In my imaginary world the main character's country has fallen and they now live as slaves. The conquering country is cruel, and treat the slaves so badly that basically everything that they do to the slaves is crimes against humanity. They will kill the slaves if they do anything unsatisfactory. The conquerers feed them one meal every other day, and only just enough to keep them alive.

In this lifestyle, how many hours can these slaves possibly work a day to survive? How many hours would they have of sleep? Remember, the conquerers only give enough to keep the slaves barely alive.

(Edit:The reason why the oppressors are oppressing is because they want a workforce, and also are punishing the slaves for past wars.)

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    $\begingroup$ How long are these slaves supposed to last? $\endgroup$
    – Erik
    Commented Feb 26, 2018 at 20:26
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    $\begingroup$ The british famously found out in india that slaves that are under nourished can't work, their bodies just can't support the effort. Slaves often needed to eat more than their owners/overseers since they where doing hard labor. $\endgroup$
    – John
    Commented Oct 15, 2018 at 14:01
  • $\begingroup$ The ability of your slaves to provide useful work is directly proportional to how well fed, motivated and healthy they are. More than that - slaves aren't more profitable than paid workforce. If your "evil ruler" wants to get those big bucks, he will have to make then happy, healthy and well fed instead - and maybe consider freeing them and making them paid workers. Misery doesn't generate money, but happiness does. $\endgroup$
    – Mermaker
    Commented Oct 15, 2018 at 19:50
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    $\begingroup$ To add to @John 's idea, maybe some kind of processed sludge bar that gives them all the nutrients they need, but tastes terrible. Mental effects of food deprivation, with none of the physiological ones. $\endgroup$ Commented Oct 16, 2018 at 4:07
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    $\begingroup$ @SydneySleeper sadly some US prisons already do something like this, Nutraloaf, AKA Grue AKA a blended puree of meat byproduct and vegetable baked into a solid block. which has actually caused many lawsuits considering it cruel and unusual punishment. $\endgroup$
    – John
    Commented Oct 16, 2018 at 16:32

7 Answers 7


My great grandfather was a survivor of the soviet gulags, in his various stories about how bad it was he often stated that they could be worked as much as 14-16 hours a day. Thing is, the gulags goal wasn't really economic profit so much as extermination of undesirables through labor and starvation. What you describe in your setting isn't really slavery so much as genocide. In situations where the captors goals are profit they typically take better care of their slaves, since a beaten and starving wretch cant really accomplish much of any real value and is prone to revolt and acts of sabotage.


The labor force collapses in a few months

If calories in equals calories out, then a person stays the same weight. If calories ingested are less than calories expended then a person's weight will decrease over time. This is standard weight loss. Preferentially, the body will use carbs then protein then fat for fuel. Carbs would burn out in the first day or two. Muscle loss would begin almost immediately in all individuals.

The harder the slaves work, the faster they will burn out

Every human has a basal calorie requirement just to keep them alive. This covers thing like digestion, heartbeats, neural activity, etc. Let's assume a basal load of 1000 calories. Doing intense physical labor can easily add another 2000 calories to that requirement. Assuming people who aren't overweight, there's perhaps a few days of full intensity fat stores on a person. Without food though, the body quickly goes into starvation mode and calorie expenditure plummets.

How many hours a day they can work will depend on the task given to them. Heavy lifting won't last more than a few hours. Weaving or some other low intensity task will last longer.


They will sleep as much as they are allowed. Athletes are well aware of the body's need for rest when training heavily. These slaves are "training" far harder. Their bodies will want all the rest they can get.


There is another option, namely renting out your new slave labour and making the purchasers responsible for feeding them.

This used to happen in South Africa during the great depression with prisoners sentenced to hard labour. The labour was essentially 'sold' to farmers, quarries and the like, and they worked set (long) hours during the day. They were not fed much of a breakfast, nor much of a dinner, because these were provided by the prison. The person renting the labour on the other hand was required to provide them a lunch with a minimum set size and nutritional standard, and this was how the prisoners were sustained.

Prisoners who were not capable of hard labour were often only given light duties in the prison itself because their food allocations were not enough to sustain a heavy workload.

Ultimately, slave labour of any kind is a bad idea, not just because of the humanitarian aspect but because of the economics of it all.

Slaves (if they are to be sustained) require regular good quality food as they are doing physical labour. They require good medical care, and they require security. After all, slaves are highly unlikely to be happy with their lot, and will try to escape and/or kill their masters. In a more modern world, motivation is understood to be a critical element of productivity, and slaves just don't have any to remain in their state.

Even the Romans understood this with their practice of freeing accomplished Gladiators. They weren't accepted into society as such, but as a slave forced to fight for survival, the lure of freedom could be a compelling motivation to fight well and survive for another day.

Also, if your society has access to mechanisation, slaves as a workforce simply can't compete. There's a reason you don't drive past a farm these days and see hundreds of men cutting down sugar cane. A harvester does the job faster, and requires only a single skilled worker. And, the harvester requires less maintenance than a hundred human bodies and the only security you need for it is a lock on your barn door and the keys being put in the farm house.

Let's say though that this is just a mechanism to inflict pain on your enemy to appease your hatred. In such a case, others have provided sufficient answers as to how long your slave workforce would last, which isn't long with a single low quality meal in six being provided. You'd be far better off financially putting them all in an arena and letting them fight to the death; you'd be able to sell tickets to that and it only takes a single meal per slave to support.

NB. Don't try this at home. Slavery is still a horrific and barbarous action and should be opposed by every reasonable person. And remember, if hatred persists, see your therapist.

  • $\begingroup$ "There's a reason you don't drive past a farm these days and see hundreds of men cutting down sugar cane." That's a bad example. In most of the world that's exactly what you see. Sugar cane cultivation is largely unmechanized around the world. $\endgroup$ Commented Oct 17, 2018 at 15:16

It depends on what kind of labour your slaves are doing, but in most cases, sun-up to sun-down, however long that is in the current season (unless, of course, if your world has 600 hour per day or something wacky like that). That was the case for most agricultural labour (which is the type most slaves where used for historically) because artificial light is expensive and difficult to obtain and it also happens to coincide with a few things like how much time you need to spend working in the fields by season (winter for the most part requiring little work and spring, summer and autumn requiring quite a lot). "However long the sun is up" is also really easy to time and is about how long people can work continuously and comfortably. This is also the case for any delicate work that requires good lighting (i.e. manufacturing, textiles and construction for more obvious reasons).

For mining, it's a different story. However, the entire group of miners will probably be expected to work all day in shifts if they are doing deep shaft mining, simply because having the equipment (which is probably much more expensive than the slaves) sitting around for half the time is uneconomical. Lighting will have to be artificial anyway, so that is not a concern. However, continuous work in a deep shaft mine WILL kill the worker. It's just too hot, dusty, heavy and cramped for pretty much any human to last very long, so the workers would be given regular breaks at reasonable intervals.

If you want a more explicit number, then 16 hours is the longest working day I know that happened historically, in Victorian sweatshops.

Most of the time the slaves aren't working, they would be sleeping. It's not like they have much else to do. Though quality of sleep is a different matter, I know I would not be able to get much good shut-eye in a prison camp.

Two final points which, while not directly related to your question, might be worth thinking about:

  1. Remember to take into account any magic/science that may exist. For instance, if healing magic is something that can be done cheaply, it's possible that the slaves would be made to do gruelling, back-breaking work, be immediately healed, and then just thrown back to the pits to do it all again.

  2. Starving your workforce to the brink of death is never a good idea, even if they are slaves. It's normally only done to be super evil (Mwah hah ha!). Not only does it stop them from really doing any meaningful work, it also takes away one of the best ways you have for controlling your population, namely the distribution of food. Feeding your slaves properly not only allows them to work harder, but it also allows you to punish dissidents by starving them and reward collaborators and grasses by giving them spare gruel. It can also turn slaves against each other and prevent any organised uprising.

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    $\begingroup$ You do mean Victorian sweat shops (and not sweet shops), right? Although I suppose somebody's got to make all those toffees and lollipops... $\endgroup$ Commented Feb 26, 2018 at 21:03
  • $\begingroup$ i did ineed mean sweat yes. $\endgroup$
    – Ummdustry
    Commented Mar 1, 2018 at 14:56

Just to elaborate on the already great answers here:

The Nazi Concentration Camps were very similiar to what you described. In the german Wikipedia the average schedule for a day is described like this:

-4:00 /5:00 Wake up (summer/winter)

-5:15 1st counting of the prisoners

-6:00–12:00 Work

-12:00–13:00 Lunch (including march towards the food counters)

-13:00–18:30 Work

-19:00 2nd counting of the prisoners

-20:45 Return to the sleeping quarters

-21:00 Lights out

This amounts to about 12 hours of work per day. As @Green already pointed out the prisoners will deteriorate quickly. They won't be able to work fast or can do anything that needs more than basic thinking. They will not be an effective workforce but die rather quickly especially when diseases begin to spread which is rather probable.


A 2018 Human Rights Watch report documents exploited workers and slaves in fishing industry in Thailand working around 16 hours, with tasks like net repair sometimes meaning that crews work non-stop for periods exceeding 24 hrs.



Cost and Supply

One variable that may influence if the captors will make the slaves work to the point that they will collapse and/or die is how easy and fast is to get new slaves (supply) and how expensive it is (cost).

Brazil had one of the worst kind of plantations to work on, Sugar Cane, where there was so many different ways to die that the life expectations was much worst that in other places. That's why Brazil/Portugal were responsible for 40% of the slaves in America. Around 5 million were brought to Brazil compare to 400.000 to US.

The reason

The they keep slaves as the base of their economy or as some kind of punishment for the loser of the war?

If it's about money, than you are going to feed them enough so they can do the work more efficiently. If it's about torture, than you will give the bare minimum to keep than alive, but also wont push than to much so they die.

The kind of work

As mentioned above, the amount of hours will depend on what they are forced to do. If they are forced to develop computer games or work in advertise industry you can easily make they work 16 to 18 hours a day. If they have to break rocks in the sun, than I don't think anyone can last that much.


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