Easy Epoxy Calc

How much epoxy for a river coffee table?

Short answer

You need about 2.14 gallons of mixed deep-pour epoxy for a 4 ft (48-inch) river coffee table with a river averaging 6 inches wide on 1.5-inch slabs — 1.95 gallons fills the channel, poured 1/16 inch proud for flattening, and the rest is a 10% waste allowance.

How to work it out

  1. 48 in × 6 in × (1-1/2 in + 1/16 in proud) = 450 cu in = 1.95 gal
  2. + 10% waste = 2.14 gal → 1 × 3 gal kit
  3. Lifts: 1-9/16 in ÷ 2 in per layer → 1 lift
  4. Batches: 2.14 gal ÷ 1.5 gal max → 2 → A 2.86 qt (6.86 lb) + B 1.43 qt (2.89 lb) each
  5. Mix ratio 2 : 1 by volume, SG A 1.15 / B 0.97 (typical, not published by the maker — type your data sheet’s SGs for exact weights) → Part A 1.43 gal (13.7 lb) + Part B 0.71 gal (5.78 lb)

Coffee tables are the usual first river table: short slabs, a narrow river, and a pour you can mix in two buckets. The 1.95 gallons of channel includes the 1/16 in you pour proud of the wood; the allowance on top covers the film left in the mixing buckets, the seal coat brushed on the live edges, and a small leak or two through the form.

Adjust for your project

in
in
Measure across the gap, not the whole table — the diagram just below the calculator shows where.
in
Your slab thickness at the thickest spot. About 1/16 in extra, so you can sand it flat, is added for you (“Pour proud” under More options). Many deep-pour resins also have a minimum depth — often 2 in.
in
On the label as “max pour depth”. Not bought yet? Leave 2 in — many deep-pour epoxies allow 1–2 in per layer.
Total of both bottles together. Most “1 gallon kits” are ½ gal resin + ½ gal hardener — enter 1. If the listing says 1 gal of EACH, enter 2.
More options: waste · proud · product …
%
Cup and bucket film, small leaks, the seal coat on the live edges. Use 15% for very open or punky wood.
in
Resin poured above the wood so the whole top can be sanded flat — 1/16 in is typical. Enter 0 if you already added it to the depth.
Fills in the mix ratio, weights and depth limits from the maker’s published data, and hides those fields. Always check the data sheet that comes with your batch.
in
From the label — e.g. MAS Deep Pour X 2 in, FlowCast 1/2 in
gal
Some labels lower the deepest layer for big pours, or cap the volume per layer. Enter that volume here; leave blank if your label doesn’t.
fl oz
Open knots and cracks that join the river fill up too. A rough guess is fine: a 1 × 1 × 3 in knot holds about 1.7 fl oz.
Only changes the Part A / Part B split — it’s printed on the kit. Tabletop and art resins are usually 1:1; deep pour often 2:1.
From the TDS, in g/ml. Leave blank for 1.15 (typical, not published by the maker).
From the TDS, in g/ml. Leave blank for 0.95 on 1:1 kits or 0.97 on other ratios (typical, not published by the maker).
gal
Resin + hardener mixed in one bucket. Leave blank to mix one whole kit at a time; enter less (1.5 gal or 6 L is easy with a drill paddle) to split each lift into batches you pour back to back.
From the label: when the next layer can go on (the recoat window) at room temperature. Leave blank to skip the pour schedule.
From the label: how long after the last pour before the table can come out of the form.
$
Optional — your kit price, for a cost estimate
Deep-pour epoxy to buy2.14 gal8.57 qt · 8.11 L
In short
Buy 1 × 3 gal deep-pour kit. Pour the river in one layer, mixed in two batches.
What the resin will weigh in the table (for the form and legs)
17.9 lb (8.11 kg)
Left over from the last kit
0.86 gal (3.43 qt · 3.24 L)
Mixing details: batches, Part A and Part B
Mixing details: batches, Part A and Part B
Part A (resin)Part B (hardener)
Each batch (2 in all)2.86 qt · 6.86 lb1.43 qt · 2.89 lb
Whole job1.43 gal · 13.7 lb0.71 gal · 5.78 lb
  • What to buy: 1 × 3 gal deep-pour epoxy kit. Each kit has both bottles (resin + hardener) — you don’t buy them separately.
  • Check the label’s minimum depth too. Many deep-pour resins list a minimum pour as well as a maximum — MAS Deep Pour X, for one, wants at least 2 in, and thinner pours cure slowly or stay soft. At 1-9/16 in, choose a resin whose range includes that depth, and type its minimum under Min depth per pour (More options) to check.
  • Mix 2 batches of about 1.07 gal and pour them back to back into the same layer, before they start to thicken. Some labels also cap the mass per pour — check yours.
  • Seal the live edges and any bark with a thin coat first — dry wood soaks up epoxy and releases bubbles into the pour.
  • About 0.86 gal will be left in the jugs. Kept sealed, it fills knots and cracks later, or makes a practice river board.

For this job · affiliate link
Deep pour epoxy kitYou need 2.14 gal — 1 × 3 gal kit. Pick one whose label range includes 1-9/16 in per pour — the minimum as well as the maximum; a tabletop resin would overheat at 1-1/2 in deep.
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Coffee table epoxy by average river width (48 in long, 1.5 in slabs)

Coffee table epoxy by average river width (48 in long, 1.5 in slabs)
Average river widthDeep-pour epoxy to buyKits to buyWhat the resin will weigh in the table (for the form and legs)
4 in1.43 gal1 kit11.9 lb
5 in1.79 gal1 kit14.9 lb
6 in2.14 gal1 kit17.9 lb
7 in2.5 gal1 kit20.9 lb
8 in2.86 gal1 kit23.8 lb

What to know about a river coffee table

Most coffee tables are 40–48 in long, 20–24 in wide and 16–18 in tall, so the two slabs are often halves of one short plank, flipped so the live edges face each other (bookmatched). That keeps the grain running across the river and gives both edges the same thickness — which matters, because the depth you enter should be the thickest point of either slab.

Kit fit is awkward at 2.14 gallons. A single 1.5-gallon kit is too small, so you are buying 3 gallons either way: one 3-gallon kit or two 1.5-gallon kits (MAS Deep Pour X, for example, is sold in 1.5, 3 and 6 gallon sizes). Both leave about 0.86 gallons unmixed in the jugs. Kept sealed, that is plenty for a practice board — see How much epoxy for a river charcuterie board.

Thin pours are the catch at this size. A 1.5 in river is shallow for some deep-pour resins. MAS lists a 2 in minimum casting depth for Deep Pour X and says pours under 2 in can take 48–72 hours to cure: a thinner layer builds up less heat, so the reaction runs slower. Pick MAS Deep Pour X under Epoxy product and the calculator flags exactly that. Choose a product whose label range includes about 1 9/16 in, keep the room warm and steady, and don’t unclamp or flip the top until it is hard all the way through.

Two buckets, not one. Mixed at most 1.5 gallons at a time (this example’s Largest batch), the pour splits into two batches of about 1.07 gallons, mixed one after the other. The finished river holds about 17.9 lb of resin — light enough that a simple melamine form on a flat bench is plenty.

Building something desk-length instead? How much epoxy for a 5 ft river table runs the same arithmetic for 60 in.

Different size? Use the full River Table Epoxy Calculator.

What you’ll need

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Frequently asked questions

How much epoxy for a river coffee table 2 inches thick?

About 2.83 gallons with 10% waste — still 1 kit of 3 gal, but only 0.17 gal to spare, which is a tight fit for a first pour. With a 2 in resin it is also 2 pours, because of the 1/16 in poured proud.

How much epoxy for a coffee table with a 4 inch river?

About 1.43 gallons of mixed epoxy (1.3 gal of channel plus 10%), still 48 in long on 1.5 in slabs.

How many 1.5 gallon kits for a river coffee table?

2 kits. You need 2.14 gal with waste, more than one 1.5 gal kit holds, so two leave 0.86 gal spare.

Other common sizes

Sources