This picture guide goes through the steps I take to boil the sap for making maple syrup. This is the second step in the process of making maple syrup, after collecting the sap, but before the final finishing boil.

If you buy through links on this site, I may earn an affiliate commission at no extra cost to you. 

Boiling maple sap into syrup is a fun and rewarding activity I like to engage in during the early springtime! In this article, I walk through the steps I use to make boiling sap as simple and straight-forward as possible.

For more FREE information on making Maple Syrup, visit the Maple Syrup Hub!

I go into a lot of specifics here, and of course you can modify any of these steps as necessary to fit your setup and style, but I find it is helpful to go into a lot of detail, especially for those who are just starting out, to have a baseline of what has worked for others, and what methods they have arrived at after doing it for years!

I hope this guide is useful to you!

Equipment I Recommend:

These are the supplies I use and recommend for sap boiling:

Using a refractometer changed my maple-syrup-making life! Not sure what a refractometer is, or how it is used for Maple Syrup? Check out this article on How to Use a Refractometer to Make Perfect Maple Syrup

Do you have A LOT OF SAP to boil down, or just need to speed up the process? If so, a regular propane burner may not boil down quickly enough for you. In that case I recommend a higher-capacity evaporator with a dual-burner setup.

How to Boil Maple Sap for Syrup – Step by Step

The following steps are the easiest way to boil maple sap to make your own maple syrup! The process is actually very straightforward.

You just need to boil the sap (which has a sugar content of ~1-3%) until most of the water has evaporated, and the sugar content in the remaining liquid is 66% (“maple syrup”).

You will end up with some really, really tasty maple syrup, and as you go along and gain experience, you may decide you want to tweak the process to your liking, but the method shown here is easy and “tried and true”!

Filtered maple syrup
Crystal Clear Maple Syrup!

I sometimes get the question, “Why don’t you just do all of the boiling on your kitchen stove?” The answer is that, while you could do this, it is generally avoided because of the large amounts of sticky steam that are generated in the sap-boiling process.

The other reason is that it takes several hours or more (depending on how much sap you are boiling down) and if you forget about it (and it boils all the way down) there could be a fire risk, which you would want to avoid inside your home!

The following method is the one that I used based on years of experience doing this with my family as a kid over a wood fire and continuing on now into adulthood.

I have refined my techniques over the years and in this post, I try to go through those techniques, and why I’ve arrived at that way of doing things!

Alright, let’s get started!

How to Boil Maple Syrup – General Overview of the Steps:

  1. Set up a turkey fryer or wood fire in a safe place.
  2. Fill a boiling pot with 5 gallons of sap.
  3. Boil the sap for approximately 4 hours.
  4. When you have about a half-gallon left in the pot, finish boiling on a stove.
  5. The syrup is done when it reaches 219°F or 66% sugar content.

Detailed Step by Step Procedure for Boiling Maple Syrup

Note: Click here to download a 1-page PDF "Maple Syrup Making Cheat Sheet" that contains a summarized version of all the steps to making delicious Maple Syrup!

Step 1: Arrange the Evaporator

Set up your wood fire or propane boiler in a safe place where it won’t start surrounding brush on fire.

I use a propane boiler (“turkey fryer”) mainly because of the ease of use (instant heat) and better tasting syrup.

Wood-burning can make syrup taste smoky, whereas propane burns cleanly – its only byproducts are carbon dioxide and water.  But any source of heat should work as long as you can use it to boil the sap.

Note: See my list of 5 Reasons to Use a Turkey Fryer for Making Maple Syrup.

Step 2: Fill the Pot With 5 Gallons of Sap

Pour 5 gallons of sap into your boiling pot and start the boiler.

I often like to start boiling with 2-3 gallons of sap, and once the boiling has started, add a gallon about every hour or so in order to get the boiling to start faster.

Maple Syrup Boiling in a Propane Stove or Turkey Fryer
Propane Boiler for Boiling Maple Syrup

In order to increase the surface area of the sap being boiled and therefore increase the rate of evaporation, I’ve also used a cooking pan.

boiling maple syrup outside on a propane burner

Step 3: Boil the Sap for 4 hrs.

Set it at a medium heat and wait for it to start boiling. Once the sap starts to boil, you may need to adjust the heat slightly so that it keeps a nice rolling boil.

If it is too hot, it will start to boil over. If it is too low, you won’t see bubbles coming up.

Not sure how long you will need to boil your sap? Use the Jones Rule of 86 to find out!

Use a stir paddle to stir the sap occasionally. Once a rolling boil has started, adjust the heat so that it remains rolling without a lot of bubbles and without foam completely covering the top surface.

The goal here is to dissipate steam, if there are a lot of bubbles on top, they can actually have an insulating effect and increase the amount of time it takes to boil off most of the water.

Watch the steam coming off the top and when you have this maximized, that is the temperature you want to remain at.

In the picture below, the sap has been boiling for about 1 hour.

maple syrup boiling using propane is simple

Every now and then skim the foam off of the top using a skimming spoon.

Getting rid of the foam will help cut down on the cloudiness of the final product and allow for more and faster evaporation of the excess water.

Maple syrup skimming spoon foam

Continue to boil down the sap until you have about 1.5″ to 2″ of sap in the bottom of your kettle.

This will take about 4-5 hours. This will get your sap to about the 10:1 ratio.

maple syrup boiling nearing 10 to 1 ratio

Step 4: Finish the Boiling on a Stove

In the following picture, the sap is nearly done boiling outside, notice the rich dark color of the sap, which is due to the Maillard Reaction.

Soon, we will turn off the burning and bring the sap inside for the final boiling.

Maple Syrup almost done boiling!

Finish boiling the sap to the final sugar content on an indoor stove – for more control.

Step 5: The Syrup is done when it reaches 219° or 66% sugar content

I recommend doing the ‘finishing boil‘ on a stove so that you can keep a closer eye on it as well as to monitor the temperature more closely.

It is not exactly obvious when the syrup is 'done.' Technically it is done when it has reached 66% sugar content.

You can measure this exactly with a kitchen refractometer – an inexpensive device that looks like a kaleidoscope that measures the sugar content of syrup by dripping a few drops onto its viewing slide.

A refractometer reading the sugar content of Maple Syrup
A refractometer reading the sugar content of Maple Syrup

A complete description of the finishing boil and a picture guide on using a refractometer is given in the next article on How to Perfect the Finishing Boil for Maple Syrup.

Interested in using a Refractometer? Check out my post: How to Use a Refractometer for Perfect Maple Syrup!
For more FREE information on making Maple Syrup, visit the Maple Syrup Hub!

Tools and Supplies Mentioned in this Post:

People Also Ask…

Some additional common questions related to making Maple Syrup:

How Long Does it Take to Boil Maple Syrup?

I find that it takes about 4 hours to boil down 5 gallons of Maple sap into syrup. This time may vary depending on the sugar concentration of your sap and your evaporator (method of heating the sap).

What do you Use to Make Maple Syrup?

In general, you need spiles and collection vessels to collect Maple sap from the tree, and a way to boil the sap down into syrup. Check out my Maple Syrup Resources page for the specific equipment used for making Maple Syrup at home.

How do I know when Maple Syrup is done boiling?

Maple Syrup is done boiling once it has heated up to 219 degrees Fahrenheit, or 66% sugar content. Water boils at 212 deg F. As the water boils off and the syrup becomes more concentrated, the boiling point increases gradually. Once the temperature of the syrup has reached 219 deg F (or, more precisely 7.1 deg above the boiling point of water at your altitude), your Maple Syrup is done!

To see this in action, check out this video: How to Know When Maple Syrup is Done Boiling on YouTube.

Can you stop boiling sap for the night?

Yes, you can! I frequently do this. If the sap is not done boiling, you can take it off the heat for the night. The sap/syrup should be kept cool (around 35 deg F or colder), such as in a refrigerator or outdoors if the temperature is cool enough. It is also recommended to cover the pot or boiling vessel so that insects and other detritus does not fall into the sap.

One thing to be aware of is that if you stop for the night (or any length of time) the final syrup will become darker than it would have been if you had boiled straight through, due to the extended time over which the Maillard Reaction takes place.

Why does my homemade Maple Syrup Crystalize?

Crystalized maple syrup typically occurs when the sap is boiled too long, and the sugar content has increased beyond 68.9% sugar content. Pure Maple Syrup should have a sugar content between 66-68.9%. You can measure the exact sugar content of your syrup while boiling by using a maple syrup refractometer.

A common cause for crystalized maple syrup is the use of an inaccurate thermometer. Pure Maple Syrup boils at 219.1 deg F (most people just use 219 deg F). To check your thermometer, boil some water and verify that the temperature of boiling water is 212 deg F, or the expected temperature at your altitude (barometric pressure/temperature).

crystalized maple syrup
Crystalized Maple Syrup

Can you over boil Maple Syrup?

Yes, you can over boil Mape Syrup. You should boil it to 219 deg F and then stop. Pure Maple Syrup should have a sugar content between 66-68.9%. You can measure the exact sugar content of your syrup while boiling by using a maple syrup refractometer. Once your syrup reaches 66% sugar content, remove it from the heat.

What temperature does Maple Sap boil at?

Initially, Maple sap will boil at a temperature very close to that of water (212 deg F at standard temperature/pressure). However, as water boils away in the form of steam, the sugar in the sap is concentrated and the temperature at which the solution boils will increase. Maple sap officially becomes Maple Syrup once the boiling point has reached 219.1 deg F, or 7.1 deg F above the boiling point of water.

For answers to even more common questions about harvesting and boiling maple sap, check out our popular Frequently Asked Questions!

Maple Syrup Resources

There are a lot of resources available online for wisdom on making your own Maple Syrup. I’ve compiled a number of links to free eBooks, guides, templates, and equipment, and put them together on my Maple Syrup Resources page.

Additional Articles in this Series on Maple Syrup Making!

These are the links to the other articles in this series:

See these Steps on YouTube!

How to Make Maple Syrup on YouTube - Practical Mechanic
Watch “How to Make Maple Syrup in 4 Minutes” on YouTube!

Play the “How to Make Maple Syrup Podcast!”

Check out my podcast on How to Make Maple Syrup!

Identifying Maple Trees, Sugar Content, and Taste (Rebroadcast) How to Make Maple Syrup!

In this episode, we'll discuss: 1. How to identify maple trees and some specifics of the different varieties. 2. The sugar content of different Maple Trees. 3. How sugar content varies over the season and from year to year. 3. We'll then talk to Rachel and get her take on the taste of Maple Syrup from different Maple Trees. Download the FREE – How to Make Maple Syrup Cheat Sheet found here: https://practicalmechanic.com/maplesyrup Welcome to the "How to Make Maple Syrup Podcast"! My name is Richard Tomlinsen, and in this series, I am going to walk through, in detail, the super easy steps to follow to make your own delicious Maple Syrup! My Goal is that by the end of listening to this series, you will have all of the information you need to get started tapping your maple trees, collecting the sap, boiling it, and finally performing the finishing boil in order to bottle that perfect golden elixir! In this 5-part series we are going to cover the following topics: 1. How to Identify and When to Collect Sap (What kinds of Maples can produce Syrup? How many do you need?) 2. How to Tap Maple Trees for Maple Syrup (Including best practices for keeping your trees healthy!) 3. How to Boil Sap for Maple Syrup (Easiest methods and how long it will take!) 4. How to Perfect the Finishing Boil (Take the guesswork out of "When is my syrup done?") 5. How to Bottle Maple Syrup (Tips for bottling Maple Syrup for your Family and Friends!) I hope you have as much fun listening as we are having making these episodes! Why am I doing this? I love making maple syrup! It has been a tradition in my family ever since I was very young, and it brings so much joy to our family! I hope to bring that joy to you as well! I hope that after you have listened to this podcast series, you will be equipped with how to start a fun, inexpensive hobby that you can do with your family and friends to draw closer to each other! — Send in a voice message: https://anchor.fm/how-to-make-maple-syrup/message
  1. Identifying Maple Trees, Sugar Content, and Taste (Rebroadcast)
  2. Introducing the "How to Make Maple Syrup" Podcast! (Rebroadcast)
  3. Top 5 Lesser-Known Mistakes When Making Maple Syrup
  4. What are the Top 5 Most Common Mistakes When Making Maple Syrup?

The “How to Make Maple Syrup Podcast!” is enjoyed by hundreds of listeners each week during the maple-sugaring season. We’d love for you to join us! We discuss our favorite tips and tricks for making maple syrup as well as interesting information related to the golden elixir!

Click the links below to listen and subscribe in your favorite podcast player!

Or listen right from your browser:

How to Make Maple Syrup Podcast!

Maple Syrup Merch!

Check out these Got Maple and Sugar Maple Leaf T-Shirts, as well as the Fall Maple Leaf T-Shirt!