What Size Gutter Sealant Do You Need for Your Gutters?

Size depends on joints, not width

Gutter width has little to do with how much sealant you need. A 5-inch gutter and a 6-inch gutter leak in the same places: seams where sections join, inside and outside corners, end caps and downspout outlets. Each of those joints needs its own bead of sealant, so the number of joints drives the size you buy.

That is why this question is really about the job. One weeping seam is a small repair. A whole roofline with cracked old sealant at every joint is a much bigger one. Pick the size that matches the work first, then choose the formula that suits your weather and gutter color.

Sealant sizes at a glance

Here is how the products on our gutter sealant comparison line up by size. All volumes come from the published specifications, and none of these products is sold by the gallon.

Count your joints before you buy

Walk the roofline from the ground with a notepad. Do not climb up just to count. Look for these spots and tally each one:

• Straight seams where two gutter sections overlap or join.
• Inside and outside corners, where sections meet at an angle.
• End caps at both ends of every run.
• Downspout outlets, where the drop connects to the gutter.
• Any place where old sealant has cracked, shrunk or pulled away.

Match the tube to the job

The smallest tube on our page holds 4.5 fl oz. The DAP Dynaflex is that size, meets ASTM C719 for joint movement and is listed as water ready in 30 minutes. It fits a single leaking seam or a loose end cap, and you will not be left with a lot of leftover sealant.

In the middle are tubes of 9 to 10.3 fl oz. The DAP Advanced Gutter & Flashing Sealant holds 9 fl oz, the DAP Gutter & Flashing Advanced Sealant holds 10.1 fl oz, and the single Geocel 2320 tube holds 10.3 fl oz. These suit a handful of seams, a corner or two and a few outlets.

For a whole house, or for repairs done in stages, the Geocel 2320 three-pack holds three 10.3 fl oz tubes, 30.9 fl oz in total, the most on our page. Our best gutter sealant picks show how each size pairs with its formula, cure time and color.

What else changes how much you use

Tube size is only part of the story. A few details can make a tube go further or run out sooner.

If you are close to the line between two sizes, the larger tube is usually the safer choice, as long as you can store it well.

• Bead size: a thin, neat bead in a narrow seam uses far less than a thick, messy one.
• Old sealant: joints that need the old material removed and redone take more work and more product.
• Weather: some sealants need a dry, mild day, while the DAP Advanced Gutter & Flashing Sealant lists application from 0°F and on wet surfaces.
• Color: sealant shows on the outside of the gutter, so choose clear, white or gray to match before you open a tube.

Prep and safety before you start

Scrape off loose old sealant, dirt and leaves first. Sealant does not bond well to grime, so a clean seam matters as much as the amount you apply. Unless your product is made for wet surfaces, wipe the seam dry.

Ladders are the main hazard on this job. Set the ladder on firm, level ground, keep three points of contact and never reach far to the side. Stay well clear of power lines and the service drop near the roofline.

Wear safety glasses, because old sealant and debris can fall into your eyes as you scrape, and wear gloves. Read the label for ventilation advice, cure time and temperature limits before you begin.

Frequently asked questions

What size gutter sealant tube should I buy?

Choose by the number of joints. A 4.5 fl oz tube suits one or two spot repairs, a 9 to 10.3 fl oz tube covers several seams and corners, and a 30.9 fl oz three-pack fits a whole-house reseal or repairs done over several weekends.

Does gutter sealant come in a gallon size?

None of the products on our sheet come in a gallon. Packs here run from 4.5 fl oz to 30.9 fl oz total. Sealant for gutter seams is sold mainly in caulk-style tubes, which are easier to apply to narrow joints.

Do 5-inch and 6-inch gutters need different sealant sizes?

Gutter width has little effect on which tube you need. What counts is how many seams, corners, end caps and outlets need sealing. A longer run with more joints uses more sealant than a short run, whatever its width.

Can I save a partly used tube for later?

Often you can, if you seal the nozzle tightly and store the tube as the label directs. Sealant can skin over or harden in the nozzle, so a smaller tube sized to your job is often the simpler way to avoid waste.