those big spikes of work during peak periods and the downtime that comes with the lulls. It’s a much more efficient way to run your business.
To put heijunka into practice, you need to use a few specific techniques to level out production volume and sequence:
Leveling by volume means pumping out the same number of units over a set period. So instead of producing a lot of one product one day and almost nothing the next, you split the total production volume across all workdays — keeping the production workflow steady, preventing overloading and using production capacity to the max.
Example: A factory needs to produce 700 units of a product per week. Instead of producing 200 units one day and 50 the next, leveling by volume splits 700 units across all 7 working days with a daily target of 100 units. That keeps it consistent and slows down the risk of excess inventory.
When you’re producing multiple products, leveling by product becomes essential to avoid focusing too much on one product and neglecting the others. This technique keeps the production sequence balanced and prevents production bottlenecks from product variety imbalance getting out of control.
Example: A dairy plant producing milk, butter and ice cream can efficiently meet customer demands by determining the optimal production quantities of each product based on historical sales data. These quantities are then split into daily production schedule targets, so all product types are produced at the same level throughout the month.
The heijunka box or board divides production into weekly batches to meet customer demand. Each week, a production sequence is drawn up that matches demand which ensures:
EPEI (Every Part Every Interval) is a metric that shows how often each item is repeated in a leveled production schedule.
EPEI = The time it takes to do all changeovers / The time a day you’ve got to spend on changeovers
1. EPEI = number of days between production runs of the same part.2. The lower the number, the more frequent the production run of the part.3. The higher the number, the less frequent the production run of the part.
Calculation example: Lets say you make 6 different products, and each changeover takes you an hour:
EPEI = 6 / 3 = 2 days
This means it takes 2 days to fully produce all six products.
Why EPEI is Important? EPEI is a key indicator of how flexible your production line is. And the ultimate goal is to have really high flexibility and therefore really short time-to-market.
A lower EPEI means:
To get a low EPEI, changeovers need to be nice and quick. And this is where SMED (Single Minute Exchange of Die) comes in it takes changeover times down to single figures which means you can do volume and type leveling.
Heijunka is a lean method that works hand in hand with other lean manufacturing techniques:
How they work together:
In practice: the production leveling board contains kanban cards that are distributed to production cells according to the plan.
Using VSM:
When equipment stops because it’s detected a fault (jidoka), this can throw the heijunka rhythm right off. Solution
The heijunka production leveling board is actually a visualization tool, so you need to support it with 5S:
The heijunka box is a scheduling tool that shows the production order on the shop floor in a grid. Cards tell operators which orders to do next, creating a predictable workflow.
Modern lean manufacturing tools often replace the traditional production leveling board with digital tools to make sure production is as efficient as possible and to give everyone a clearer view of what’s going on.
A standard board is a table:
It is just a container for one or more master processes as a set of kanban cards, with each column corresponding to a time (like every 10 minutes)
Workflow: The materials handler shows up as scheduled.
Automotive factory example: The factory makes sedans (S), trucks (T), and vans (V) with the monthly demand split 50/30/20 for sedans, trucks and vans respectively.
Without heijunka: production is just a flat out sprint for 2 weeks on sedans, then a flat out sprint for 1.5 weeks on trucks, and finally a 1 week flat out sprint on vans.
With heijunka: Daily sequence: S-S-T-S-T-V-S-T-V-S
This mix is key for a few reasons:
Kanban and heijunka go hand-in-hand. We put the kanban cards into heijunka boxes according to the rhythm we’ve planned.
In stead of churning out one product in big batches, we’re churning out a whole range of products all at the same time with a tiny bit of downtime in between to switch things over.
Here’s what happens in each step:
By using a production leveling board for planning, you get a predictable workflow. The system works on a ‘pull’ principle — downstream processes ‘pull’ products via kanban signals, upstream processes only make items when instructed, and the production leveling board coordinates those signals to keep everything flowing smoothly.
Physical boards with cards work great for simple flows, but in complex situations with loads of different items, it starts to get a bit unwieldy.
Traditional heijunka systems are getting harder to manage these days — physical boards and cards need constant maintenance keeping track of card counts in cycles gets old, and with so many SKUs around it’s a right old headache.
Challenges of physical systems:
Digital planning tools offer:
Actions to take:
Tools you can use:
Group the products that:
Start by doing SMED—reducing production lot size is probably the most important thing when working with machines. Goal: Get setup times down to under 10 minutes (that’s how SMED got its name).
Methods for doing it:
Formula is: EPEI = (Number of products x changeover time) / available changeover time
Example:
EPEI = (10 x 8) / (480-400) = 80 / 80 = 1 day
Goal: get EPEI under 1-2 days for loads of flexibility.
Physical board:
Digital board:
Selection criteria:
Start with one product family:
KPIs to track:
Improvement cycles:
Automotive Industry
A company uses heijunka to produce different vehicle variants on a single line. Problem: Produce 5 car models with varying demand:
Heijunka Solution: Instead of weekly batches of each model, a repeating sequence is created, for example: A-A-B-A-C-B-D-A-B-C-E-A-B-D-A-C-B-A-E-D
This sequence:
Result:
Food Industry
A packaged food company was having trouble with seasonal fluctuations in demand. Their problem was:
Heijunka Strategy:
Results:
Traditional production planning usually means churning out really big batches of each product in turn (one of everything A, then one of everything B and so on). Heijunka is different — it creates a nice smooth mix of different products in much smaller batches, with changes happening all the time. This helps ease up the pressure on production, cuts down lead times, and basically helps businesses work the lean way. Often a heijunka box gets used to keep this schedule on track, helping teams keep up a good pace without over-producing. By leveling production according to the volume, you end up making products in sync with what the customers actually want, chopping waste and making things run a lot more efficiently.
Takt time is the pace at which you need to be making products to keep up with the demand from your customers. Heijunka builds on this idea — it takes takt time and uses it as the basis for its production planning: the average rate at which you produce is matched up with takt time, and the mix of products is based on what’s in demand. Leveling by volume makes for a nice balanced flow, and using a heijunka box or some other visual tool can help teams keep on top of the production schedule. This approach lets you be more confident in your production, and you can still make changes as the demand for products changes which is great for keeping things running smoothly and for those ongoing process optimization efforts.
Heijunka can create a bit of a buffer of finished goods to even out the ups and downs of demand, but in all honesty it dramatically cuts down on the amount of work-in-progress (WIP) and supplier stock you need to hold. In fact, all things considered you can expect to see a reduction in total stock across the whole supply chain of around 30-60%. When you combine heijunka with the lean manufacturing practices, it really helps keep production in line with what the customers are asking for, and you end up with a much more efficient setup which also minimizes stockpiling. This sort of thing is really good for those goals of ongoing process optimization because it makes it easy to spot and eliminate any waste in the production flow.
Yes, you can, but it’s a bit trickier. What you do is use ABC analysis — heijunka works best for high-volume A products (20% of the SKUs, but they account for 80% of the volume), while you can use some simpler campaigns for the medium- and slow-moving SKUs. Grouping products into families and using a heijunka box to help organize the production schedule can make things a lot easier. This way you can get a smooth flow of products even when you’ve got a really diverse range of products coming out and keep the whole thing aligned with what the customers are actually asking for and supporting those goals of continuous improvement.
Trying to implement heijunka in a small pilot project for just one product family will usually take 2-4 months — from start to launch and getting it all stable. Rolling it out right across the business can take a lot longer — 12-24 months in some cases. The key is to start small, get some results, and then scale up. If you do it bit by bit like that you can give employees time to get used to the new way of working, and it makes it a lot easier to maintain a good production plan and avoid batch production inefficiencies. In the end this approach supports lean manufacturing, continuous improvement, and basically gets the production side of things running smoothly and efficiently, and meeting the market needs while keeping the efficiency up.
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