How deep can I pour epoxy for a river table in one layer?

Standard resins: max ½″–¾″ per pour to avoid dangerous exothermic heat. Deep-pour casting resins (designed for thick pours) can handle 1″–4″ per layer. Always check your product's maximum recommended depth.

What is void fill percentage and what should I use?

Void fill accounts for the fact that wood edges extend into the river channel — the void is never 100% open. Use 80–85% for rustic edges, 85–90% for clean-cut slabs. Our calculator defaults to 85%.

How Much Epoxy Do I Need for a River Table?

Q: How do I calculate how much epoxy I need for a river table?

Measure only the void (river channel): length × width × pour depth. Multiply by your void fill percentage (80–90% is typical to account for wood intrusion). Add a 10–15% waste buffer. Use fl oz = cubic inches ÷ 1.805.

Q: How many ounces of epoxy do I need for a 6-foot river table?

A 72″ × 8″ × 1.5″ river channel at 85% void fill = 72×8×1.5×0.85 = 734 cu in ÷ 1.805 = ~407 fl oz net. Add 10% waste buffer = ~448 fl oz total (about 3.5 gallons).

Q: Why do I measure the river channel and not the whole table?

The solid wood slabs sit beside the river channel — they don't need epoxy. Only the void (the gap between the slabs) gets filled. Measuring the whole table would massively overestimate the epoxy needed.

The key mistake most beginners make is measuring the entire table instead of just the void. For a river table, you only fill the river channel — the gap between the two wood slabs. This guide walks you through the exact calculation method, void fill percentage, and pour layer planning so you buy the right amount the first time. You can also skip straight to the River Table section of our free epoxy calculator for instant results.

Enter your river channel dimensions below and get exact epoxy volume, mix breakdown, and cost estimate — instantly.

🪵 Open River Table Calculator ⟶

📐 The Calculation Formula

Step-by-Step: How to Calculate Epoxy for a River Table

Follow these four steps to get your epoxy volume:

Measure the river channel — length, width, and pour depth in inches. Do not measure the wood slabs.
Calculate gross cubic volume — Length × Width × Depth = cubic inches.
Apply void fill % — Multiply by 0.80–0.90 to account for wood edges extending into the channel.
Convert to fluid ounces — Divide cubic inches by 1.805. Then add your waste buffer (10–15%).

Epoxy (fl oz) = (L × W × D × void%) ÷ 1.805 × (1 + waste%)

Example: A 72″ long × 8″ wide × 1.5″ deep river channel at 85% void fill:
72 × 8 × 1.5 × 0.85 = 734.4 cu in ÷ 1.805 = 407 fl oz net. Add 10% buffer = 448 fl oz total (~3.5 gallons).

🪵 Void Fill % Explained

What Is Void Fill Percentage and What Should You Use?

The void between your wood slabs is never 100% empty. Wood edges, knots, and natural irregularities extend into the channel. Void fill % accounts for how much of that measured volume is actually open space.

Wood Edge Style	Recommended Void Fill %
Live edge, rough and organic	75–82%
Typical live edge (most tables)	82–88%
Clean-cut, straight edges	88–95%
Straight bookmatched slabs	90–95%

When in doubt, use 85% — it's the safe middle ground for most live-edge river tables. Our calculator defaults to this value.

🌊 Pour Layers

How Many Pours Do You Need?

Standard epoxy resins release heat as they cure (exothermic reaction). Thick pours trap this heat, which can cause cracking, yellowing, or even dangerous smoke. Plan your pours based on your resin type:

Resin Type	Max Per-Layer Depth	Typical Use
Standard tabletop / coating resin	¼″ – ½″ (6–12 mm)	Thin river channels, sealing
Deep-pour casting resin	1″ – 4″ (25–100 mm)	Deep river channels, casting
Slow-cure river table resin	¾″ – 2″ (20–50 mm)	Most river table projects

For a 1.5″ deep channel using standard resin, plan for 3 pours at ½″ each. Wait for each layer to reach a firm gel (not fully cured) before pouring the next — typically 4–8 hours between pours.

The total epoxy volume does not change with more pours — you're just spreading the same amount across multiple layers. Enter the number of pours in our calculator to see the per-layer breakdown.

📊 Quick Reference Table

Common River Table Epoxy Estimates

These estimates use 85% void fill, 1.5″ pour depth, and 10% waste buffer:

Table Size	River Width	Net Epoxy	With 10% Buffer
4 ft (48″)	6″	201 fl oz	221 fl oz (~1.7 gal)
5 ft (60″)	7″	294 fl oz	324 fl oz (~2.5 gal)
6 ft (72″)	8″	407 fl oz	448 fl oz (~3.5 gal)
7 ft (84″)	9″	533 fl oz	587 fl oz (~4.6 gal)
8 ft (96″)	10″	678 fl oz	746 fl oz (~5.8 gal)

Your river channel dimensions will differ — always calculate with your actual measurements using the epoxy calculator for accuracy.

Frequently Asked Questions

How do I calculate how much epoxy I need for a river table?

Measure only the void (river channel): length × width × pour depth in inches. Multiply by your void fill % (0.80–0.90). Divide by 1.805 to get fluid ounces. Add a 10–15% waste buffer. Use the river table calculator to do this instantly.

How many ounces of epoxy do I need for a 6-foot river table?

A typical 72″ × 8″ × 1.5″ channel at 85% void fill requires about 407 fl oz net (448 fl oz with 10% buffer — roughly 3.5 gallons). Narrower or shallower channels need less; wider or deeper need more. Always use your actual measurements.

Why do I measure the river channel and not the whole table?

The solid wood slabs don't need epoxy — only the gap between them (the river channel) gets filled. Measuring the full table top would give you 5–10× more epoxy than you actually need, wasting hundreds of dollars.

How deep can I pour epoxy in one layer for a river table?

Standard resins: maximum ½″ per pour. Deep-pour casting resins (TotalBoat ThickSet, Entropy CCR, etc.): up to 2″–4″ per pour. Exceeding these limits causes dangerous exothermic heat that cracks or yellows the epoxy. Always check your product's datasheet.

What void fill percentage should I use?

Use 80–85% for rough, organic live edges with lots of natural character. Use 85–90% for typical live-edge slabs. Use 90–95% for clean, straight-cut edges. When in doubt, default to 85% — it's the safest choice for most projects.